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C H A P T E R 26Principles of SurgicalTreatment

The primary goal of strabismus surgery is toeliminate the relative deviation of the visual

axes. Surgery is performed for functional reasons,to create comfortable single binocular vision, or,if this cannot be accomplished, to reestablish anormal facial configuration by aligning the eyes.The term ‘‘cosmetic surgery’’ in connection withoperations for strabismus in adults should beavoided since this description is not only incorrectbut may also be unacceptable to some insurancecarriers and managed care providers. Cosmetic sur-gery is defined as surgery performed to improvethe appearance of a normal person. Since strabis-mus is an abnormal sensory and motor state of theeyes, its surgical correction falls under the categoryof reconstructive surgery, the goal of which is toeliminate a disease, abnormality, or defect.4, 105, 262

The term cosmetic surgery is a also a misnomer inview of the fact that in many instances functionalvisual benefits may be expected from correctingstrabismus in adults.142, 146, 226, 244, 254, 303

Whatever the indication, the effect of an opera-tion is mechanical, since the position of the globein the orbit is changed, thus altering the effective-ness of extraocular muscle contraction. Surgicalprocedures cannot directly affect the innervationreaching the eyes. This can happen only indirectlywhen innervational and sensory factors adjust tothe newly created anatomical and mechanical con-ditions that have created a new stimulus situation.

The purpose of surgery should be to correct thestatic angle of strabismus. Operations to change

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the dynamic angle as defined by us (see p. 180)invariably lead to undesirable results. In paralyticstrabismus only those patients in whom the devia-tion interferes with comfortable single binocularvision in the practical field of fixation (see Chapter4) should be considered for surgical treatment.

History and GeneralComments

The earliest reference to strabismus surgery canbe found in the early eighteenth century in thewritings of an itinerant English oculist namedJohn Taylor. ‘‘Chevalier’’ Taylor, as he called him-self, traveled through continental Europe to lectureand perform eye surgery.14 He left a trail of deteri-orating sight and blindness behind him and hasbeen called the greatest charlatan of all oculistswho ever lived. His self-glorification and shame-less publicity stunts would have made even themost aggressive advertising of contemporary ‘‘la-ser surgeons’’ appear to be exercises in modesty.According to an eyewitness, Le Cat, who laterwrote a book about Taylor, strabismus surgeryconsisted of excising a piece of conjunctiva fromthe lower fornix.113, p. 166 Taylor claimed that byexcising some of its nerve supply an overactingmuscle was weakened. After surgery the eye notoperated on was bandaged and great was the aweand admiration of the spectators when the eyeoperated on straightened out and remained straight

Principles of Surgical Treatment 567

. . . until several days later when the bandage wasremoved and the squint returned. But by that timeTaylor had moved on to the next town and notbefore collecting a sizable surgical fee. Le Cat,who knew about the nerve supply to the extraocu-lar muscles, expressed his doubts about the effec-tiveness of this operation in an unusually dramaticand macabre fashion. Once after an excellentlunch he had a covered dessert dish served toTaylor. When the cover was removed it revealed ahuman head in which the nerves to the extraocularmuscles had been carefully dissected.113, p. 167 Itwas obvious that none of the nerves could havebeen reached with Taylor’s technique and the em-barrassed surgeon left town, his local reputationshattered. Despite his unscrupulousness Taylor de-serves credit for being the first to mention inhis writings that myotomy of a muscle may curestrabismus. However, none of his contemporarieswitnessed that Taylor had actually performed thisoperation himself.

It was not until a century later, on October 26,1839, at 3 PM to be exact,114, p. 322 that JohannFriedrich Dieffenbach, a general surgeon fromBerlin and professor at the famous Charite, cor-rected strabismus by performing a myotomy of amedial rectus muscle in a 7-year-old esotropicchild. Dieffenbach was a popular and famous sur-geon in his day to whom medicine owes numerousinnovations. Many consider him the father of or-thopedic and plastic surgery. When he walkedthrough the streets of Berlin the street urchinsgreeted him with this ditty:

Wer kennt nicht Doktor Dieffenbach,den Doktor der Doktoren?Er schneidet Arm und Beine ab,macht neue Nas’ und Ohren*

It is highly probable that the rationale for thisoperation evolved from successfully treating club-foot with weakening of the Achilles tendon ortorticollis with a myotomy of the sternocleidomas-toid muscle. Dieffenbach had a considerable per-sonal experience with both operations.235 Dieffen-bach published this case only a few days later, onNovember 13, 1839,56 and mentioned in his reportthat Louis Stromeyer, another German surgeon,had performed this operation on a cadaver.

It so happened that a Belgian ophthalmologist,Florent Cunier, who had also become aware ofStromeyer’s report, performed a myotomy of the

*Who does not know Dr. Dieffenbach,/The doctors’ doctor?/He cuts off arms and legs,/Makes new noses and ears.

lateral rectus muscle in a patient with exotropiaonly 3 days after Dieffenbach’s feat.114, p. 335 Actu-ally, Cunier’s report of his operation in the An-nales d’ Oculistique preceded Dieffenbach’s publi-cation in the Medizinische Zeitung by 2 weeks.Not surprisingly, an ardent and ugly disputeevolved when Cunier challenged Dieffenbach’spriority. This disagreeable situation was furtheraggravated when the prestigious and substantial(6000 gold francs!) Montyon Prize of the RoyalAcademy of Science (Paris) was shared by Stro-meyer for first suggesting the operation and per-forming it in cadavers and by Dieffenbach forbeing the first to perform it successfully in apatient.114, p. 335

Dieffenbach’s publication in 1839 secured himpriority as the father of strabismus surgery, but hemay not have been the first to treat esotropia witha myotomy of the medial rectus muscle. In fact,it is quite likely that he was preceded by WilliamGibson of Baltimore, a noted general surgeon andprofessor at the University of Maryland. In thesixth edition of his textbook, The Institutes andPractice of Surgery (1841),83 Gibson reported thathe had performed this operation in four patientsin 1818, that is, 21 years before Dieffenbach.However, because the results were disappointing(three undercorrections, one overcorrection), Gib-son abandoned this procedure. He graciouslystated that he did not intend to question Dieffen-bach’s glory as the originator of the myotomy butregretted not having persisted and operated on alarger number of patients.

The news of a surgical cure of strabismusspread through Europe and America with tele-graphic speed. Only 2 years after his first publica-tion Dieffenbach had done 1200 cases.114, p. 324

Ether anesthesia was not discovered until 1846and several helpers were needed during the opera-tion, one surgeon and two or three assistantswhose task it was to immobilize the sitting patientand to pry the lids open. In 1839 only eightsuch operations had been performed at the RoyalWestminster Eye Hospital, but in 1840 over 400procedures were done, more than 365 of them inless than 7 months by a single surgeon.222 TheFrench ophthalmologist Fleussu wrote that ‘‘neverhas an operation been accepted with similar enthu-siasm as the operation for strabismus. Surgeonssnatched patients from each other or chased themlike game whose meat would be suited to feedand fatten one’s own reputation.’’73, 235

The operation was performed in the United

568 Principles of Therapy

States soon after it became popular in Europe andEngland. A treatise on strabismus surgery waspublished in 1842 by James Bolton of Virginia22

with illustrations of instruments that look not allthat much different form those we are using today.

We became aware of one of the first and per-haps most colorful descriptions of muscle surgeryin those days in Stephens’s fascinating diary ofhis 1841 expedition to Yucatan.278 Stephens wasaccompanied on this trip by a Dr. Cabot of Bostonwho performed this procedure on a 14-year-oldboy, and Stephens outlined the operation as fol-lows: ‘‘The cure discovered is the cutting of thecontracted muscle, by means of which the eyefalls immediately into its proper place. This mus-cle lies under the surface; and, as it is necessaryto pass through a membrane of the eye, the cuttingcannot be done with a broadaxe or a handsaw.’’Stephens then went on to describe the operationperformed by Dr. Cabot in a ‘‘stout lad of about19 or 20’’:

As soon as the doctor began to cut the muscle, however,our strapping patient gave signs of restlessness; and allat once, with an actual bellow, he jerked his head onone side, carried away the doctor’s hook, and shut hiseye upon it with a sort of lockjaw grip, as if determinedit should never be drawn out. How my hook got out Ihave no idea; fortunately, the doctor let his go, or thelad’s eye would have been scratched out. As it was,there he sat with the bandage slipped above one eye,and the other closed upon the hook, the handle of whichstood out straight. Probably at that moment he wouldhave been willing to sacrifice pride of personal appear-ance, keep his squint, and go through life with his eyeshut, the hook in it, and the handle sticking out; but theinstrument was too valuable to be lost. And it wasinteresting and instructive to notice the difference be-tween the equanimity of one who had a hook in his eye,and that of lookers-on who had not. All the spectatorsupbraided him with his cowardice and want of heart,and after a round of reproof to which he could makeno answer, he opened his eye and let out the hook. Buthe had made a bad business of it. A few seconds longer,and the operation would have been completed. As itwas, the whole work had to be repeated. As the musclewas again lifted under the knife, I thought I saw a glarein the eyeball that gave token of another fling of thehead, but the lad was fairly browbeaten into quiet; and,to the great satisfaction of all, with a double share ofblackness and blood, and with very little sympathy fromanyone, but with his eye straight, he descended fromthe table. Outside he was received with a loud shout bythe boys, and we never heard of him again.

But, as one may have expected, the initial ex-citement with this operation soon wore off. Inmany cases the outcome was a huge overcorrec-tion which Dieffenbach treated by myotomizing

the lateral rectus and passing a suture through itstendon, which was then fastened to the oppositeside of the nose. This traction suture was called‘‘Fadenoperation’’ and it is unfortunate that thisterm was usurped in our time to describe a com-pletely different procedure, the retroequatorial my-opexy. Although there were patients with goodresults, presumably from spontaneous scleral reat-tachment of the distal muscle segment further pos-teriorly, Laqueur149 observed in 1908 that ‘‘afterthe initial reports of 1842 the publications aboutstrabismus decreased progressively and concernedmostly efforts to reverse the effect of surgery,’’and Javal129 spoke of the ‘‘slaughter’’ of extraocu-lar muscles that had taken place.

The early phase of strabismus surgery hadended and even though Critchett reported ad-vancement of a rectus muscle in 1855, it was notuntil 1857 when a new era of strabismus surgerybegan with publication of Albrecht von Graefe’sclassic monographs on strabismus surgery.92, 93 VonGraefe, who is considered by most as one of thefathers of modern ophthalmology (the other threebeing Helmholtz, Donders, and Bowman) definedthe indications for tenotomy, improved the tech-nique, and added controlled recession and resec-tion and advancement of a muscle to the surgicalarmamentarium. His younger nephew and disci-ple, Alfred K. Graefe, is rarely mentioned in thisconnection but made similarly important contribu-tions to the surgical treatment of paralytic strabis-mus.91, 295

In our time, free tenotomies (or myectomies)of the rectus muscles have been replaced by reces-sions and have but sunk into oblivion. An excep-tion is tenotomy of the inferior rectus muscle,which is used in rare cases of severe endocrineophthalmopathy or congenital fibrosis. In bothconditions the tightness of the muscle may be sopronounced that it is technically impossible topass sutures through its tendon at the insertion.Tenotomies of the superior oblique muscle andmyectomies of the inferior oblique muscles arebeing performed to this day.

Choice of Operation

When the need for surgery has been established,the muscle or muscles to be operated on must bedetermined. Only two procedures can affect theaction of an extraocular muscle and thereby alterthe position of the eyes. The action of a muscle


can be weakened or the action of the antagonistmuscle strengthened; the two procedures can alsobe combined. We emphasize that we are speakingof weakening or strengthening the action of amuscle rather than of the muscle itself since mostof the currently used surgical procedures do onlyjust that.

Motility Analysis

VERSIONS. An important criterion for choosingthe appropriate surgical procedure is based on thestudy of versions. In most patients with comitantheterotropia, abnormalities of rotations are pres-ent. In esotropes, for instance, adduction may beexcessive and abduction deficient. In exotropes,abduction may be excessive and adduction defi-cient, or both conditions may coexist. Surgicalprocedures on extraocular muscles should normal-ize the excursions of the eyes and if successfulshould reduce the deviation automatically.

For example, if movement of the globe is ex-cessive in a particular direction, the action ofthat muscle should be weakened. If movement isdeficient, strengthening the action of the appro-priate muscle is indicated. Thus in a patient withesotropia, excessive adduction, and normal abduc-tion, we perform a maximal recession of the me-dial rectus muscle and only a nominal resectionof its antagonist. On the other hand, if deficientabduction is a prominent clinical feature, maximalresection of the lateral rectus muscle is combinedwith a small recession of the medial rectus muscle.If movement is excessive in one direction anddeficient in the opposite direction, a maximalweakening procedure on one muscle may be com-bined with a maximal strengthening procedure onthe antagonist. When the rotations are neither ex-cessive nor deficient, the emphasis should beplaced on strengthening rather than on weakeningthe muscle action.

Weakening the action of a normally functioningmuscle tends to restrict movement of the globein the direction of action of that muscle. Largeresections may cause retraction of the globe withnarrowing of the palpebral fissure and large reces-sions may widen the palpebral fissure.

DIAGNOSTIC POSITIONS. The results of carefulmeasurements in the diagnostic positions of gaze(see Chapter 12) also must be considered. In-creases or decreases of the deviation in the variouspositions of gaze are important guidelines in se-

lecting the appropriate procedure. This is espe-cially true in exotropes in whom measurementsin lateral gaze may indicate a smaller angle ofstrabismus than in primary position. The amountof recession of the lateral rectus muscles needs tobe modified accordingly to avoid overcorrections.

The degree of change in the horizontal devia-tion with the eyes in elevation and depressionprovides information regarding the presence orabsence of an alphabetic pattern (see Chapter 19),which may influence the choice of operation.When a vertical deviation is present, measure-ments in the nine diagnostic positions are essentialfor determining the muscle or muscles involvedand, therefore, in choosing the appropriate surgicalprocedure.

Regardless of its usefulness, the prism covertest in the diagnostic positions does not replacethe study of versions. The two tests do not neces-sarily elicit the same information. For example, anincrease of deviation in dextroversion as measuredwith the prism cover test in a patient with esotro-pia may be the result of excess adduction in theleft eye or limitation of abduction in the right eye.Even if the measurement is performed with eithereye fixating, results will remain the same in bothsituations; the prism cover test does not pinpointthe cause of the anomalous muscle actions in thissituation.

FORCED DUCTION TEST. In general, the surgicalprocedure to be performed should be decided onduring the preoperative examinations, and the sur-gical plan should not be changed when the patientis on the operating table and general anesthesiahas caused modification of the deviation. Whenperforming the forced duction test on a patientwho has been given a general anesthetic, the sur-geon must be aware that succinylcholine, a short-acting, depolarizing muscle relaxant used duringendotracheal intubation, causes sustained contrac-tion of extraocular muscles. This effect may lastfor as long as 20 minutes and may interfere withaccurate interpretation of the forced duction test.A nondepolarizing muscle relaxant, which doesnot alter the forced duction test, is suggested asan alternative drug.77

Modification of the original surgical plan isindicated when the forced duction test (see Chap-ter 20) reveals mechanical obstacles not antici-pated preoperatively or when congenital anomaliesor structural changes from previous surgery arefound on exposure of the muscle that were not


evident on clinical examination. The surgeon mustthen change the original plan and remove therestrictions. It follows that the forced duction testmust be used at the beginning and end of eachsurgical procedure and at various stages of theoperation.

For instance, limitation of abduction in an in-fant with esotropia may be caused by weaknessof the action of the lateral rectus muscle or bycontracture of the medial rectus muscles or of theconjunctiva and Tenon’s capsule. In both instancesthe results of clinical examination will be similar,yet surgical management will differ. In the firstinstance, the emphasis of the operation should beplaced on strengthening the action of the lateralrectus muscle; in the second case, this operationwill cause narrowing of the palpebral fissure andlittle improvement of abduction unless the con-tracted medial rectus muscle or conjunctiva is firstrecessed. Another example for application of theforced duction test is the patient in whom a muscletransposition procedure for paralytic horizontalstrabismus or a double elevator or depressor paral-ysis is contemplated. This procedure is successfulonly if mechanical restriction in the field oppositethat of the paretic muscle is eliminated first (seeChapter 20).

Likewise, the position of the eyes after comple-tion of surgery and while the patient is still anes-thetized varies considerably between esotropia andexotropia, even though the eyes may be perfectlyaligned once the patient is awake.204, 205 Thesefindings should be considered by those who attachsignificance, regarding the amount of surgery tobe performed, to the eye position while the patientis anesthetized.6, 23, 177, 230, 242, 243 As a rule, we havefound that assessment of the angle of strabismusunder this circumstance is without value except inpatients in whom strabismus is purely restrictive.In such instances, the eye position is the sameunder general anesthesia as during the wakingstate. This information, in conjunction with theforced duction test, is of diagnostic value.

NEAR POINT OF CONVERGENCE. At one timemuch attention was given to the near point ofconvergence in determining the proper surgicalprocedure for esotropia. The concept was that ac-tion of the medial rectus muscles should not beweakened if the near point of convergence is re-mote, an opinion that in turn was based on theerroneous idea that ocular deviations are causedby inadequate strength of the muscles. Actually,

with few exceptions the medial rectus musclesare always able to contract sufficiently to causemaximal convergence of the eyes. The missingfactor in convergence insufficiency is the nervousimpulse to converge. This impulse arises in anarea of the brain that is spatially separate fromthe area subserving the lateroversion movements.These movements are normal in spite of conver-gence insufficiency, and convergence may be nor-mal, excessive, or defective even though laterover-sions are normal. To be sure, if the medial rectusmuscles are recessed unduly far behind their origi-nal insertion, a mechanical paresis is created, andconvergence and lateroversion will be affected.On the other hand, properly executed operationswill alter the relative position of the eyes, regard-less of the type of procedure, and thus change thestarting position of convergence and divergencemovements. Changes in the near point of conver-gence then will depend on whether the patientexerts the same convergence impulse as before theoperation. If so, the near point should be fartheraway than it was preoperatively in esotropes andcloser in exotropes; however, this is not necessar-ily true because of postoperative adjustments ofinnervation.

Symmetrical vs. AsymmetricalOperations

Some ophthalmologists place much emphasis onthe need for symmetrical operations; that is, thesame type of operation (recession or resection)should be done on homonymous muscles of thetwo eyes. Behind this thought is the belief thatasymmetrical procedures (recession of one mus-cle, resection of the antagonist) often result in anincomitance, although this is by no means alwaystrue. However, routine symmetrical operations arejust as wrong as the exclusive use of any one typeof procedure.

An ophthalmologist who routinely does sym-metrical procedures is automatically assuming thatall patients have a symmetrical abnormality, apremise that is contrary to the facts. In our opin-ion, surgery must be planned on an individualbasis. Clearly, an incomitance should not be cre-ated where one did not exist, but symmetricaloperations should not be performed when asym-metry is the primary anomaly. We therefore rec-ommend symmetrizing rather than symmetricaloperations; that is, symmetry should be main-


tained when it exists and restored when it doesnot exist.

Comitance is desirable, of course, from a func-tional standpoint. Recession-resection operationsare apt to create incomitance, which can be reme-died by operating on the fellow eye. A truly func-tionally harmful incomitance, however, must bedefined. It is doubtful whether incomitance in ex-treme positions of gaze is of major significance,since the eyes rarely if ever move that far duringcasual conditions of seeing (see Chapter 4). Thereis no doubt, however, that postoperative incomi-tance in primary position is functionally detrimen-tal. Such an incomitance is reflected in a changein deviation in primary position with either eyefixating. This may be termed a primary and sec-ondary deviation, but after muscle surgery, it maybe referred to also as a differential angle of squint.

Asymmetrical operations on the yoke musclesof the two eyes also may be performed if thedeviation toward one side is significantly greaterthan toward the other. For example, for an esotro-pia that is 15� or more in levoversion than indextroversion, one may recess the right medialrectus muscle and resect the left lateral rectusmuscle. Such procedures have proved useful inour hands by reducing the deviation in primaryposition and equalizing or reducing the deviationin dextroversion and levoversion.

Amount of Operation

The results of strabismus surgery are not preciselypredictable in terms of prism diopters correctionper millimeter of recession or resection. So-calleddose-response curves or tables, derived from retro-spective analysis of surgical outcomes and listingthe amounts of recession and resections even infractions of millimeters, can be found throughoutthe strabismus literature and give the impressionof accurate predictability of the surgical effect.We have found such data rather useless because ofthe common experience that an identical surgicalprocedure, performed by the same surgeon onseveral patients with apparently similar conditions,may give different results in each patient. At best,dose-response curves or tables may serve as verygeneral guidelines for the less experienced sur-geon. We have included our surgical dosages forthe various forms of strabismus in the appropriatesections of this book, being fully aware, however,of the limitations of such information.

The variability of surgical results depends on

numerous and only partially known factors. Thesensory state of the patient, the operative tech-nique, the manner in which the muscle is exposed,how thoroughly it is freed, its stiffness, whetherthe check ligaments are severed, the placement ofthe sutures, the occurrence of intra- and postopera-tive bleeding, the tendency to form adhesions andscarring, the state of conjunctival elasticity, andthe anatomical variations of muscle insertions arejust some of the variables that may influence theeffect of the operation. Even though it may even-tually be possible to standardize most of theseaspects, additional factors, as yet unknown, mayexist and influence the surgical result. Each sur-geon must establish through periodic review of thesurgical outcomes the approximate effectivenessof the procedure he or she routinely employs fora certain condition and modify the accustomeddosage whenever so dictated by this learning ex-perience.

Despite the foregoing, there are certain empiri-cal rules that are helpful in determining theamount of surgery to perform in each patient.Assuming that the identical operative techniquewas used in each case, the larger the deviationand the more abnormal the rotation, the greaterthe effect will be following a given amount ofsurgery. In older children and adults in whompresumably secondary anatomical changes ofmuscles and fascia have taken place, more exten-sive operations are required than in younger chil-dren with a comparable amount of deviation.

After publication of David Robinson’s classicpaper on quantitative analysis of extraocular mus-cle cooperation in strabismus (1975),240 efforts be-gan to use the aid of a computer to determine thetype and dosage of surgery. Initially, these com-puter predictions were of little value to the practic-ing ophthalmologist, but recent work in this direc-tion has become more promising. The reason forthis is that many of the variables listed above thatdetermine the surgical outcome are now beingincorporated into the calculating process. Some ofthese previously neglected factors are the mechan-ical influence of orbital structures and geometry,muscle and connective tissue mechanics, stabilityof the muscle paths, the muscle pulleys, and in-nervation. The differences between a preoperativecomputer simulation of a surgical procedure andits actual outcome are becoming increasinglysmaller.165, 261 There is reason to predict that thecomputer will play some practical, clinical role inthe future in deciding on the amount and type of


surgery in complex strabismus cases of innerva-tional origin. For strabismus of mechanical cause,such computer predictions have been disappoint-ing.

The recent emphasis on performing surgery foresotropia during infancy has brought new aware-ness of the fact that the globe has not reachedadult size during infancy (see Chapter 3, Table3–2). For this reason, a certain amount of reces-sion or resection is more effective in terms ofreducing the tangency between muscle and globethan when growth of the eye is completed.1, 147

Weakening the action of a muscle (recession)is more effective in reducing the deviation than isstrengthening its action. Relatively larger amountsof resection therefore are required to produce aneffect comparable to that achieved by recession ofthe antagonist.

The sensory state also must be considered. Ifthe patient has a good functional potential forbinocular vision, the surgeon should aim for com-plete alignment of the eyes. In those patients withdeep-seated anomalous retinal correspondence andwithout a functional potential, less extensive sur-gery is required, since a cosmetically acceptableresidual angle is desirable and will enable thepatient to maintain single vision and peripheralfusion by means of anomalous retinal correspon-dence.

Intractable deep amblyopia causes a majorproblem when one is determining the appropriateamount of surgery to be performed. The amountdone under ordinary circumstances may be insuf-ficient and the eye may revert to its original posi-tion. In other patients the deviation will be over-corrected. When deep amblyopia is present,therefore, the patient should be informed of therelative unpredictability of the operation and thepossibility of more than one operation must bementioned.

In view of the foregoing, it is obviously impos-sible to provide for each strabismic condition arecipe by which one can predict the correction tobe obtained from a specific amount of recessionor resection. Nevertheless, on the basis of clinicalexperience and with the surgical technique that weuse, the following guidelines have been founduseful. A minimal amount of combined resection-recession in one eye can be expected to correct20� to 25�, and a maximal resection-recessionprocedure may correct 40� to 60� of esodeviationor exodeviation. A minimal recession of both me-dial or both lateral rectus muscles corrects 15� to

20�, and a maximal recession of these musclescorrects up to 50� of an esodeviation or exodevia-tion. The minimal and maximal amounts of reces-sion and resection for each muscle are discussedelsewhere in this book in connection with specificconditions. The amount of surgery must be distrib-uted between the muscles according to our conceptof symmetrizing their action, as outlined in thepreceding discussion, and according to the size ofthe deviation.

Prism Adaptation Test

It has been observed that the eyes of some patientsmay return to the preoperative angle after surgicalcorrection on the basis of anomalous retinal corre-spondence or of anomalous fusional movements(see Chapter 11) or that the preoperative angle ofstrabismus may increase or reestablish itself afterneutralization with prisms. Such patients are saidto be ‘‘eating up’’ the prismatic correction. On thebasis of these observations some authors advocatedeliberate surgical overcorrection when the angleincreases significantly after prismatic compensa-tion. Indeed, the preoperative use of prisms topredict the amount of surgery has been advocatedsince the 1960s.7, 8, 110, 116, 124, 295 Improved surgicalresults were reported when the increase of thedeviation under the influence of correcting prisms(prism adaptation) was taken into account whendetermining the surgical dosage. A multicenter,prospective, and randomized study was publishedin 1990229 that reported the efficacy of prism adap-tation in the surgical management of acquiredesotropia. This study showed that the success ratein patients whose angle increased under the influ-ence of prisms base-out was higher (see also Oht-suki and coworkers205) after augmented surgery(89%) than when conventional surgery was per-formed (79%). In a 1-year outcome study of theoriginal patient group, prism responders operatedon for the adapted esotropic angle had a satisfac-tory motor outcome more often (90%) than thoseoperated on for the entry angle (75%).237 However,Greenwald,94 using a different statistical approach,found that the overall motor success rate for thestudy’s adaptation group was only 75% vs. 74%in the conventionally managed group.

There remain additional questions regarding theprism adaptation study in terms of the nosologichomogeneity of the study group and the influenceof the sensorial state of patients undergoing prismadaptation. Moreover, there are no clear directions


as to how much the surgical dosage needs to beaugmented when prisms are ‘‘eaten up.’’ No dueconsideration has been given to the fact that chil-dren tend to compensate for stronger prisms thanadults, which may affect the long-term outcomeof surgery augmented on the basis of prism adap-tation. These considerations, as well as the cost ofprismatic spectacles in patients who ordinarily donot wear glasses, the general lack of compliancewith wearing prismatic spectacles at home, andthe necessity for repeated patient visits duringwhich the prismatic power must be adjusted, arereasons why we have not adopted the prism adap-tation procedure to determine the dosage of sur-gery.

Operations to Weaken the Actionof a Muscle

As mentioned elsewhere in this chapter, recessionsreduce the deviation more per millimeter than doresections of the same amount. Recessions do notdisrupt the action of an overacting muscle, but ifa muscle does not overact preoperatively or if itis recessed too far, its action may indeed be undulyweakened.

Excessive weakening of the action of a muscleusually is attributed to the loss of rotational forceor torque. Torque acts on the tangential point ofthe muscle, which, in the case of the medial rectusmuscle, lies 6.27 mm in front of the equator whenthe globe is in primary position. The rotationalforce is most effective when it is applied tangen-tially. When the muscle is recessed, thus alteringits tangential point, the direction of the appliedforce changes and the muscle loses some of itsmechanical effect. Adelstein and Cuppers1 haveshown that the effect of a recession on the arc ofcontact depends on the diameter of the globe,which varies in patients of different age groups.Moreover, normal variations in the distance be-tween the limbus and insertion of a muscle mayadd an additional variable to the effect of a stan-dard recession procedure.109

Beisner10 developed a formula by which theloss of torque with various degrees of recessioncan be determined. He found that this loss, thoughreal, is less than generally assumed. From thefamily of curves derived by Beisner, one can seethat an 8-mm recession of a medial rectus musclereduces the torque by only 1.5% in primary posi-tion and by 10% with 10� adduction. Beisner be-lieves that the loss of torque is a secondary reac-

tion and that the primary cause of postoperativeunderaction is loss of contractile force caused byshortening of the muscle. This physiologic rela-tionship between muscle force and muscle lengthis known to exist.

Beisner’s conclusions are well founded, but inaddition to torque and muscle length reduction, athird factor must be considered. Not only has theinsertion been set back in the operation but themuscle is no longer quite in situ, since many of thedampening and supporting structures have beensevered. Their removal indubitably adds to theeffect of surgery.

RECESSION OF HORIZONTAL RECTUS MUS-

CLES. Recession of the medial rectus muscles foresotropia should be restricted to a maximum of 8mm. Larger recessions are likely to disturb thebalance between opposing muscle forces: the un-opposed lateral rectus becomes tight and pulls theeye toward abduction. This effect is sometimesdesirable, for instance, when shifting the null posi-tion in congenital nystagmus from a peripheralgaze position to the primary position (Chapter 23).However, if both the medial and lateral recti arerecessed as much as 12 mm, the balance betweenthe opposing muscle forces remains undisturbedand the resulting motility deficit in lateral gaze isclinically negligible.

If both medial rectus muscles are operated on,they are often recessed the same amount; however,this is not mandatory, and again considerationshould be given to the individual problem. If ad-duction in one eye is significantly more excessivethan that in the fellow eye, one may recess themedial rectus of that eye, say, 6 mm, and recessonly 3 mm in the other eye. As a rule, a recessionof the medial rectus muscle is more effective thanthe same amount of recession performed on alateral rectus muscle. Recessions of the verticalrectus muscles are more effective than when theyare performed on the horizontal rectus muscles.

Recessions of both lateral rectus muscles ofless than 5 mm are of little use in the treatmentof exotropia. Unilateral or bilateral lateral rectusmuscle recessions of 6 to 8 mm generally arerequired. In adults with exodeviations exceeding70�, we recess the lateral rectus muscle as muchas 10 to 12 mm behind its insertion and have neverhad more than moderate restriction of abductiondevelop postoperatively. One must remember thateven though this puts the insertion behind the


anatomical equator of the eye, the lateral rectusmuscle will remain in contact with the globe be-hind the equator (functional equator) and thuscontinue to exert rotational force on contraction.This is the reason this operation has a greatereffect when performed on the medial than on thelateral rectus muscle.

In patients with long-standing strabismus whohave a large and especially fixed angle with con-tracture of the conjunctiva and Tenon’s capsule,the effect of recessing a rectus muscle can beaugmented by recessing these tissues as well (seep. 616).

RECESSION OF VERTICAL RECTUS MUSCLES.

Surgery on the vertical rectus muscles has becomea routine procedure in our time and is very effec-tive and free of complications, provided certainprecautions are taken and the amount of surgeryis not excessive. Great care must be taken indissecting the inferior rectus muscle from all itsfascial attachments to Lockwood’s ligament, sincedirect fibrous connections exist between the mus-cle and the tarsus of the lower lid. Failure tometiculously dissect these connections causes pto-sis of the lower lid with resection or retraction ofthe lower lid when a recession of the inferiorrectus muscle is performed. According to Jampol-sky,128 recession of the lower lid can be avoidedby reattaching the capsulopalpebral head of therecessed inferior rectus to that muscle 15 mmfrom the limbus. This approach has been modifiedby others.144, 212, 270 We have been unsuccessful inconsistently avoiding lower lid retraction usingthese or other methods to reattach the capsulopal-pebral head.

The anatomical connections between the leva-tor palpebrae and the superior rectus muscle areless critical in operating on the latter muscle. Rela-tively large amounts of recession (e.g., 8 to 9 mmfor dissociated vertical deviations) or resection ofthe superior rectus muscle are tolerated well with-out causing changes of the upper lid position.

Since surgery on the vertical recti is more ef-fective in terms of millimeters recession or resec-tion per prism diopter correction and more predict-able than surgery on the horizontal recti, weinfrequently recess or resect the vertical recti morethan 5 mm except in dissociated vertical devia-tions, endocrine ophthalmopathy, or fibrosis of anextraocular muscle.

SLANTING OF THE RECTUS MUSCLES. Fink71

mentioned that ‘‘some surgeons’’ tenotomize the

nasal fibers of the superior rectus muscle or ad-vance the superior border and recess the inferiorborder of the medial rectus muscle to treat ex-cyclotropia. However, he provided no details orcase reports to prove the effectiveness of thisprocedure. Lyle150 reported, paradoxically, that ad-vancing the temporal and recessing the medialborders of the inferior rectus muscle reduces ex-cyclotropia when, in fact, it should have increasedit. Spielmann268 introduced slanting of the rectusmuscle insertions to treat cyclotropia or a head tiltcaused by congenital nystagmus with a neutralzone in a tertiary position. For instance, by re-cessing only the nasal portion of the right superiorrectus, the inferior portion of the right medial, thetemporal portion of the right inferior, and thesuperior portion of the right lateral rectus muscles,the right eye is incycloducted by approximately10�. The same operation performed on the lefteye will produce an excycloduction of the sameamount. We can confirm the effectiveness of thisoperation but have abandoned it for simpler ap-proaches, such as a horizontal transposition of thevertical197 or vertical transposition of the hori-zontal rectus muscle.53

Nemet and Stolovitch182 suggested resecting theupper border and recessing the lower border ofthe medial rectus muscles in convergence insuffi-ciency to make the operation more effective atnear than at distance fixation.

POSTERIOR FIXATION SUTURE. Cuppers,49 in1974, popularized a new operation termed Faden-operation. A similar, though not identical, opera-tion was actually described earlier by Peter220 in1941, but it found little resonance at that time.With this operation, the action of a rectus muscleis selectively weakened in its primary field ofaction without disturbing the balance between ag-onist and antagonist in other positions of gaze.This is accomplished by suturing the muscle tothe sclera behind the equator and thus creating anew insertion, posterior to the anatomical insertion(Fig. 26–1).

The word faden is German for ‘‘thread’’ or‘‘suture’’ and is derived from the use of sutures toattach the muscle to the sclera. But sutures areused for most types of muscle surgery and hencethe term Fadenoperation is rather nonspecific.Moreover, it had been used previously in the olderGerman literature to describe traction sutures usedto pull an eye operated on temporarily into anovercorrected position.45, 57 We suggested, there-


FIGURE 26–1. Posterior fixation of the superior rectusmuscle weakens the effect of contraction of that musclein elevation. With this operation the balance between thesuperior rectus muscle and the opposing inferior rectusmuscle remains undisturbed in primary position and de-pression. (From von Noorden GK. Posterior fixation su-ture in strabismus surgery. In symposium on strabismustransactions of the New Orleans Academy of Ophthal-mology. St Louis, Mosby–Year Book, 1976.

fore, that this operation be designated posteriorfixation suture or retropexy of an extraocular mus-cle.189 Even more precise, though considered bysome as too ponderous, is retroequatorial myo-pexy. In view of these more descriptive and preciseterms there is no justification for adopting ‘‘Faden-operation’’ into the English language as has unfor-tunately become customary in the contemporaryliterature.

There are several mechanisms that may con-tribute to the effectiveness of this operation:

1. The ability of a rectus muscle to rotate theeye depends on the leverage existing be-tween the center of rotation (CR) and theline of pull of the muscle at the tangentialpoint (Pt) (Fig. 26–2A). By suturing themuscle behind the equator, the length of themoment arm (m) of this lever system isdecreased and more muscle force (��)

is now required to rotate the globe the sameamount (Fig. 26–2B). The further retro-equatorially the muscle is fixated, thegreater the muscle force must be to maintainthe same rotational effect on the globe. Thisclassic explanation of the torque exerted bya rectus muscle has been challenged byClark and coworkers39 who, in 1999, dem-onstrated by axial magnetic resonance im-aging (MRI), that a significant change intorque of a retroequatorially fixated hori-zontal rectus muscle actually does not occur.In fact, the angular displacement from tan-gency is much less than one would predictgeometrically. They point out that the classic‘‘arc of contact’’ concept on which the ge-ometry shown in Figure 26–2 is based mayhave to be changed since it does not con-sider the nonlinear paths of the rectus mus-cles caused by pulleys and during musclecontraction.

2. Since the innervational requirement of aposteriorly fixated muscle for a given rota-tion of the globe increases and since there isequal innervation of yoke muscles (Hering’slaw; see p. 64), the operation increases in-nervation to the yoke muscle of the felloweye. For instance, by performing this opera-tion on the superior rectus muscle of thenonparetic eye in a patient with an elevatorparesis, the innervational requirements to el-evate the eye operated on increase. In-creased innervation will also flow to the

FIGURE 26–2. Mechanical effect of retroequatorial mus-cle fixation. For explanation, see text.


FIGURE 26–3. The innervation required to elevate the fixating nonparetic eye is insufficient toelevate the paretic eye in a patient with elevator paresis of the left eye, A, A posterior fixation ofthe superior rectus muscle of the fixating right eye increases the innervational requirement to elevatethat eye. B, According to Hering’s law of equal innervation, increased innervation will flow also tothe yoke muscle in the fellow eye and elevation of the paretic eye improves.

paretic elevators of the fellow eye and im-prove their elevating force (Fig. 26–3). Thisprinciple is, of course, only applicable topatients who habitually fixate with theirnonparetic eye.

3. A mechanical restriction occurs from a ‘‘re-verse leash effect’’126 (Chapter 20), which iscaused by the retroequatorially fixated andshortened medial rectus muscle pushingagainst the retrobulbar tissues as the eyeadducts.198, 213 This restriction of adductioncan be demonstrated with the forced ductiontest and may cause a jerk nystagmus ofthe abducted fellow eye so that the clinicalpicture resembles that of an internuclear pa-ralysis.198 Clark and coworkers39 have pro-vided further information on the nature ofmechanical restriction of ocular rotation fol-lowing posterior fixation. They suggestedthat the restriction that also occurs, thoughto a lesser degree, in abduction after poste-rior fixation of the lateral rectus muscle oc-curs because the muscle pulley is deformedand stretched behind the suture.

4. During the operation the muscle is consider-ably stretched, which causes its elongationproximal to the myopexy.

5. Since the segment of the muscle between itsanatomical and new insertions is function-ally inactivated, the contractile elements ofthe muscle are shortened and the effective-ness of a muscle contraction is decreased.

The posterior fixation suture has found a defin-itive place in our surgical armamentarium.12, 28, 49,

50, 54, 179, 189, 190, 193, 196, 269 In our experience the opera-tion is most effective when performed on themedial rectus, less effective on the vertical rectus,and least effective on the lateral rectus muscle.We use it frequently in the treatment of incomitantstrabismus in patients who are orthotropic in pri-mary position but have diplopia in a peripheralposition of gaze. For instance, a patient with amild right abducens paresis will have single binoc-ular vision in primary position and levoversion butexperience uncrossed diplopia in dextroversion. Aposterior fixation suture applied to the left medialrectus muscles will cause slight limitation of ad-duction of that eye without compromising normalbinocular vision in primary position. This adduc-tion limitation offsets the limitation of abduction,and single binocular vision will be present in allgaze positions. In other words, a paresis is treatedby causing a slight and clinically insignificantparesis of the yoke muscle. Other applications


include nystagmus dampening by convergence(nystagmus blockages syndrome), and esotropiawith a variable angle.

It was originally thought that the operation hasno effect on the position of the eyes in primaryposition. Although this still holds true in patientswho are orthotropic in primary position, posteriorfixation of the medial rectus muscles will reduceesotropia in primary position by decreasing theeffectiveness of an increased adduction innerva-tion. If a significant deviation exists in the primaryposition and further weakening of muscle actionis desired in the field of action of a medial rectusmuscle, the operation may be combined with amuscle recession. We have also recommended thisoperation as a viable alternative to marginal myo-tomies of the medial recti in patients with a persis-tent esotropia in spite of previously performedmaximal recession of the medial recti and resec-tions of the lateral recti.193 Klainguti136 pointedout that a desirable cyclorotational effect can beobtained by placing the posterior fixation suturesobliquely into the inferior rectus muscle; fixatingthe nasal aspect of the muscle closer to the limbusthan the temporal one reduced excyclotropia, espe-cially in downward gaze.

Since a conventional posterior fixation sutureis not adjustable, A. B. Scott253 suggested resectinga muscle before recessing it by an amount equalor greater than the resection and then placing iton a hang-back adjustable suture. This alternativeto a posterior fixation should be kept in mind iffor some reason retroequatorial suture placementis technically difficult or for other reasons (e.g.,scleral thinning) is inadvisable (see also Bock andcoworkers20).

WEAKENING THE ACTION OF THE INFERIOR

OBLIQUE MUSCLE. Weakening the action of theinferior oblique muscle can be achieved in manyways: the muscle may be myotomized, disinserted,denervated, anteriorly tranposed, extirpated, length-ened by marginal myotomy, recessed, or myecto-mized at its origin or through a conjunctival inci-sion in the temporal inferior quadrant between itsinsertion and the inferior rectus muscle. With theexception of a myotomy or myectomy near the originof the muscle—a technique that has been largelyabandoned—all other procedures are currently inuse, each strabismus surgeon championing one orthe other favorite approach.43, 48, 63, 86–88, 216, 218, 276

MYECTOMY. Having tried most of these meth-ods, each of which has its advantages and disad-

vantages, over the years, the senior author hasfound that a myectomy through a conjunctival inci-sion in the inferior temporal quadrant, as illus-trated in Figure 26–11, consistently gave the mostpredictable results. This procedure is effective,fast, technically simple, and intra- or postoperativecomplications are exceedingly infrequent in ourexperience (see also Mulvihill and coworker173).For these reasons the myectomy has evolved forone of us (GKvN) as the procedure of choice forweakening the action of the inferior oblique mus-cle. Once the presence of a significant increasedelevation in adduction has been determined, a my-ectomy of the inferior oblique muscle may reducethe hyperdeviation in its field of action and alsomay reduce significantly a hyperdeviation in pri-mary position. Moreover, if the action of the an-tagonistic superior oblique muscle has been im-peded by a tight inferior oblique muscle, thefunction of the superior oblique muscle may im-prove after an inferior oblique weakening proce-dure. The average reduction of a hyperdeviationby inferior oblique myectomy in the field of actionof that muscle in primary position and in the fieldof action of a paretic superior oblique muscle is11.5� and this effect increases with the size of thepreoperative deviation.284 Weakening the action ofthe inferior oblique muscle tends to reduce oreven eliminate excyclotropia, which is invariablypresent when this muscle overacts. Because of itsabductive effect, a weakening procedure per-formed on the inferior oblique muscle alters thehorizontal position of the eyes in upward gaze(see Chapter 19). The effect of this procedure onthe horizontal position of the eyes in primaryposition is negligible.274 An overcorrection follow-ing surgery on this muscle is rare but tends tooccur when a weakening operation is performedon a normally acting muscle or when the upshootin adduction is only minimal.

In our experience, as well as that of others,231

a unilateral inferior oblique weakening procedureshould be performed only after it is clearly estab-lished that elevation of the adducted fellow eye isnormal. If this point is overlooked, hypertropiaof the eye not operated on invariably will occurpostoperatively.

The adherence syndrome described by Parks217

in 13% of myectomies performed at the insertionand in 2% of disinsertions of the muscle consistsof a hypotropia greater in abduction than adduc-tion and restricted elevation with a positive forcedduction test. It is caused by a reattachment of the


muscle into ‘‘fatty Tenon’s tissue’’ and ‘‘prolifera-tion of the fibrofatty tissue in the inferior temporalarea extending up and attaching to the insertionand capsule of the inferior rectus muscle.’’217 Inperforming myectomies of the inferior oblique inthe inferior temporal quadrant for the past 40years, the senior author has encountered this com-plication only once

RECESSION. Many strabismologists (includingthe junior author) prefer to recess rather than my-ectomize this muscle. It has been argued that thisoperation is reversible in case of an overeffect andcauses less bleeding and swelling. As mentionedabove, an overcorrection has not been a problemfor the senior author, provided this operation wasnot performed on a normally acting inferioroblique muscle. The ability to modulate the effectof surgery in asymmetrical cases of increased ele-vation in adduction is a good reason why recessionis preferred by some. Interestingly, limitation ofelevation in abduction of the eye operated on withsecondary upshoot in adduction of the contralat-eral eye has been reported as a complication notonly of anteriorization but also of recession of theinferior oblique muscle.142 A recession of onlythe anterior part of the inferior oblique insertiondecreases the excycloduction effect of that muscleand an advancement increases it.41 Likewise, re-cession of its posterior aspect will decrease eleva-tion in adduction without having an incyclorota-tory effect.

ANTERIORIZATION. Transposing the insertionof the inferior oblique muscle to a position lateralto the insertion of the inferior rectus muscle65, 272,

273, 276 has gained some popularity in recent years.However, this procedure is not without its prob-lems as it may produce changes in the palpebralfissure145a or a limitation of elevation in abductionwith secondary contralateral upshoot in adductionthat may require additional surgery.145, 169, 277 Mimsand Wood170 suggested that this complication canbe avoided by attaching the posterior fibers of theinferior oblique muscle not more than 2 mm lat-eral to the inferior rectus insertion site. In compar-ing the results of myectomy vs. anterior position-ing, one group of authors found the latterprocedure more effective.29 On the other hand,such differences were not noted in other studiesof a much larger patient group.35, 172 In view of theefficacy, lack of complications, and ease withwhich myectomy or recessions are performed, wesee no reason to abandon either of these proce-

dures in favor of anteriorization of the inferioroblique muscle.

WEAKENING THE ACTION OF THE SUPERIOR

OBLIQUE MUSCLE. As in the case of surgeryon the inferior oblique muscle, numerous surgicalprocedures have been used to weaken the actionof the superior oblique muscle. The tendon maybe recessed, lengthened with silicone expander,severed, or a piece excised. The loose tissue sur-rounding the tendon may be left intact or severedalong with the tendon. Over the years, each ofthese procedures has found its strong proponents.The impression has been created that by includingor excluding the sheath (which some authors be-lieve is not a true sheath but rather a reflection ofTenon’s capsule; see p. 467) in the operation, orby performing the tenotomy closer to or fartheraway from the trochlea, the surgical effect can bemodified. In our experience, this has not beenso. Once the continuity of the tendon has beencompletely disrupted, the effect will be the sameregardless of where the tenotomy is done orwhether the sheath, or whatever one may chooseto call it, is sectioned or left intact. For this reason,and after having tried all procedures, we prefer toperform a tenectomy (including the sheath) mid-way between the insertion and the trochlea in theupper nasal quadrant or a recession.

TENECTOMY. As is true with weakening pro-cedures on the inferior oblique muscle, it is diffi-cult to predict precisely the amount of correctionin terms of prism diopters achieved by tenectomyof the superior oblique muscle. Nevertheless, theoperation is extremely effective in reducing thevertical deviation in downward gaze, an A pattern(see Chapter 19), or an incyclotropia. Overcorrec-tions rarely occur, but if they do, they may causesevere functional problems in downward gaze. Toavoid overcorrections, perform tenectomy only inthose patients in whom a significantly increasedelevation in adduction can be demonstrated un-equivocally before surgery. The exception to thisrule is a tenectomy in a patient with Brown syn-drome.

RECESSION. In patients with milder yet func-tionally significant increased depression in adduc-tion, we prefer, because of its reversibility, torecess the tendon, as proposed by Caldeira.30, 31 Itis of interest, however, that a comparison of surgi-cal results in patients treated with tenotomy orrecession of the superior oblique tendon showedboth procedures to be equally effective.27


Recession of the anterior aspect of the superioroblique tendon decreases incycloduction and anadvancement increases it.41 A tenotomy of theposterior fibers selectively weakens the verticalaction of the muscle without altering its cycloduct-ing effect. This procedure has been successfullyemployed to collapse an A-pattern with mild tomoderate overaction of the superior oblique mus-cles.259, 288

As an alternative to recession of tenectomyof the superior oblique muscles, Mombaerts andcoworkers171 have advocated surgical luxation ofthe tendon out of the trochlea or of the trochleaand tendon and reported encouraging results inacquired Brown syndrome and apparent superioroblique overaction. This approach must await fur-ther studies to assess its value in comparison withother superior oblique muscle weakening proce-dures currently in use.

SILICONE EXPANDER. Rather than recessingthe tendon, Wright305 introduced a silicone ex-pander to lengthen it. He reported superior resultswith this method in Brown syndrome (see p. 471)when compared with tenectomy.307, 308 Other au-thors have also reported favorable results with thesilicone expander technique in Brown syndrome275

as well as in superior oblique overaction withan A-pattern.224, 256 However, this operation is notwithout its problems.298 We had occasion to reop-erate on several patients for extrusion of the im-plant. Moreover, the expander does not alwaysprotect against a subsequent symptomatic superioroblique paralysis.224 Mechanically, the lenghteningof a tendon with an expander is not much differentfrom performing a large recession of the tendonand the latter is a much simpler procedure. Weprefer recession or a tenectomy rather than im-planting foreign material near the superior aspectof the globe, an area that in our surgical experi-ence is particularly prone to form adhesions andpostoperative reaction.

MARGINAL MYOTOMY. Unlike a recession orposterior fixation suture, which reduces the actionof a muscle by decreasing its rotational force onthe globe, the marginal myotomy entails actualweakening of the muscle by reducing the numberof contractile elements without changing its arc ofcontact with the globe. This procedure is effectivein further reducing the action of an already maxi-mally recessed rectus muscle or one that cannotbe recessed because of extremely thin sclera, animplant, exoplant, or an encircling tube placed

directly behind its insertion during prior retinalsurgery.107 A review of 18 patients with persistentesotropia after maximal recession of the medialrectus muscle, in whom we performed a marginalmyotomy of these muscles as a second procedure,showed a mean improvement of 9� at distance andof 21� at near fixation after a follow-up of 3years.68 The wide range indicates that the resultsof marginal myotomies are rather unpredictable.

A disadvantage of marginal myotomy is itsirreversibility. In the case of a patient with persis-tent esotropia after maximal recession of both themedial rectus muscle and resection of both lateralrectus muscles, we found that application of poste-rior fixation sutures to the medial rectus muscleswas an effective alternative procedure to marginalmyotomy of the medial rectus muscles.193

Operations to Strengthen theAction of a Muscle

To enhance the action of a muscle, one mayshorten its length by tucking or resecting a portionof the tendon or, in the case of the rectus muscles,by advancing the line of insertion toward the lim-bus. A combined resection and advancement of amuscle is the most commonly performed operationto enhance muscle action. In terms of prism diop-ters of correction per millimeter of resection, asingle resection usually is less effective than asingle recession. Advancements, which have beenrather neglected in recent years, are effective inincreasing and stabilizing the results of a resec-tion. Excessive resection may mechanically re-strict movement of the globe in the opposite direc-tion and therefore must be avoided.

HORIZONTAL RECTUS MUSCLES. The minimalamount of resection performed on the medial rec-tus muscle is 4 mm, and the maximal amountrarely exceeds 7 or 8 mm. We infrequently resectthe lateral rectus muscle less than 4 mm or morethan 10 mm. When more correction is desired, themuscle is advanced toward the cornea.

VERTICAL RECTUS MUSCLES. In strengtheningprocedures, as in weakening operations, the rela-tionship of the vertical rectus muscles to the lidstructures must be taken into account. We rarelyresect the vertical rectus muscles less than 2 mmor more than 5 mm. As mentioned, in terms ofprism diopter correction per millimeter of surgery,a resection of the vertical rectus muscle is more


effective than a comparable procedure on the hori-zontal rectus muscles.

INFERIOR OBLIQUE MUSCLE. Many technicalproblems occur with the operation to strengthenthe action of the inferior oblique muscle. Resec-tion of the inferior oblique muscle at its insertionand advancement, in particular, must be performedwith great care to avoid injury to adjacent struc-tures such as the fovea.41 Moreover, in our experi-ence, this procedure is notoriously ineffective inimproving ocular motility in the field of action ofthis muscle. For this reason, we prefer to weakenthe action of the superior rectus muscle in thefellow eye or, in the case of inferior oblique paral-ysis, to perform a tenectomy of the ipsilateralsuperior oblique muscle.208

SUPERIOR OBLIQUE MUSCLE. A tuck of thesuperior oblique tendon is effective in improvingdepression of the adducted eye and in counter-acting excyclotropia. One complication of this op-eration is temporary inability to elevate the ad-ducted eye, similar to Brown syndrome (seeChapter 21). Even though this overeffect normallysubsides after several months, we observed perma-nent restriction of ocular motility in upward gazein several instances. The length of tendon includedin the tuck ranges from 6 to 12 mm and thedecision of how much to tuck depends not onlyon the degree of hypotropia of the adducted eyebut also on the tendon’s tightness. As a rule, weperform larger tucks in congenital superior obliqueparalysis than in acquired superior oblique paraly-sis where the tendon is often tight. The tightnessof the tendon must be ascertained by the rotationalduction test (see p. 423) and determines the sizeof the muscle tuck. By keeping these points inmind, a postoperative limitation of elevation inadduction (iatrogenic Brown syndrome) can usu-ally be avoided.

Combined Recession-ResectionOperation

Weakening of an agonist combined with strength-ening the action of the antagonist in the sameoperative session adds greatly to the effectivenessof each procedure and tends to stabilize the surgi-cal result. Clinical experience supports the conceptthat each resection operation reduces the amountof contracture that normally occurs in the recessedantagonist. Thus a resection is often added not so

much on its own account but rather as a means toensure the effectiveness of the recession.281

The amount of this surgery depends, as always,on the individual case, and one should determinewhether a recession supported by a resection or aresection supported by a recession is the moreappropriate approach. The answer is determinedfrom the behavior of the rotations and frommeasurements of the deviation.

In comitant strabismus, we usually do not per-form more than a 5-mm recession of a medialrectus muscle combined with an 8- to 10-mmresection of a lateral rectus muscle for esotropiaand an 8-mm recession of a lateral rectus musclecombined with a 7-mm resection of the medialrectus muscle for exotropia (for an exception, seep. 573). When a combined operation of the verti-cal rectus muscles is indicated, we usually recessone vertical rectus muscle 3 mm and resect itsantagonist 4 mm. Combined procedures may alsobe performed on the oblique muscles (e.g., tuckingof the superior oblique and a myectomy of theantagonistic inferior oblique muscle) but are indi-cated only if the hypertropia in the paretic field ofgaze exceeds 25� (see p. 449).

Single vs. MultipleProcedures

Many exposures to general anesthesia clearlyshould be avoided, and the eyes should be alignedwith a minimum of operations. With this in mind,it is appropriate to operate on more than one setof muscles during one surgical session, and inlarge deviations we also operate on all four hori-zontal muscles in the two eyes.

We maximally recess both medial rectus mus-cles and resect one lateral rectus muscle to correctesodeviations exceeding 50� and operate on allhorizontal rectus muscles if the deviation exceeds75�. Likewise, a recession of both lateral rectusmuscles combined with resection of one medialrectus muscle may be considered for an exodevia-tion of more than 50�, and all four horizontalmuscles can be operated on if the deviation mea-sures more than 75�.

When small incomitant vertical deviationsalong with comitant horizontal deviations are pres-ent, it is undesirable to attempt to correct bothdeviations at the same time. A relatively smalldeviation in one direction often is influenced bythe surgical correction of the deviation in the other


direction. It is wise therefore to permit some timeto elapse between procedures to determine theeffect of the correction of the horizontal deviationon the vertical deviation. Small comitant verticaldeviations associated with horizontal deviationsrespond well to vertical transpositions of the hori-zontal rectus muscles at the time of their recessionor resection (see p. 612).

For a large vertical deviation, which may bethe cause of the horizontal deviation by impedingbinocularity, an attempt should be made first tocorrect the vertical deviation. If the vertical devia-tion is smaller than the horizontal deviation, thehorizontal deviation is corrected first. Additionaloperative procedures depend on the outcome ofthe initial operation.

The presence of an A or V pattern with in-creased elevation or depression in adduction altersthe rule for correcting horizontal and vertical devi-ations in separate operations. In such cases, wecombine horizontal and oblique muscle surgery inone procedure, as described in Chapter 19.

Preparation of Patient andParents for Surgery

A great deal of unnecessary fear and bewildermentcan be avoided by appropriate psychological prep-aration of the parents and patient. The strabismussurgeon must realize that the first mention of sur-gery to the parents of a strabismic child may causeconsiderable anxiety, and the subject should beapproached gently and in anticipation of the par-ents’ possible reactions, preferably with the childoutside the examination area. The operationshould be explained briefly (without going intounnecessary details) to dispel fears and the aston-ishingly frequent notion that the eye is temporarilyremoved from the orbit during surgery or thatsurgery is performed with laser beams. We oftensense a mild disappointment when we explain thatthere is no need for lasers. The parents also shouldbe told how much, if any, postoperative discomfortcan be expected. One should make a point ofmentioning which eye is to be operated on, butqualify this by saying that plans sometimes haveto be altered during the operation. In the case ofalternating strabismus with equal visual acuity andessentially normal versions, for which it reallydoes not matter which eye is operated on, thesurgeon should make a choice before surgery andinform the patient or parents accordingly. Nothing

is more difficult to explain to a patient or theparents why, in some conditions, it makes nodifference on which eye the surgery is performed,or why the right eye was operated on when thesurgeon had previously mentioned it would be theleft eye! Just in case unusual findings at the timeof surgery, such as extensive scarring from previ-ous operations, unexpected anatomical anomalies,or absence of a muscle, necessitate a change ofplans, it is prudent to obtain permission to operateon either eye before surgery.

Finally, it is a grave mistake to be overconfi-dent in predicting the outcome of strabismus sur-gery. The late Dr. Alan C. Woods, when ques-tioned by an anxious mother about whether hecould guarantee the result of strabismus surgeryon her child, replied, ‘‘Madam, in order to do thatI would have to be God or a damned fool, and Iam neither.’’ The possibility of an overcorrectionor undercorrection and the need for more than oneoperation should be mentioned. If this is ade-quately explained, most parents will maintain con-fidence in the surgeon rather than question his orher ability if another operation becomes necessary.

Anesthesia

General Anesthesia

The globe and its adnexa can be completely anes-thetized locally, so that operations on the extraocu-lar muscles can be performed painlessly. Everyadult should be informed of this possibility andgiven the choice between local and general anes-thesia. Children and apprehensive or nervous adultpatients should be given a general anesthetic. Wealways use general anesthesia for patients whoundergo reoperations, surgery on the inferior rec-tus muscle for endocrine ophthalmopathy, or sur-gery on the muscles of both eyes.

Most hospitals in which eye surgery is per-formed have an anesthesiologist available, whichrelieves the ophthalmologist of a serious responsi-bility. The surgeon should abide by the sugges-tions and rules of the anesthesiologist, who shouldalso be acquainted with the patient and suggestthe choice of anesthetic. However, the ophthalmol-ogist must be aware of the details of the anesthe-sia. In most hospitals the anesthesiologist willinsist on intubating the patient, even the youngestinfant.

Needless to say, a patient undergoing elective


surgery must be in good health. A physical exami-nation before the operation is mandatory and inchildren is best performed by their pediatrician. Ithas been recommended that at least 1 month beallowed between the last upper respiratory infec-tion and the date of surgery since intra-anestheticpulmonary dysfunction has been observed whenthis rule was violated.157

As mentioned on page 570, the position of theeyes during surgical levels of anesthesia is differ-ent from that during the waking stage in mostpatients with strabismus of nonmechanical origin.In esotropes in particular, the eyes appear to beless esotropic or even exotropic when innervationof the extraocular muscles is suspended. The inex-perienced surgeon is easily intimidated by thisobservation and will perform less surgery thanoriginally intended. This will produce an under-correction, of course, and reoperation will becomenecessary.

Local Anesthesia

To obtain akinesia of the lid, we inject 2 mL of1% lidocaine over the condyloid process of themandible, according to the method of O’Brien.

FIGURE 26–4. Instruments for strabismus surgery. Upper row from left to right: Stevens tenotomyhooks (2); Graefe muscle hooks No. 1 (2); Graefe muscle hooks No. 3 (2); Jameson muscle hooks(2); Castroviejo suturing forceps 0.3 (2); Castroviejo suturing forceps 0.5 (2); Castroviejo needleholders, heavy model (2); mosquito hemostats (2); Jameson resection clamps, right and left, childsize (2); Jameson resection clamps, right and left, adult size (2). Lower row from left to right:Stevens tenotomy scissors, curved (1); Stevens tenotomy scissors, short blades, straight (1); Wescotttenotomy scissors, blunt point (1); smooth tying forceps (2); Castroviejo caliper (1); Lester-Burchspeculum (1); Sauer infant speculum (1); Burch tendon tucker, modified by von Noorden (1)192; wetfield cautery forceps (1); serrefines (4); Nugent utility forceps (1); Desmarres lid retractors, sizes 1,2, 3 (3); malleable neurosurgical retractor (1).

Local anesthesia is then induced with severaldrops of 0.5% proparacaine hydrochloride (Oph-thaine), followed by an injection of 1% lidocaineunderneath Tenon’s capsule in the quadrant inwhich surgery is performed. The sub-Tenon’sspace is entered with the injection needle 3 mmbehind the limbus, anterior to the muscle insertion.The injected solution will rapidly spread, bal-looning conjunctiva and Tenon’s capsule into allfour quadrants. A retrobulbar injection is rarelynecessary. If the tissue is handled gently and ex-cess traction of the muscle is avoided, the patientwill tolerate muscle surgery under local anesthesiavery well. However, for surgery on the obliquemuscles and when applying posterior fixation su-tures, we insist on general anesthesia to avoidthe pain associated with excessive pulling on themuscle. The same applies to the patient with endo-crine orbitopathy.

Instruments, Sutures,Needles

The complete instrument set that we use in strabis-mus surgery is shown in Figure 26–4. Although


not all of these instruments are routinely used foreach procedure, we like to have the complete setavailable for each operation. For the control ofminor bleeding we use Visi-Sorb AbsorbentSticks.* Unlike Q-Tips, which after each applica-tion leave numerous irritating cotton fibers behind,or Weck sponges, which are too soft for applyingpressure on a capillary bleeding site, we havefound these cellulose sticks especially suitable formuscle surgery.

For all recessions and resections, we use 6-0coated Vicryl (polyglactin 910) suture with an S-14 spatula needle. Vicryl is a synthetic, absorbablesuture that has practically eliminated acute allergicsuture reactions or formation of postoperativegranulomas. However, this suture has some tissuedrag; therefore it is somewhat difficult for theinexperienced surgeon to tie snugly to the sclera.Vicryl (7-0) on a GS-9 needle is used for conjunc-tiva closure.

Some surgeons prefer nonabsorbable suturessuch as silk, Dacron (polyethylene teraphthalatefiber), nylon, or Mersilene for recession or resec-tion operations. However, unless the knot is buriedunder the muscle, as advocated by Reinecke,234

such sutures remain visible through thin conjunc-tiva for many years; for this reason, we havestopped using them.

Attempts have been made to reattach muscle tosclera by means other than suturing and thus toavoid the risks of perforation and intraocular in-fection. Various tissue glues have been experi-mented with and Spierer and coworkers271 showedthat fibrin sealant was effective in reattaching ex-traocular muscles in rabbits, provided a musclerecession was large. With small recessions thecontractile strength of the muscle exceeded theholding power of the glue. Clearly, this researchis still in its exploratory stage and its importancehas also been diminished by the much increasedsafety of muscle surgery and the development ofspatula needles. Unlike curved cutting and re-versed cutting needles, these needles have a flatback, a thin profile, a sharp tip, and a cutting edgeonly at the sides. In our opinion, they are prefera-ble to all other needles for strabismus surgery. Theimproved control of passage of the needle throughthe superficial lamellae of even the thinnest scleraminimizes trauma and the danger of perforation.

*VISITEC, 7575 Commerce Court, Sarasota, FL 34243-3218and Waterloo Road Industrial Estate, Bidford-on-Avon, War-wickshire B504JH, England.

The needle must be passed through the sclera insuch a manner that it remains visible through thescleral lamellae at all times. We prefer the sametype of needle for traction sutures.

Surgical Techniques

Few ophthalmologic operations have so manyvariations as surgery of the extraocular muscles.Methods of exposing muscle, passing or tying thesuture, and measuring the amounts of recession orresection differ with each surgeon. It follows thata specified number of millimeters of muscle reces-sion or resection will have a different effect on adeviation in the hands of one surgeon than inthose of another surgeon. A surgeon’s techniqueis determined largely by training. With growingexperience and exposure to other methods a sur-geon is likely to modify procedures and eventuallydevelop an individualized technique. In the fol-lowing discussion, only those techniques are dis-cussed to which the authors of this book havebecome accustomed, without implying that ourmethods are better than the many others in usebut not described in this book. We reviewed thesurgical techniques of 17 North American strabis-mus surgeons and found vast differences in theirtechnique of reattaching the muscle to thesclera.187 Several texts dealing with extraocularmuscle surgery are available to which the readeris referred for a description of methods other thanthose discussed here.32, 106, 218, 245, 304

We do not believe that strabismus surgery mustbe routinely performed under the operating micro-scope but believe that surgical loupes and optimalillumination, enhanced, if necessary, by a fiberop-tic headlight worn by the surgeon, are indispens-able aids to optimal surgical technique.

Preparation of the Eye

The periorbital skin is scrubbed for 3 minutes withhexachlorophene (pHisoHex) after which the skinand the upper and lower fornices are thoroughlyrinsed with normal saline. The periorbital skin isthen dried with a sterile towel and painted withpovidone-iodine (Betadine). Isenberg and cowork-ers119 advocated rinsing the ocular surfaces with ahalf-strength povidone-iodine solution routinelyfor strabismus surgery after having shown an anti-bacterial effect of this preparation. There is alsosome evidence that this procedure may decrease


the prevalence of bacterial endophthalmitis,266, 267

although additional data based on a randomizedprospective study are lacking to further substanti-ate this claim.

Fixation of the Globe

During general anesthesia the eye may rotate in-conspicuously around its anteroposterior axis. Un-less recognized by the surgeon, this malorientationof the globe may lead to an incision at the wrongplace and even to surgery on the wrong muscle.For orientation and for improved exposure, weprefer fixation sutures that permit rotation andfixation of the globe into any desired positionduring the procedure. These sutures (6-0 Mersi-lene on an S-14 needle) are inserted through theconjunctiva and superficial sclera close to the lim-bus in the 12- and 6-o’clock positions for surgeryon horizontal muscles and in the 9- and 3-o’clockpositions for surgery on vertical rectus muscles.For surgery on the inferior oblique muscle, onlyone suture is inserted close to the limbus in theinferotemporal quadrant. Before inserting the fix-ation sutures, the surgeon must verify the positionof the eye by looking for prominent landmarkssuch as the insertion of the rectus muscles, whichnormally can be identified through overlying con-junctiva and Tenon’s capsule, or the positions ofthe semilunar fold and caruncle.

Conjunctival Incision and Exposureof a Rectus Muscle

Various techniques for exposing the rectus mus-cles have been described, most of which consistof direct or indirect transconjunctival incisionsanterior or posterior to the muscle insertion or inthe fornix.215 Each of these methods has advan-tages and disadvantages, but in our opinion, theyare somewhat less than ideal. An ideal techniqueshould be technically simple and minimally trau-matic, provide quick access to the muscle, andachieve an optimal cosmetic result soon after sur-gery. These criteria are met by the limbal conjunc-tival incision, which probably was used as earlyas von Graefe’s time but was reintroduced byCortes (1962)46 in South America, by Massin andHudelo (1962)155 and de Decker (1967)52 in Eu-rope, and by von Noorden (1968–1969)184, 185 inthe United States. Zugsmith309 had suggested ear-lier (1959) the use of this incision for surgery onthe inferior oblique muscle.

By using this incision, we found that the nor-mal anatomical relationship between Tenon’s cap-sule and conjunctiva remains undisturbed and thatTenon’s capsule is not traumatized. The limbalconjunctival incision not only provides easy, quickaccess to the muscle but causes minimal rednessand prevents adhesions, leading to an optimal cos-metic and functional result. Another advantage ofusing this incision is that conjunctival recessionor adjustable sutures can be performed with easeand that surgical exposure during muscle transpo-sitions is better than through a fornix-based inci-sion.

The various steps of the limbal conjunctivalincision are illustrated in Figure 26–5 in whichexposure of the right medial rectus muscle is usedas an example. The surgeon sits at the right tempo-ral side of the patient’s head and the assistant atthe opposite side. All illustrations used in thischapter to demonstrate surgical techniques showthe eye as viewed by the surgeon.

After insertion of the lid speculum, two 6-0Mersilene sutures are placed with spatula needlesthrough the episclera and the limbus in the 6-and 12-o’clock positions, and the eye is rotatedtemporally to expose the site of the operation(Fig. 26–5A). Conjunctiva and Tenon’s capsule areunited into a single layer close to the limbus. Thusa conjunctival incision in the limbal area providesdirect access to Tenon’s space. The conjoinedlayer is grasped close to the limbus, and a smallradial incision is made through these layers per-pendicular to the limbus down to the sclera (Fig.26–5B). The combined layer of conjunctiva andTenon’s capsule is undermined by spreading theblades of spring-action blunt Wescott scissors(Fig. 26–5C) and is then severed from the limbus(Fig. 26–5D). At this point, slight bleeding fromthe perilimbal capillaries may be encountered butis easily controlled by pressure with absorbentsponges or an application with the wet field cau-tery.

The second radial incision is then made (Fig.26–5E). The radial incisions are 3 to 4 mm inlength, but may be extended 5 mm or more whena large recession or a posterior fixation suture isplanned. The curved tenotomy scissors are theninserted into the upper and lower nasal quadrant,and the blades are spread gently only once toseparate Tenon’s capsule from the episclera (Fig.26–5F and G). Care must be taken not to advancethe scissors directly toward the muscle insertionto avoid injury to muscle fibers, which could cause


FIGURE 26–5. Conjunctival incision, muscle exposure, and wound closure. For explanation, see text.(From von Noorden GK: Extraocular muscles. In Beyer-Machule CK, von Noorden GK, eds: Lids,Orbits, Extraocular Muscles, Vol 1. In Heilmann K, Paton D, eds: Atlas of Ophthalmic Surgery. NewYork, Thieme-Stratton, 1985.)

Illustration continued on following page

bleeding. The conjunctival flap is then retracted,with forceps or a Graefe muscle hook No. 3 anda Jameson muscle hook is then inserted with itstip pointing away from the insertion (Fig. 26–5H).

The muscle is engaged by rotating the hook180� (arrow in Fig. 26–5H) and exposed by

applying traction to the handle of the hook (Fig26–5I). The assistant exposes the muscle and itsinferior and superior fascial connections (falci-form folds of Guerin) by lifting conjunctiva andTenon’s capsule with two Graefe hooks No. 3(Fig. 26–5J). The inferior border of the muscle is


FIGURE 26–5 Continued. For legend, see p. 585.

freed by sharp dissection (Fig. 26–5K), afterwhich the superior border is similarly exposed(Fig. 26–5L) and freed by dissection (not shown).

When one exposes the lateral rectus muscle,especially if this muscle has previously been oper-ated on, it is advisable to pass the tip of the musclehook under the muscle insertion from above toavoid accidental engagement of muscle fibersfrom the inferior oblique muscle.108 Failure to rec-

ognize this potential complication results in post-operative hypertropia or deficiency of vertical ro-tation.176

After completion of the procedure the woundis closed with two 7-0 Vicryl sutures on a GS-9needle passed through the edges of the flap, limbalconjunctiva, and episclera (Fig. 26–5M and N).These sutures should be cut short to avoid irrita-tion. If the perpendicular incisions are larger than



4 or 5 mm, they may be closed with one additionalsuture. While the wound is being closed, it isimportant not to leave a conjunctival ridge nearthe limbus, since this is cosmetically unsatisfac-tory and causes interruption of the tear film thatin turn may produce a corneal delle.

Occasional difficulties may be encountered inidentifying the wound edges, and special caremust be taken not to grasp and suture Tenon’scapsule, which may prolapse spontaneously fromunder the conjunctiva during the operation, espe-cially after the tissue has been excessively manip-ulated. To distinguish between conjunctiva andTenon’s capsule, it is helpful to remember that,unlike conjunctiva, Tenon’s capsule is an avascu-lar structure. For the less experienced surgeon werecommend placement of a small suture knot ateach edge of the conjunctival flap to identify thecorners at the conclusion of the operation.

Recession of a Rectus Muscle

After exposure of the rectus muscle, as shown inthe preceding discussion, the surgeon must deter-mine whether the muscle is completely engagedby passing a second hook repeatedly from aboveand from below or, in the case of the verticalrectus muscle, nasally and temporally under theinsertion. During a recession operation, we alwayscut the check ligaments, although some surgeonsbelieve that this does not enhance the effect ofsurgery.80 During surgery on the superior rectusmuscle, accidental inclusion of the superioroblique tendon on the muscle hook must beavoided. When recessing the inferior rectus mus-cle, one should take special care to dissect the

intermuscular membrane and all fascial attach-ments between the inferior rectus muscle andLockwood’s ligament as far posterior as possibleto prevent postoperative changes in the positionof the lower lid. When isolating the inferior rectusmuscle, one should remember that the nerve sup-ply to the inferior oblique enters this muscle justas it passes the lateral border of the inferior rectusmuscle, 12 mm posterior to the inferior rectusinsertion.

After the muscle has been thus prepared, twosingle-armed sutures are inserted and locked tothe lower and upper edges of the muscle close tothe insertion (Fig. 26–6A–D). As mentioned ear-lier, we prefer a 6-0 coated Vicryl suture withspatula needles for all recession operations. Careis taken to include all anterior ciliary arteries inthe suture lock. Serrefines are clamped to thearmed end and the free end of each suture for lateridentification. The surgeon then applies tension tothe muscle hook and the sutures (Fig. 26–6E)while the muscle tendon is dissected from thesclera using curved Stevens tenotomy scissors(Fig. 26–6F). Bleeding from the capillaries on themuscle stump is controlled by applying pressureor using wet field cautery. While the stump of theinsertion remaining on the sclera is grasped witha forceps, the assistant places one prong of thepreset caliper next to the forceps and indents thesclera with the other end (Fig. 26–6G) to providea mark to identify the site of reinsertion. Keechand coworkers135 pointed out that the insertion sitemay be displaced anteriorly more than 1 mm dur-ing disinsertion of the muscle and while pullingon it with a fixation forceps to stabilize the globeduring determination of the reattachment site. This


FIGURE 26–6. Recession of the right medial rectus muscle. For explanation, see text. (From vonNoorden GK: Extraocular muscles. In Beyer-Machule CK, von Noorden GK, eds: Lids, Orbits, Extraocu-lar Muscles, Vol 1. In Heilmann K, Paton D, eds: Atlas of Ophthalmic Surgery. New York, Thieme-Stratton, 1985.)

factor needs to be considered if the insertion siteis used as a point of reference. The needles arethen inserted through the sclera, entering the tissueat the mark and emerging slightly lateral and par-allel to the limbus (Fig. 26–6H and I). The needleshould be visible at all times while passingthrough superficial scleral lamellae, and deep pas-sage, especially perforation, must be avoided. Thesutures are then tied and cut, and the new insertionis carefully inspected before closing the wound(Fig. 26–6J).

Some authors prefer to hang back the muscleroutinely on a suture loop from the original inser-tion rather than suture it to the sclera.64, 85, 167,

238, 236 This technique is used by us only in patientswith very thin scleras, those with scleral exoplantsafter retinal surgery, or when there are mechanicalrestrictions that prevent adequate exposure of the

scleral reattachment site. In most other situationswe feel more secure knowing that the muscle isexactly where we put it with sutures. The possibil-ity exists that a suture-suspended muscle maymove toward its old insertion once the eye isreturned to primary position at the end of theoperation. Interestingly, the histologic examinationof loop-recessed extraocular muscles revealed thatthe sutures eventually become replaced by a pseu-dotendon that resembles real tendon.64

Resection of a Rectus Muscle

Resection of a rectus muscle is illustrated usingthe right lateral rectus as an example. The surgeonfaces the left side of the patient’s head; the assis-tant is on the opposite side.

After being exposed and placed on a muscle


FIGURE 26–6 Continued. For legend, see p. 588.Illustration continued on following page

hook (see Fig. 26–5), the rectus muscle is freedas far as necessary to apply the resection clamp.Fascial structures are left intact as much as possi-ble since their presence may add materially to theeffect of the operation. A Jameson resection clampis then placed on the muscle with its smooth sidetoward the underside of the muscle belly (Fig.26–7A). The clamp is placed so that its posterioredge corresponds with the amount of muscle thatis to be shortened, as determined with a caliper(Fig. 26–7B). One should not pull excessively onthe muscle when making this measurement, sincethe amount of resection is calculated by theamount of the unstretched muscle.

A common error of inexperienced surgeonsduring this step of the operation may result inresecting more of the muscle than intended. Thisoccurs when the tendon is plicated as the musclehook pulls the eye toward the surgeon (Fig. 26–7C). Since this folded part is not included in the

caliper measurement, an additional 2 to 3 mm ofmuscle may thus be unintentionally resected.

After the clamp has been applied and locked,the muscle is severed from the sclera with curvedtenotomy scissors at its point of insertion and anyfootplates or other connections of the tendon tothe sclera are removed at that time (Fig. 26–7D).Wet field cautery is used to control bleeding ofthe muscle stump. Two double-armed 6-0 coatedVicryl sutures are then placed through the stump,one needle of each suture being placed close tothe center of the insertion and the other throughthe corresponding end (Fig. 26–7E–G).

The sutures are then carried through the mus-cle, which is lifted by the clamp, and the needlesare placed through the underside of the belly asclosely as possible to the posterior edge of theblade of the clamp (Fig. 26–7H). The central su-tures are placed close to the middle of the musclebelly and the outer sutures at the corresponding


FIGURE 26–6 Continued. For legend, seep. 588.

edge of the muscle. As the needle emerges on theother side of the clamp, the assistant grasps it withan angled utility forceps (Fig. 26–7I). Each pairof sutures is placed in a serrefine, which is re-moved only when the suture is being used again,to prevent confusion between the four suture ends(Fig. 26–7J). The assistant then takes hold of themuscle clamp and pulls the muscle forward to-ward its old insertion while the surgeon ties eachsuture with a triple knot (Fig. 26–7K). The clampis loosened slightly, then refastened to grasp themuscle at its end. The muscle is crushed with anangled hemostat (Fig. 26–7L). The muscle seg-ment anterior to the sutures is then removed withscissors (Fig. 26–7M). The muscle is inspected(Fig. 26–7N) and any bleeding at this time iscontrolled with wet field cautery, after which thewound is closed at the limbus (Fig. 26–7O).

The spring-back balance test introduced byJampolsky125 may prevent overcorrections from ex-cessive resection of a muscle and is used by usroutinely during surgery. After completion of theresection and before closure of the conjunctiva the

globe is grasped at the limbus with two forceps inthe same manner as during the forced duction test.The eye is rocked back and forth several times inthe desired plane and then quickly released. Thefinal position of the globe and the velocity of thespring-back are noted. If, for instance, the lateralrectus muscle has been resected too much, the eyewill come to rest in a position of abduction. Thesurgeon is then well advised to recess the pre-viously resected muscle to avoid an overcorrectionthat will certainly occur if the test result is ignored.

If additional strengthening is desirable, themuscle may be advanced 1 or 2 mm toward thelimbus, in which case the muscle should be sev-ered from the sclera as closely as possible toavoid adhesion between the old insertion and theunderside of the muscle belly. The benefits derivedfrom an advancement procedure are based onlengthening the arc of contact between the muscleand globe, thus increasing the rotational force ofthe contracting muscle. This effect will be neutral-ized if the muscle becomes reattached to its oldinsertion.


FIGURE 26–7. Resection of the right lateral rectus muscle. For explanation, see text. (Modified fromvon Noorden GK: Extraocular muscles. In Beyer-Machule CK, von Noorden GK, eds: Lids, Orbits,Extraocular Muscles, Vol 1. In Heilmann K, Paton D, eds: Atlas of Ophthalmic Surgery. New York,Thieme-Stratton, 1985.)


Adjustable Sutures

Interest has been revived in reattaching a recessedor resected muscle to the sclera in such a mannerthat the effect of surgery can be augmented ordecreased during the postoperative period by pull-ing on or loosening the sutures, which are thenretied under topical anesthesia. This technique was

described as early as 1885 in the United States228

and at one time was in vogue in Europe.101 It hasbeen modified and again made popular in our timeby Jampolsky.127 This approach is based on theassumption that the position of the eye at the endof surgery, hours after surgery or on the firstpostoperative day, when such adjustments can bemade, reflects its position after the postoperative



tissue reaction, photophobia, and ocular discom-fort have subsided. This assumption remains un-proven. Except for large undercorrections andovercorrections, which tend to persist throughoutthe postoperative phase, we have not found theimmediate postoperative position of the globe tobe of much help in assessing the final result ofsurgery. In fact, in one study the operative result6 weeks after surgery differed from that 24 hoursafter surgery in 28 (40%) of 70 patients.207 Inanother study, major and significant changes in

ocular alignment occurred between the first dayand 6 weeks after surgery.34 Although the directionand magnitude of such changes were unpredict-able, most patients showed recurrences in the di-rection of the preoperative deviation.34

Postoperative suture adjustments in children areoften difficult, and sedation or even general anes-thesia may be required. For these reasons, we donot use adjustable sutures in children. However,we have found them to be of value in patients inwhom multiple previous operations or restrictive


FIGURE 26–7 Continued. For legend, seep. 591.

forms of strabismus (scarring, contracture) haveadded a substantial factor of unpredictability tothe outcome of the operation. Another indicationfor their use exists in paralytic strabismus with agood potential for restoration of single binocularvision. Wisnicki and coworkers299 reported thatthe use of adjustable sutures reduced the frequencyof reoperations in their patients.

The adjustable suture technique in recession ofthe right medial rectus muscle is shown as anexample. A double-armed 6-0 coated Vicryl sutureis passed and tied through the center of the tendon

and then passed and locked through its upper andlower edges (Fig. 26–8A–C). The muscle has beensevered from the sclera, and the sutures have beeninserted through the scleral muscle stump (Fig.26–8D). The muscle has been allowed to recede adesired amount. Moving the sutures back and forthseveral times (arrows) widens the scleral tunnelcreated by the sutures and facilitates suture adjust-ment the following day.

The sutures are tied, first with a single knot,then with a bowknot (Fig. 26–8E). The conjunc-tiva has been closed with two interrupted 7-0


FIGURE 26–8. Adjustable suture. For explanation, see text. (Modified from von Noorden GK: Extraoc-ular muscles. In Beyer-Machule CK, von Noorden GK, eds: Lids, Orbits, Extraocular Muscles, Vol 1.In Heilmann K, Paton D, eds: Atlas of Ophthalmic Surgery. New York, Thieme-Stratton, 1985.)

Vicryl stitches (Fig. 26–8F), using a bare scleralclosure technique. The end of the suture that willopen the bowknot is left long for later identifica-tion. A traction suture (5-0 Mersilene) may beinserted through the superficial sclera between thelimbus and the old tendon insertion to facilitateexposure by rotating the globe during suture ad-justment (not shown).

If the eye is in a satisfactory position postoper-atively and no adjustment is necessary, the suture

bow must be opened and a third knot added tosecure the knot. The bowknot is removed (notshown in this figure) by cutting the loop andpulling out the now disconnected suture fragmentthat has been previously identified by leaving itsend long. The remaining double knot is tightenedand a third double knot is added before the re-maining two sutures are cut. The conjunctiva isleft in its recessed position.

For suture adjustment on the first postoperative


FIGURE 26–8 Continued. For legend, see p. 595.Illustration continued on following page

day, the knot is opened by pulling on the long endof the suture after the conjunctiva has been locallyanesthetized (Fig. 26–8G). To allow the muscle toslide posteriorly, the globe is fixed with forceps(or traction suture) while the patient looks in thedirection of the field of action of the recessedmuscle (Fig. 26–8H). To move the muscle towardthe original insertion, it is pulled forward by

means of the sutures while the patient is asked tolook in the direction of the pull (Fig. 26–8I).After adjustment is completed, the sutures arepermanently tied with a triple surgical knot (Fig.26–8J) and in a few days the knot will be coveredby conjunctiva (Fig. 26–8K).

When there is no conjunctival scarring or con-tracture of conjunctiva or Tenon’s capsule, this



technique may be modified by making the initialincision directly anterior to the muscle insertion.The wound is then closed with two interruptedstitches (6-0 Vicryl [polyglactin 910]), leaving acentral gap through which the suture can be ad-justed and tied (Fig. 26–8L). The postoperativecosmetic appearance, especially when operatingon the horizontal recti, is better than after barescleral closure. When the adjustment is made,advancing a muscle is easier to accomplish thanadditional recession since a muscle rapidly ad-heres to its new insertion. It is easier to break themuscle from the sclera by actively pulling it for-ward than by allowing it to slide back. Whenusing adjustable sutures for resections, therefore,it is recommended that 3 mm be added to thedesired amount of resection and that the musclebe recessed 3 mm at the same time so that both asurgical undereffect and overeffect can be cor-rected.

Pulling on the muscle usually is accompaniedby a dull ache despite topical anesthesia, and thepatient should be advised of this beforehand.

Not all adults are good candidates for sutureadjustment. We have found that anxious patientsor those who cooperate poorly during tonometryor the forced duction test in the office may beuncooperative during suture adjustment and evenrequire sedation, which defeats the very purposeof this procedure. Patients in whom bradycardiaor other cardiac dysrhythmias develop on tractionof any extraocular muscle during surgery shouldbe excluded from this type of procedure sincesimilar problems may occur during suture adjust-ment.118, 293

No convincing data are available to show thatstrabismus surgery using adjustable sutures is su-perior to conventional methods. However, there isno question that the possibility of correcting or atleast decreasing a large overcorrection or under-correction on the first postoperative day is reassur-ing both to the surgeon and the patient.

Marginal Myotomy of a RectusMuscle

Of the many techniques used to lengthen a muscle,the marginal myotomy of von Blaskovics andKreiker17 has emerged as the most effective. Thereason for the less beneficial results of the othermethods, such as the tenotomy after O’Connor200

or Verhoeff,289 is that unless the central fiber bun-dles of the muscle are sectioned, only insignificantamounts of lengthening of the insertion are ob-tained.107, 140 Hemostasis is obtained by brieflycrushing the tissue to be cut with a mosquitohemostat (Fig. 26–9A), after which the myotomyis performed, with at least 70% of the width ofthe muscle being sectioned from above and below(Fig. 26–9B). If available, we prefer to do themyectomy by using battery-driven thermocautery(not shown), which prevents hemorrhage from themuscle section. After completion of the myecto-mies, the muscle has been lengthened (Fig. 26–9C). It is important to first make an incision distalto the insertion, followed by a second incisionthrough the muscle or tendon proximal to theinsertion. Distortion of the muscle or tendon oc-curs when the proximal incision is first made,which causes difficulties in gauging the length


FIGURE 26–9. Marginal myotomy of the right medial rectus muscle. For explanation, see text.

of the second incision. Reoperations followingmarginal myotomies are difficult and should beavoided if at all possible.

Myectomy of the Inferior ObliqueMuscle

We shall discuss only the technique of myectomyin the lower temporal quadrant, a procedure thatin our hands has given the best results. The opera-tion is illustrated using the right inferior obliquemuscle as an example. Positions of the surgeonand assistant are shown in Figure 26–10.

The eye is elevated in adduction with a tractionsuture passed through conjunctiva and episcleranear the limbus in the inferotemporal quadrant(Fig. 26–11A). A two-step incision is then made,first through the conjunctiva and then throughTenon’s capsule close to the fornix but on thebulbar side of the conjunctiva to stay clear of themore heavily vascularized tissue in the fornix (Fig.26–11B). Bleeding from conjunctival capillaries,which obscures the operative field and thus inter-feres with direct visualization of the inferioroblique muscle, can be avoided by opening con-junctiva and Tenon’s capsule with battery-driventhermocautery (not shown).

The scissors blades are placed in the incisionand spread, exposing the sclera (Fig. 26–11C).Care must be taken to avoid injuring the infero-temporal vortex vein, usually located in this re-gion, with the tip of the hook. The wound edgesare then retracted with a Desmarres lid speculumto expose the muscle. The muscle can be seen asa salmon-pink, flat structure lying in a pocket ofTenon’s capsule (Fig. 26–11D). Great emphasis

is placed on adequate exposure, because manysurgeons make the mistake of searching blindlyfor the muscle with a sharp instrument and therebyrun the risk of causing considerable tissue damageor injury to the muscle.

After being exposed, the muscle is engagedunder direct visualization on a short Graefe hook(Fig. 26–11E). Closed scissors blades are thenplaced under the muscle, and Tenon’s capsule isperforated by spreading the scissors blades (Fig.26–11F). Muscle hooks are placed under the mus-cle, which is then stretched (Fig. 26–11G). Themuscle is clamped with two hemostats approxi-mately 8 mm apart (Fig. 26–11H) and the myec-tomy is performed by excising the muscle segmentbetween the clamps. One should not cut the mus-

FIGURE 26–10. Position of surgeon and assistant formyectomy of the right inferior oblique muscle. (From vonNoorden GK: Extraocular muscles. In Beyer-Machule CK,von Noorden GK, eds: Lids, Orbits, Extraocular Muscles,Vol 1. In Heilmann K, Paton D, eds: Atlas of OphthalmicSurgery. New York, Thieme-Stratton, 1985.)


FIGURE 26–11. Myectomy of the right inferior oblique muscle. For explanation, see text. (From vonNoorden GK: Extraocular muscles. In Beyer-Machule CK, von Noorden GK, eds: Lids, Orbits, Extraocu-lar Muscles, Vol 1. In Heilmann K, Paton D, eds: Atlas of Ophthalmic Surgery. New York, Thieme-Stratton, 1985.)

cle flush with the clamp but should leave a stumpfor subsequent thorough cauterization (Fig. 26–11I) to prevent postoperative hemorrhage or reat-tachment of the muscle segment(s) to the scleraor Tenon’s capsule.

The effect of a myectomy can be severely lim-

ited if the surgeon leaves even a few strands ofintact muscle. It is absolutely essential at this pointto ensure that all the muscle fibers have been cut,and the sectioned muscle should be examined todetermine whether the muscle sheath is intact pos-teriorly. The posterior aspect of the muscle may



have slipped off the Graefe hook during its expo-sure, and the surgeon must search for any missedmuscle fibers that must be cut or for an anomalousposterior insertion of the muscle, which is notuncommon.26 Cadaver studies have shown thatmultiple insertions occurred in 17% and a bifidinsertion in 8% of 100 eyes examined.51

The conjunctiva may be closed with one or twointerrupted 7-0 Vicryl sutures (Fig. 26–11J), orclosure may be omitted, because sufficient coapta-tion of the wound edges occurs without suture themoment the eye is released from the traction su-ture. The eye is now grasped with forceps closeto the limbus and rotated several times to spreadthe muscle stumps as far from each other as possi-ble (not shown).

Inadvertent sectioning of the inferior rectusmuscle rather than the inferior oblique muscle isa rare complication that can be avoided by fixationof the globe in an adducted and elevated position

and by exposing the muscle under direct visualiza-tion. Also, the flat inferior rectus muscle differsconsiderably in appearance from the more ovalinferior oblique muscle, the fibers of which runperpendicular to those of the inferior rectus mus-cle. Before proceeding with the myectomy of theinferior oblique muscle, the less experienced sur-geon is advised to identify the inferior rectus mus-cle by placing a muscle hook under its insertion.

Recession of the Inferior ObliqueMuscle

For a recession of the right inferior oblique musclethe surgeon and assistant are positioned as shownin Figure 26–10. The eye is elevated and main-tained in adduction by means of a traction suturepassed through conjunctiva and superficial sclerallamellae near the limbus in the inferotemporalquadrant (Fig. 26–12A) The conjunctiva is opened


FIGURE 26–12. Recession of the right inferior oblique muscle. For explanation, see text.

as for a myectomy in the inferior temporal quad-rant so as to expose the inferior oblique muscle,which is engaged with a hook under direct visual-ization (Fig. 26–12B). Care is taken to check withtwo muscle hooks that all the fibers, particularlythe posterior ones, are engaged and that a triangleof bare sclera is visible between the hooks (Fig.26–12C). As mentioned earlier, anomalies of theinsertion of this muscle are not uncommon andmust be searched for since recessing only part ofa multiple insertion may account for a persistentmuscle overaction. A double-armed suture of Vi-

cryl 6-0 is passed through the muscle as close aspossible to its insertion and is locked and tied atthe edges of the muscle (Fig. 26–12D). Theamount of recession is measured from the positionof the suture with a caliper (Fig. 26–12E) and anindentation is made into the sclera with the caliperto mark the point of reinsertion. The amount ofrecession ranges from 5 to 10 mm, depending onthe degree of overaction. The muscle is detachedfrom the sclera with scissors (Fig. 26–12F) andreinserted to the sclera at the predetermined site(Fig. 26–12G).



Tenectomy of the Superior ObliqueMuscle

Improved techniques for exposure and isolation ofthe superior oblique tendon under direct visualiza-tion, as advocated by Parks and Helveston,219 havepractically eliminated all complications previouslyincurred with tenectomy of the superior obliquemuscle, such as injury to the medial horn of thelevator muscle with subsequent ptosis, injury tothe superior rectus muscle, or perforation of theorbital septum with prolapse of orbital fat. Theoperation is illustrated using tenectomy of theright superior oblique as an example and the posi-tions of the surgeon and assistant are shown in

Figure 26–13. We prefer to perform this procedurewhile standing.

Figure 26–14A shows exposure of the superioroblique tendon. The incision is made through theconjunctiva and Tenon’s capsule between the me-dial and superior rectus muscles, 4 to 5 mm behindthe limbus. As during opening of the conjunctivaand Tenon’s capsule for a myectomy of the infe-rior oblique, thermocautery may be used to gainaccess to the sclera (not shown). The wound isgently spread with the tips of blunt tenotomyscissors (Fig. 26–14B).

One muscle hook engages the superior rectusmuscle, and the eye is turned downward and out-ward by applying traction on the muscle hook,


FIGURE 26–13. Position of surgeon and assistant fortenectomy of the right superior oblique muscle. (Fromvon Noorden GK: Extraocular muscles. In Beyer-MachuleCK, von Noorden GK, eds: Lids, Orbits, Extraocular Mus-cles, Vol 1. In Heilmann K, Paton D, eds: Atlas of Ophthal-mic Surgery. New York, Thieme-Stratton, 1985.)

held by the assistant (Fig. 26–14C). The upperedge of the wound is retracted upward. Ratherthan using a forceps or a third muscle hook, asadvocated by Parks and Helveston,219 we use asmall Desmarres lid retractor, which providesatraumatic exposure (Fig. 26–14D). The tendon ofthe superior oblique can be seen as a glisteningwhite band lying in a pocket of Tenon’s capsule.Visualization of the tendon is facilitated if thesurgeon wears a headlight. A small Graefe hookis used to engage the tendon and pull it forward(Fig. 26–14E). Scissors blades are then spread toisolate the tendon (Fig. 26–14F and G).

The tissue surrounding the tendon is incised toidentify the tendon proper, the glistening appear-ance of which reminds us of mother-of-pearl (Fig.26–14H). This step of the operation is alwaysrecommended for the less experienced surgeonsince strands of Tenon’s capsule may be mistakenfor the tendon. If an isolated tenotomy is to beperformed, the tendon is pulled from the sheath atthis point and cut (not shown). To remove a pieceof tendon, including its sheath, the tendon isspread between two hemostats and clamped (Fig.26–14I), after which a section is removed withscissors (Fig. 26–14J and K). The tendon has agritty consistency that is different from other tis-sue and should be easily recognized by the sur-geon when cutting through this structure. Thewound is now closed with one stitch of 7-0 Vicryl(Fig. 26–14L), after which the muscle hook isremoved.

Recession of the Superior ObliqueMuscle

Recession of the superior oblique muscle is shownfor the right eye. The positions of surgeon andassistant are depicted in Figure 26–13. The supe-rior oblique tendon has been exposed in the uppertemporal quadrant, as for a tuck. In Figure 26–15Athe conjunctiva has been opened, close to thetemporal border of the superior rectus, and baresclera and the superior oblique tendon insertionare visible. A hook, inserted under the superiorrectus muscle insertion and held by an assistant,has depressed the globe toward the 6-o’clock posi-tion. A small Desmarres retractor provides goodexposure of the operating field above. Two single-armed sutures have been inserted and locked tothe anterior and posterior part of the tendon inser-tion. After the tendon has been detached withscissors (Fig. 26–15B) the sclera is marked with acaliper, nasal to the superior rectus muscle and asequidistant from the limbus as the original inser-tion. The tendon is resutured to the sclera at thenew insertion (Fig. 26–15C).

Tucking of the Superior ObliqueMuscle

Tucking of the superior oblique muscle is illus-trated using a tuck of the right superior obliquetendon as an example. The surgeon sits at theright side of the patient’s head, the assistant at theopposite side (Fig. 26–16). The right eye has beenrotated downward with two traction sutures in-serted near the limbus through conjunctiva andepisclera.

An incision is made through conjunctiva andTenon’s capsule with scissors (Fig. 26–17A) orthermocautery (not shown). Stevens tenotomyscissors have been introduced into the wound, andthe blades are spread only slightly to avoid injuryto the temporal border of the superior rectus mus-cle (Fig. 26–17B). A muscle hook has been placedunder the superior rectus insertion (Fig. 26–17C).By applying traction to the hook the eye is rotatedfurther downward. The posterior wound edge ispulled upward with a small Desmarres retractor.The temporal border of the superior rectus is liftedwith a Graefe muscle hook No. 1 and the superioroblique tendon is exposed with a sweeping motionof a second Graefe hook No. 1 (Fig. 26–17D). ABurch tendon tucker or its von Noorden modifica-tion192 has been introduced beneath the superior


FIGURE 26–14. Tenectomy of the right superior oblique muscle. For explanation, see pp. 602 and603. (From von Noorden GK: Extraocular muscles. In Beyer-Machule CK, von Noorden GK, eds: Lids,Orbits, Extraocular Muscles, Vol 1. In Heilmann K, Paton D, eds: Atlas of Ophthalmic Surgery. NewYork, Thieme-Stratton, 1985.)



FIGURE 26–14. Continued. For legend, see p. 604.


FIGURE 26–15. Recession of the rightsuperior oblique muscle.

oblique tendon. The folded tendon is drawn intothe tucker by turning the screw at the tip of theinstrument (screw not shown) (Fig. 26–17E). Afterachieving the desired amount of tucking, which isdetermined by tightness or slacking of the tendon(usually between 6 and 12 mm), the cuff of theinstrument (large arrow) is brought forward, thusclosing the blades of the instrument (Fig. 26–17F).The tuck is fastened beneath the instrument withtwo 5-0 nonabsorbable sutures, after which thetucker is removed (Fig. 26–17G and H). We donot fasten the tucked portion of the tendon to the

sclera as this maneuver may inadvertently pull thetendon anteriorly and thus decrease the verticaleffect of the operation and also contribute to post-operative limitation of elevation (pseudo-Brownsyndrome). Forced ductions are now performed todetermine the degree of restriction when elevatingthe adducted eye. Mild elastic restriction is desir-able and should result in a good effect from theoperation. Severe restriction necessitates undoingthe tuck and tucking a lesser portion of the tendon.The wound is then closed with one interruptedstitch of 7-0 Vicryl.

FIGURE 26–16. Position of surgeon and assistant for tuckingof the right superior oblique tendon. (From von Noorden GK:Extraocular muscles. In Beyer-Machule CK, von Noorden GK,eds: Lids, Orbits, Extraocular Muscles, Vol 1. In Heilmann K,Paton D, eds: Atlas of Ophthalmic Surgery. New York, Thieme-Stratton, 1985.)

Anterior and Lateral Displacement ofthe Superior Oblique Tendon forExcyclotropia (Harada-Ito Procedure)

Jackson121 suggested recession and lateral dis-placement of the superior rectus tendon to counter-

FIGURE 26–17. Tucking of the right superior oblique tendon. For explanation, see text, p. 603. (Fromvon Noorden GK: Extraocular muscles. In Beyer-Machule CK, von Noorden GK, eds: Lids, Orbits,Extraocular Muscles, Vol 1. In Heilmann K, Paton D, eds: Atlas of Ophthalmic Surgery. New York,Thieme-Stratton, 1985.)

607

act excyclotropia in patients with paresis of thesuperior oblique muscle. We have found the opera-tion described by Harada and Ito100 to be effective.This procedure involves anterior and lateral dis-placement of the anterior portion of the superioroblique, thereby increasing the incycloduction ef-


608


FIGURE 26–18. Harada-Ito operation (right superior oblique tendon). For explanation, see text. (Fromvon Noorden GK: Extraocular muscles. In Beyer-Machule CK, von Noorden GK, eds: Lids, Orbits,Extraocular Muscles, Vol 1. In Heilmann K, Paton D, eds: Atlas of Ophthalmic Surgery. New York,Thieme-Stratton, 1985.)

fect between 9� and 15� in downward gaze.143, 191

The operation is illustrated using the right superioroblique tendon as an example.

The lateral aspect of the superior oblique ten-don is exposed as for the tucking procedure. Anonabsorbable 5-0 single-armed suture is passedon a spatula needle through the anterior portion ofthe tendon, 3 mm nasal to its insertion (Fig. 26–18A). The suture is tied firmly with a triple knot.The needle is then passed through superficial scle-ral lamellae, 3 mm temporally and anterior tothe insertion. By tying the suture over its scleralfixation, the anterior portion of the tendon ispulled laterally and anteriorly (Fig. 26–18B). Theconjunctiva is closed with one or two interrupted7-0 absorbable sutures, and the muscle hook isremoved.

Fells70 has modified this operation by splittingthe tendon at its insertion and transposing theanterior half anteriorly and laterally, and Metz andLerner163 advocated the use of an adjustable suturefor this procedure (see also Ohmi and cowork-ers204).

Using the procedure described by Harada andIto we have noted that the effect of the operationtends to diminish in the course of time191. Thesame has been observed by other authors.11, 175, 286

Thus, if adjustable sutures are used at all, a slightovercorrection on the first postoperative dayshould not be reversed by a suture adjustment.Indeed, such initial overeffects are common anddo not unfavorably influence the final outcome.194

In reviewing our results with the Harada-Ito proce-

dure in nine patients we found that the reductionof the excyclotropia in primary position rangedfrom 8� to 25�, and in downward gaze, from 12�to 30�.194

Posterior Fixation Suture

As an example of posterior fixation suture, poste-rior fixation of the right superior rectus muscle isused to explain the procedure. A limbal conjuncti-val incision is made to expose the muscle, andthe two incisions perpendicular to the limbus areextended approximately 6 to 8 mm posteriorly.The superior rectus has been secured with twosingle-armed 6-0 Vicryl sutures (see Fig. 26–6A–D), severed from the globe (see Fig. 26–6E andF), and is held in a Jameson muscle clamp (Fig.26–19A).

For maximal depression of the globe, two addi-tional traction sutures may be inserted through thesclera at the site of the old insertion (Fig. 26–19B).A Schepens speculum or a similarly shaped retrac-tor (malleable brain retractor, Charles microretinalretractor) is used to expose the sclera retroequator-ially while marking the sites of the posterior fixa-tion with calipers (Fig. 26–19C). A curved Scottruler (not shown) should be used for markingposterior fixation sates exceeding 9 mm since thecaliper, measuring the chord rather than the arc,becomes inaccurate beyond this distance.38 Forlonger arc measurements the amount of inaccuracydepends on axial length. The Scott ruler can intro-duce significant measuring errors when measuring


FIGURE 26–19. Posterior fixation of the right superior rectus muscle. For explanation, see text.(From von Noorden GK: Extraocular muscles. In Beyer-Machule CK, von Noorden GK, eds: Lids,Orbits, Extraocular Muscles, Vol 1. In Heilmann K, Paton D, eds: Atlas of Ophthalmic Surgery. NewYork, Thieme-Stratton, 1985.)


arc length as small as 12 mm in small eyes and14 mm in large eyes.

The sutures (5-0 Dacron with a D-1 8-mmneedle) are placed 14 mm posterior to the nasaland temporal edges of the superior rectus (Fig.

26–19D). The surgeon must avoid injury to thesuperior vortex veins (not shown) with the retrac-tor. Both sutures are now in place (Fig. 26–19E)and the speculum has been removed (Fig. 26–19F). The muscle is brought downward (Fig. 26–


FIGURE 26–19 Continued

19F and G) and reattached to the sclera 4 mmbehind its original insertion (Fig. 26–19H). Thetemporal suture is passed through the muscle fromunderneath, incorporating one third of the muscle,while the assistant lifts the edge of the muscle andpulls it laterally (arrow) with a Graefe hook No.1 (Fig. 26–19H). Both sutures, fixating the lateralone third of the muscles, have been tied and cut

(Fig. 26–19I). Firm fixation of the muscle is testedwith a muscle hook (Fig. 26–19J), after which thewound is closed in the usual fashion (see Fig.26–5N). When the incisions, are gaping, two inter-rupted sutures are used on each side for closure.When there is no deviation in primary position,the operation is performed without recession asshown in Figure 26–19K and L.


TABLE 26–1. Recommended Distances of PosteriorFixation

Distance BehindInsertion

Muscle (mm)

Medial rectus 12–15Lateral rectus 13–16Superior rectus 11–16Inferior rectus 11–12

From von Noorden GK: Posterior fixation suture in strabismussurgery. In Symposium on Strabismus: Transactions of the NewOrleans Academy of Ophthalmology. St Louis, Mosby-YearBook, 1978.

The recommended minimal and maximal dis-tances of posterior fixation are shown in Table26–1.

Muscle Transposition Procedures

HORIZONTAL AND VERTICAL RECTUS MUS-

CLES IN THE TREATMENT OF A AND V PAT-

TERNS. The indications and effects of raising andlowering the insertion of the horizontal rectusmuscle or nasal or temporal transposition of thevertical rectus muscles are discussed in Chapter19. Exposure and surgical technique do not differfrom the performance of a recession or resectionof the rectus muscles; however, the limbal incisionshould be extended toward the direction in whichone plans to move the insertion to gain betterexposure, and the muscle should be reinsertedparallel to the limbus. The effect may be modifiedby shifting the insertion between one-half and onefull muscle width.

VERTICAL RECTUS MUSCLES IN THE TREAT-

MENT OF HORIZONTAL STRABISMUS. Tempo-

FIGURE 26–20. The cyclotorsional effect of hori-zontal transposition of the vertical rectus muscles.For explanation, see text. RSR, right superior rec-tus; LSR, left superior rectus; RIR, right inferiorrectus; LIR, left inferior rectus; nas., nasalward;temp., templeward.

ral transposition of the vertical rectus muscles foresotropia and nasal transposition for exotro-pia were also recommended by Nawratzki andBenezra181 for horizontal deviations, when maxi-mal surgery on the horizontal muscles fails tocompletely align the eyes or if the surgeon isreluctant, for some reason, to operate on the felloweye. Provided there are no mechanical restrictions,we can confirm the effectiveness of this procedure.However, we recommend only partial transposi-tion of the tendon if previous surgery has beenperformed on the horizontal recti. Great care mustbe taken to leave viable anterior ciliary vessels inthe part of the muscle segment that remainsattached to the globe to prevent anterior segmentischemia. In children a full tendon-width transpo-sition may be performed regardless of whether thehorizontal rectus muscles have been previouslyoperated on.

VERTICAL RECTUS MUSCLES IN THE TREAT-

MENT OF CYCLODEVIATIONS. Horizontal trans-position of one or both vertical rectus musclescorrects cyclotropia (see p. 391) or may be usedto induce a cyclodeviation to treat a compensatoryhead tilt to one shoulder in patients with a nystag-mus null zone in a tertiary gaze position (see p.524). Figure 26–20 shows the direction in whichthe vertical rectus muscles must be transposed tocause incycloduction or excycloduction of eacheye. We perform a full tendon transposition andreattach the nasal and temporal border of eachmuscle in accordance with their preoperativelymeasured distance from the limbus. Figure 26–21shows the direction of the transpositions to causeincycloduction of the right eye. This operationwill correct (or induce) a cycylodeviation of 11�(range, 8� to 12�) when performed on both verticalrectus muscles.


FIGURE 26–21. Position of reattached vertical rectusmuscle tendons to produce incycloduction of the righteye.

HORIZONTAL RECTUS MUSCLES IN THE

TREATMENT OF CYCLODEVIATIONS. This pro-cedure, introduced by de Decker,53 may be usedfor the indications outlined in the preceding para-graph as an alternative to horizontal transpositionof the vertical rectus muscles in adults who havehad previous surgery on the horizontal rectus mus-cles.

HORIZONTAL RECTUS MUSCLES IN THE

TREATMENT OF VERTICAL STRABISMUS. Ver-tical transposition of the horizontal rectus musclesin the treatment of comitant vertical strabismuswas introduced by Foster and Pemberton,75 wholowered or raised the lateral rectus muscle to treathypertropia or hypotropia. Alvaro3 advocated low-ering or raising the insertions of both horizontalrectus muscles and combining this procedure withrecession or resection to achieve simultaneous cor-rection of vertical and horizontal deviations. Thistechnique has found acceptance among many oph-thalmic surgeons,136, 160, 200, 202, 214 and we found iteffective in reducing the hyperdeviation from 8�

to 13� when the muscles are transposed by onemuscle width. To lower an eye, the insertions arelowered; to raise an eye, they are raised.

HORIZONTAL OR VERTICAL RECTUS MUSCLES

IN PARALYTIC STRABISMUS. Resection of a par-alyzed muscle does little to improve its functionunless the paralysis is incomplete. Some tempo-rary mechanical advantage may be gained by com-bining resection of a completely paralyzed musclewith recession of its antagonist; however, rotationof the globe into the field of action of the para-lyzed muscle cannot be restored and the eye tendsto return to its preoperative position. However,

muscle transposition procedures may restore somedegree of motility to the eye in the field of gazeof the paralyzed muscle.

Jackson121 and Hummelsheim115 are both cred-ited with being the originators of muscle transposi-tion for paralytic strabismus, and most techniquessubsequently used111, 200, 130, 137 are derived from theprocedure of Hummelsheim, in which the lateralpart of the superior and inferior rectus muscles istransposed to the lateral rectus insertion for abdu-cens paralysis. The numerous modifications of thisprocedure, all of which are based on the sameprinciple, were reviewed by Helveston104 andMetz.161, 162

The question has been debated whether inner-vational adjustment takes place so that the trans-posed muscle can carry out coordinated move-ments in different directions from its original fieldof action19, 20 or whether the effect of muscletranspositions is merely mechanical.287 We favorthe view that muscle transpositions have only amechanical effect, which was substantiated byEMG studies of Metz and Scott.164

Before considering a muscle transposition, thesurgeon must determine that ocular motility is notimpeded by mechanical factors by using theforced duction test (see p. 423). Such restrictionsmust be removed first, usually by maximal reces-sion of the contractured antagonist of the pareticmuscle and, if necessary, by conjunctival reces-sion. We state categorically that a muscle transpo-sition should never be performed unless passivemovement of the eye is unrestricted in the pareticfield of gaze.

Many of the muscle transposition proceduresin use, especially those performed in combinationwith resection of the paretic muscle and recessionof its antagonist, have the disadvantage that theintegrity of the insertion of more than two rectusmuscles is disturbed. Although many adult pa-tients tolerate well such interference with theblood supply from the anterior ciliary arteries, wehave seen in consultation several patients in whomischemic anterior segment necrosis (see p. 620)occurred after surgery on three or four rectus mus-cles in one session. The severity of this complica-tion is such that transposition of the entire tendonshould be considered only if at least one rectusmuscle insertion is intact and has not been pre-viously operated on. Otherwise, partial transposi-tion should be considered.

For double elevator or double depressor paral-ysis, we transpose the insertion of the horizontal


rectus muscle to that of the superior rectus orinferior rectus muscle, as suggested by Knapp.137

The operation illustrating transpositions of thehorizontal recti in a patient with double elevatorparalysis of the right eye is shown in Figure 26–22. The horizontal recti have been exposed witha limbal incision between the 4- and 8-o’clockpositions and secured with two single-armed su-

FIGURE 26–22. Transposition of horizontal rectus muscles to insertion of the right superior rectusaccording to Knapp. For explanation, see text. (From von Noorden GK: Extraocular muscles. In Beyer-Machule CK, von Noorden GK, eds: Lids, Orbits, Extraocular Muscles, Vol 1. In Heilmann K, PatonD, eds: Atlas of Ophthalmic Surgery. New York, Thieme-Stratton, 1985.)

tures (6-0 Vicryl), after which the muscles aresevered from the globe by sharp dissection (Fig.26–22A). The lateral rectus is transposed to thetemporal edge of the superior rectus muscle (Fig.26–22B). Both horizontal recti are shown in theirfinal position (Fig. 26–22C), after which the con-junctiva is closed near the limbus with two stitchesat the 4- and 8-o’clock positions (not shown). The


FIGURE 26–23. Muscle union according to Jensen. For explanation, see p. 616. (From von NoordenGK: Extraocular muscles. In Beyer-Machule CK, von Noorden GK, eds: Lids, Orbits, ExtraocularMuscles, Vol 1. In Heilmann K, Paton D, eds: Atlas of Ophthalmic Surgery. New York, Thieme-Stratton, 1985.)

improved ocular motility in the vertical field ofgaze to be obtained with this method is mostsatisfactory, and horizontal gaze is restricted little,if any.

For cranial nerve VI paralysis, we use a full

tendon-width transposition of the vertical rectusmuscles to the insertion of the lateral rectus mus-cle or the procedure described by Jensen,130 com-bined with a 6- or 7-mm recession of the medialrectus muscle. To enhance the effect of lateral


transposition of the vertical rectus muscles, Fos-ter75 suggested fixation of one fourth of each mus-cle to the sclera 16 mm posterior to the limbuswith a nonabsorbable 5-0 Dacron suture. The ra-tionale for this approach is based on recent find-ings with MRI that showed very little retroequa-torial lateral displacement of a transposed verticalrectus muscle.166 This stability of the posteriormuscle path is thought to be the effect of musculo-orbital tissue connections (muscle pulleys).

The Jensen procedure is illustrated in Figure26–23 using the right eye as an example. Thesurgeon has to move around to work on bothvertical recti and the lateral rectus and for bettermobility should stand during this operation. Theright eye is rotated medially by means of tractionsutures inserted through episclera near the limbusat the 1- and 5-o’clock positions and a partialperitomy has been performed (Fig. 26–23A).When combining the operation with a recessionof the medial rectus, a total peritomy is requiredto gain access to all rectus muscles. The superior,lateral, and inferior recti have been exposed, andthe tendon of the lateral rectus is split in its centerwith a muscle hook (Fig. 26–23B). The tendonsof the lateral, inferior, and superior recti have alsobeen split (Fig. 26–23C). At least one branch ofthe anterior ciliary vessel should remain in thenasal segment of each of the vertical recti thatare not incorporated in the muscle union.187 Thetemporal half of the superior and the superior halfof the lateral rectus muscles have been looselytied with a nonabsorbable suture (5-0 Mersilene)over the equator, and a similar muscle union hasbeen completed between the temporal half of theinferior and the inferior half of the lateral rectus

FIGURE 26–24. Improvement of ocular deviation in primary position and levoversion after Jensenprocedure and medial rectus recession for a left sixth cranial nerve paralysis. A, Preoperatively. B,Postoperatively.

(Fig. 26–23D). The conjunctiva is closed with twostitches at the limbus (Fig. 26–23E).

Our results with respect to moving the pareticeye from a position of extreme adduction intoprimary position and restoring abduction from 5�to 10� have been satisfactory in most instances(Fig. 26–24) (see also Frueh and Henderson81). Anovercorrection during the immediate postoperativeperiod frequently occurs but this is usually a tran-sient phenomenon that disappears spontaneouslyand therefore need not be of concern to the sur-geon. Selezinka and coworkers257 reported an aver-age reduction of 40� esotropia in primary positionand an average postoperative abduction of 18� in16 eyes with sixth nerve paralysis after medialrectus recession combined with a rectus muscleunion according to Jensen.

Jensen developed this operation to protect thepatient against anterior segment ischemia but, un-fortunately, this protection is not 100%. The seniorauthor, after having encountered anterior segmentischemia following the Jensen procedure com-bined with recession of the ipsilateral rectus mus-cle in an elderly lady,188 no longer uses this opera-tion in older persons. Similar results can beobtained and complications avoided by doing a‘‘partial Knapp’’ instead, that is, by transposingonly the temporal halves of the superior and infe-rior rectus muscles to the insertion of the lateralrectus muscle, while taking very special care toleave at least one intact anterior ciliary artery ineach of the nasal muscle stumps. This is onesituation in which the operating microscope maybecome indispensable during eye muscle surgery.

SUPERIOR OBLIQUE TENDON IN CRANIAL

NERVE III PARALYSIS. Transposition of the supe-


rior oblique tendon was suggested first by Drans-art,60 who sutured the resected tendon to the upperpart of the lateral rectus insertion in the case oftraumatic disinsertion of the tendon. Jackson,120

Wiener,296 and Peter221 described a technique bywhich the tendon is removed from the trochlea,resected, and reattached to the sclera near theinsertion of the medial rectus muscle in cases ofoculomotor paralysis. The effect is mechanical;the resected tendon pulls the eye from abductiontoward the primary position. The superior obliquetendon is exposed under direct visualization andengaged with a muscle hook, as described earlierin this chapter. A small closed mosquito hemostatis then slid along the tendon until its tip entersthe pulley of the trochlea. Opening the hemostatfractures the pulley, and the tendon can be disen-gaged. The tendon is shortened at least 10 or 12mm and then sutured to the sclera near the upperborder of the medial rectus muscle. This operationis combined with extensive recession (10 to 12mm) of the lateral rectus muscle and maximalresection of the medial rectus muscle.

Some ophthalmologists have observed that ad-duction is improved after this procedure,47, 106 butin our experience this has not always been thecase. Our approach to a complete oculomotor pa-ralysis is outlined on page 448.

Recession of Conjunctiva andTenon’s Capsule

The elasticity of the conjunctiva and Tenon’s cap-sule may be impaired severely if an eye has beendeviated in one position for a long time or if scarshave formed from previous operations. This factormust be considered in the etiology of mechani-cally restricted ocular motility. In such patients,forced closure of the conjunctiva after weakeningthe action of a muscle will counteract the effectof muscle surgery. Considering for how long con-junctival recession and baring of the sclera havebeen used in the surgical treatment of pterygium,21

it is surprising that this technique was seldomused in strabismus surgery until it was popularizedby Cole and Cole40 in 1962. These authors showedthat a bare scleral closure after strabismus surgeryis effective in eliminating mechanical restrictionsof conjunctiva and Tenon’s capsule, that it is un-complicated, and that reepithelialization occurs ina short time. For obvious reasons the limbal con-junctival approach is especially suitable in musclesurgery if a conjunctival recession is planned at

FIGURE 26–25. Bare sclera closure. For explanation, seetext. (From von Noorden GK: Extraocular muscles. InBeyer-Machule CK, Noorden GK von, eds: Lids Orbits,Extraocular Muscles, Vol 1. In Heilmann K, Paton D, eds:Atlas of Ophthalmic Surgery. New York, Thieme-Stratton,1985, p 218.)

the end of the operation. The conjunctiva is re-cessed to a point slightly anterior to the newmuscle insertion and fastened to the sclera withinterrupted 7-0 Vicryl sutures to prevent prolapseof Tenon’s capsule (Fig. 26–25) and to act as abarrier against re-formation of scar tissue. Excessconjunctiva should be excised to achieve a neatclosure without leaving an unsightly mass of ele-vated tissue. We do not routinely use conjunctivalrecessions but limit their use (1) to patients inwhom one or both eyes have remained in a posi-tion of extreme adduction, abduction, or depres-sion for a long time and in whom conjunctivaltightness must be respected, (2) to those withextensive conjunctival scarring, and (3) to patientswhose previously negative traction test after surgi-cal reattachment of a muscle becomes positiveafter conjunctival closure.

Traction Sutures

If adhesion formation that might counteract theeffect of the operation is anticipated, traction su-tures may be used to hold the globe in an overcor-rected position for several days after surgery. Thistechnique is as old as the beginning of musclesurgery, was used as early as 1848 by Dieffen-bach,58 was mentioned by von Graefe92 and byGruening,97 and was revived by Martinez,154 Vil-


laseca,292 and Callahan.33 Traction sutures are indi-cated after surgery for large angle unilateral devia-tions in adults in whom prior surgery wasunsuccessful, leaving massive scar formation. Forinstance, in the treatment of a large unilateralesodeviation, two 5-0 Mersilene sutures on a spat-ula needle are placed through episclera near thelimbus at the 12- and 6-o’clock positions. Theneedles are then cut off and each suture is re-threaded through a skin needle. This needle ispassed through the lateral conjunctival fornix toemerge through the skin over the orbital rim. Bytying the sutures over a rubber peg, one can rotatethe eye into extreme abduction. The sutures areleft in place for 7 to 10 days. Care must be takento insert the sutures so that they do not overrideand erode the cornea. Some surgeons pass thesutures through the insertions of the rectus musclefor better anchoring, but in our experience thisprovides less of a fulcrum to rotate the eye.

Use of Plastic Materials

In the prevention of adhesions and preservation ofmuscle function after isolation from scar tissueduring reoperations, plastic sheaths138 or sleeves61, 62

were once popular and said to enhance the man-agement of persistent strabismus. We no longeruse these materials and have relied instead onreducing trauma to the muscle by using painstak-ingly gentle surgical manipulation of the tissuesand reducing adhesions by meticulously cleaningthe sclera.

Complications

Surgical Complications

Hemorrhages during surgery may result from cut-ting a conjunctival vessel or from accidentallycutting into the muscle during exposure. Some-times the scleral muscle stump hemorrhages afterthe muscle has been disinserted. An intraconjunc-tival or intramuscular hematoma occasionally maydevelop. Control of bleeding is essential beforecontinuing with the operation, since organizationof the clot and subsequent scarring will inevitablyresult and unfavorably influence the surgical re-sult. Cauterized tissue promotes scar formation;therefore, electrocautery should be used sparinglyand only if a bleeding vessel can be directly iden-tified. We have found wet field cautery especially

useful in muscle surgery, since it keeps tissuecoagulation to a minimum. Most hemorrhages,particularly from a capillary bed, respond well tobrief pressure with a cellulose sponge that may besoaked with a drop or two of 1:10,000 epineph-rine; however, permission must be obtained fromthe anesthesiologist to use this drug. The conjunc-tival incision must never be closed until all hemor-rhages have been controlled. Most hemorrhagescan be prevented by delicate handling of the tissueand by including the marginal vessels of the extra-ocular muscles in the sutures.

One of the most distressing complications dur-ing strabismus surgery is the loss of a musclebecause of inadvertent transection during surgeryor as a result of direct trauma, breaking of thesutures, slippage from the muscle clamp, sponta-neous disintegration while exerting pull on themuscle hook (‘‘snapped muscle’’),180 or slippageand contracture of the muscle belly within themuscle capsule, which remains attached to thesclera.180, 223 The last complication usually involvesthe medial rectus muscle and occurs during thepostoperative phase. It must be suspected when alarge overcorrection with incomitance suddenlydevelops after initial alignment. Muscle slippageis caused by superficial suture placement that doesnot incorporate the entire thickness of the tendon.Neural imaging is indispensable in locating theslipped muscle prior to attempts to retrieve andreattach it.

When the muscle snaps or is lost during theoperation, the surgeon, above all, must remaincalm. Under bright illumination (headlight or mi-croscope, if necessary), with the help of additionalassistants and optimal exposure with malleableretractors, the area in which the muscle loss issuspected should be gently explored by hand-over-hand grasping of Tenon’s capsule, to which poste-rior fibers of the muscle are usually attached.The direction of exploration should occur in thedirection of the muscle, that is, in the case of themedial rectus muscle, along the medial orbitalwall, rather than toward the posterior pole wherethe muscle will rarely be found and injury to theoptic nerve is a risk.152 Irrigation of the operativefield with balanced salt solution may cause thepink color of the muscle to contrast with thewhitish color of Tenon’s capsule and thus helpidentification of even a few remaining musclefibers. These should be immediately secured witha suture. Rather than making later identificationof the muscle difficult or even impossible by un-


necessarily traumatizing the tissues, the inexperi-enced surgeon is well advised to call for consulta-tion or to close the wound and refer the patientimmediately to an expert surgeon for reexplora-tion. Neural imaging, especially computed tomog-raphy (CT) or MRI, may then be helpful in identi-fying the location of the muscle and in decidingwhether further exploration should be attemptedor, in the case of a lost medial rectus muscleretracted too far posteriorly, whether a nasal trans-position of the vertical rectus muscles should beperformed at this time. In our experience, a musclecan be reattached and will function normally evenmany months after it was lost during surgery. Ifthe muscle was irretrievably lost, Brown recom-mended resecting and suturing Tenon’s capsule tothe muscle stump,25 but we consider a muscletransposition to be the more effective procedure.

Inadvertent perforation of choroid or retinamay occur when the needle is passed too deeplythrough the slecera. This complication probably ismore common than generally realized37, 90, 132, 147,

160, 178, 260 but its occurrence has markedly declinedsince cutting needles have been replaced by spat-ula needles. The prevalence of chorioretinal perfo-ration after conventional muscle surgery has re-cently been reported to range from 0.4%183 to1.5%15 on the basis of individual studies of largepatient groups. A survey conducted by Simon andcoworkers260 among285 members of the AmericanAssociation of Pediatric Ophthalmology and Stra-bismus showed a prevalence of scleral perforation,as defined to include known retinal damage, inonly 0.13% of 553,565 cases. An unusually highprevalence of 15.5% of chorioretinal scarring wasreported to occur after posterior fixation sutures atthe site of the scleral anchorage.2 This figure con-trasts with a prevalence of only 7% after thisoperation at Moorfields Eye Hospital.151

One must consider the possibility that not allpigmented lesions at muscle reinsertion sites arecaused by perforation but may be the result oflocal tissue reaction to the suture material. In anycase, retinal detachment endophthalmitis9, 90, 102, 247

and phthisis bulbi5 have been reported as infre-quent but extremely serious complications of inad-vertent perforation. Thus whenever perforation oc-curs during surgery, the retina should be examinedimmediately and the patient placed on systemicantibiotics and referred to a retinal specialist onthe following day. Most retinologists will opt forobservation without treatment. Such patientsshould be monitored closely during the immediate

postoperative phase with slit-lamp and fundus ex-aminations for signs of intraocular inflammationand infection. We routinely check postoperativepatients with a retinoscope for a bright fundus re-flex.

A scleral wound made during dissection of themuscle insertion from the globe should be se-curely sutured and surrounded with diathermy orcryotherapy. The retina should be examined at thetime of surgery and at close intervals during thepostoperative period. Preventive measures includeavoiding excessive pull on the muscle hook, whichmay force the sclera between the scissors bladeswhen the muscle is being dissected from the globe,and exercising extreme care in patients with thinsclera, such as high myopes.

Transient mydriasis of the eye operated on mayoccur after detachment of a rectus or oblique mus-cle and is probably caused by release of neuro-transmitters from tissue damage.123 It disappearssoon after surgery and is without clinical signifi-cance.

Complications of Anesthesia

Complications arising from anesthesia duringmuscle surgery are, fortunately, extremely rare,even though anesthesia is never entirely withoutdanger. However minimal the risk may be, thepossibility that severe and at times life-threateningsituations can suddenly develop during the opera-tion or the recovery period should never be ig-nored. The ophthalmic surgeon must keep abreastof modern methods of cardiac resuscitation andbe able to assist the anesthesiologist in the man-agement of cardiac arrest. The incidence of mor-tality during general anesthesia for strabismus sur-gery is not known exactly. Gartner and Billet82

conducted a survey among 557 North Americanophthalmologists and reported a total of 72 deathsduring the 10-year period between 1946 and 1956.Over half of these deaths occurred in patientsunder 7 years of age. A similar survey conductedin Germany by Knobloch and Lorenz,139 whopolled 324 ophthalmologists, revealed 60 deaths,56 of which occurred during general anesthesia.These authors estimated that the number of opera-tions on which this figure is based was approxi-mately 300,000. J. Cooper and coworkers44 esti-mated the mortality rate to be 1.1 per 10,000cases, which indicates that more people die as aresult of tooth extraction (17.42 per 10,000) thanas a result of strabismus surgery.


In addition to cardiac arrest and asphyxia fromother causes, hereditary or idiopathic malignanthyperthermia is cited as another life-threateningcomplication of general anesthesia.16, 24, 265 A care-ful history and constant monitoring of the rectaltemperature during strabismus surgery have be-come routine in most operating rooms so thatthis problem may be detected early during theprocedure. For details regarding the pathophysiol-ogy, diagnosis, and treatment of this fulminanthypermetabolic crisis, the reader is referred to theexcellent reviews by Gronert95 and by Marmor,153

as well as the special bulletin issued by the Ameri-can Society of Anesthesiologists.282 We have en-countered malignant hyperthermia on only fouroccasions and not once since we banned the useof succinylcholine in our operating room duringstrabismus surgery. In each instance, the alert pe-diatric anesthesiologist noted trismus during theinduction phase and anesthesia was stopped beforethe surgery began. Creatinine phosphokinase(CPK) levels were abnormally high in these chil-dren. They were eventually readmitted, treatedpreoperatively and before induction with intrave-nous dantrolene, and tolerated anesthesia withoutfurther complications.

When taking the patient’s history, the surgeonmust always search for information with respectto unusual reactions to an anesthetic agent bymembers of the patient’s family, since there areseveral other genetic conditions, such as hepaticporphyria and suxamethonium sensitivity, thatcause severe complications during and after gen-eral anesthesia.89 A less harmful complication isbradycardia caused by vagal stimulation, whichresults from pulling on the muscles, especially themedial rectus muscle. This oculocardiac reflex isa transient phenomenon and the surgeon mustimmediately stop any operative manipulation ofthe eye. The cardiac rhythm is usually restoredafter the pull on the muscle is relaxed, but intrave-nous injection of atropine is usually given by theanesthesiologist at this point. Injection of atropineis recommended prophylactically in all patientswho are to undergo muscle surgery, and an addi-tional dose is administered when the reflex iselicited during surgery.

Milot and coworkers168 applied a standardizedtraction force to all extraocular muscles duringsurgery and reported no difference in the sensitiv-ity of a particular muscle to stretching. However,they noted that quick traction was more likely toelicit the oculocardiac reflex than slow, progres-

sive traction. As mentioned above, patients inwhom the oculocardiac reflex can be elicited dur-ing surgery become poor candidates for adjustablesutures. There is consensus among anesthesiolo-gists that electrocardiographic monitoring is im-portant during all types of eye surgery to detectpotentially dangerous cardiac rhythm distur-bances.158

Postoperative Complications

Postoperative vomiting used to be a most unpleas-ant sequela of muscle surgery but is rarely a prob-lem now since it can be controlled effectively withdroperidol (Inapsine) administered intravenously(0.075 mg/kg) during induction of anesthesia.67

Infections following strabismus surgery are rarebut endophthalmitis is the most dreaded complica-tion after strabismus surgery and nearly alwaysresults in phthisis bulbi and blindness. Knoblochand Lorenz139 reported 87 cases following approxi-mately 300,000 strabismus operations performedin Germany. A higher incidence (1:30,000) wasreported by Ing117 in his survey of 63 North Amer-ican strabismologists. From these reports the roleof inadvertent scleral perforations in the etiologyof endophthalmitis is not clear. Most studies90, 102,

260, 287 indicate that intraocular infections followingmuscle surgery can be related directly to scleralperforation. Such complications can be preventedby good surgical technique and by routine use ofspatula needles during muscle surgery.

Orbital cellulitis is rarely mentioned in theliterature. Only eight cases have been reported98,

112, 186, 199, 294, 297 but it might be safely assumed thatthis severe and potentially life-threatening compli-cation occurs far more frequently than indicatedin the literature. Ing117 reported an incidence oforbital cellulitis and subconjunctival abscess afterstrabismus surgery of 1 in 1900 cases. In the twopatients reported by us, the infection developedon the second and third postoperative days, re-spectively, accompanied by the characteristic clin-ical signs of orbital infection, that is, proptosis,swelling of the eyelids, chemosis, and restrictionof ocular motility. Both patients responded well tomassive intravenous and topical antibiotic treat-ment and recovered completely. CT is indicatedto exclude abscesses that may require draining.Since most surgeons discharge patients who havehad extraocular muscle surgery either on the dayof surgery or on the first postoperative day, it


is important to recognize that this complicationmay occur.

A most unusual complication of muscle surgeryis a localized suture abscess, which one mustassume to be caused by contaminated suture mate-rial. We have seen this complication only onceand, as one would perhaps expect, in the child ofa colleague and close associate. Rapid localizedswelling and erythema developed over the inser-tion of the medial rectus muscle 7 days after aresection operation. The abscess was incised andpus drained from the wound; the organism waslater identified as Staphylococcus aureus. Healingwas uncomplicated, but subsequent formation ofadhesions in the area of the abscess caused me-chanical restriction of ocular motility, and reopera-tion became necessary.

Suture reactions used to be common but havebecome virtually extinct since the introduction ofsynthetic absorbable sutures. They occurred eitheras an acute allergic reaction between 24 hours and7 days after surgery or as a delayed foreign bodyreaction 6 to 8 weeks later. During the acute stagethe patient complained of ocular discomfort anditching and marked chemosis; hyperemia of theconjunctiva and swelling of the lids also may bepresent. The reaction could be so fulminating thatretractors were necessary to open the lids.

Granulomas have become equally rare. Theyoccur from 2 to 4 weeks after surgery and repre-sent a nonallergic foreign body reaction to thesuture material, cotton fibers, glove powder, or aneyelash buried in the wound. Characteristically, alocalized, elevated, slightly hyperemic mass willappear over the muscle insertion and at times willform a pedicle type of attachment to the sclera.Treatment consists of topically applied corticoste-roid drops, and excision of the granuloma occa-sionally may become necessary.

Anterior segment ischemia is a more seriouscomplication of muscle surgery, caused by disin-sertion of three or four rectus muscles with theinevitable disruption of blood supply to the ante-rior segment from the anterior ciliary arteries.Several cases are on record in which the patientsdeveloped anterior segment ischemia after surgeryon just two opposing rectus muscles.66, 232, 248, 263 Asurvey conducted among the membership of theAmerican Association of Pediatric Ophthalmologyand Strabismus (1984) showed an estimated inci-dence of less than 1 case for each 13,000 proce-dures.78 Within 24 hours after surgery, microcysticepithelial edema and marked thickening of the

cornea may develop. Prominent folds occur inDescemet’s membrane, and nonpigmented kera-titic precipitates and a mild cellular aqueous hu-mor reaction are usually present. Segmental irisatrophy,280 a fixed and distorted pupil, and cataractformation are late sequelae of this complication.Treatment consists of intensive systemic and topi-cal administration of corticosteroids, and one pa-tient was successfully treated with hyperbaric oxy-gen.263 However, there is no evidence that visualoutcome or the speed of resolution is influencedby such treatment.250 Severe functional impairmentof the eye and even phthisis bulbi have beenreported.84, 104

Apparently the tolerance to a reduction ofblood supply to the anterior segment is higher inchildren than in adults84 but exceptions do occur.Anterior segment ischemia occurred in a childwith retinopathy of prematurity after surgery onthe horizontal recti66 and in a healthy 10-year-oldafter a Jensen procedure combined with recessionof the ipsilateral medial rectus muscle.18 Anteriorsegment ischemia has been observed in older pa-tients in whom the Hummelsheim procedure orone of its modifications was combined with sur-gery on one or both horizontal rectus muscles.69,

74, 84, 250, 279 It has been described in a leukemicpatient after surgery on the two horizontal rectusmuscles122 and in a 66-year-old woman after theJensen procedure combined with a medial rectusrecession.188 Saunders and Sandall249 reported an-terior segment ischemia following full tendontransposition of the superior and inferior rectusmuscles 9 and 20 years after ipsilateral horizontalrectus muscle surgery. Although fluorescent irisangiography appeared to be a promising methodto determine when collateral circulation developedafter muscle surgery,103, 210, 211, 245 the ‘‘safe’’ inter-val after which the second procedure can beplanned is unknown and subject to wide individualvariations. The probable mechanism of redistribu-tion of blood flow to the anterior segment afterdisinserting the muscles is via the long posteriorciliary arteries. Routine preoperative angiogramsare not recommended. As a general rule, we ad-vise waiting at least 6 months in adult patientsafter surgery on both horizontal rectus musclesbefore operating on the vertical recti.

Several methods have been reported for preser-vation of the anterior ciliary vessels during musclesurgery.79, 141, 159, 246 These range from microdissec-tion of the vessels from the muscle under theoperating microscope or loupes to a modified


tucking operation during which the muscle withits vessels is plicated rather than detached fromthe sclera and resected. Contrary to what one mayexpect, the vessels in the tucked muscle have beenreported to remain patent postoperatively, at leastin monkeys.306 It is not certain whether the anteriorciliary arteries continue to function after thesemanipulations in humans. These dissection proce-dures are time-consuming and technically difficult,especially in the age group at risk for anteriorsegment ischemia. Moreover, it has been reportedthat this complication can occur despite the use ofblood vessel–sparing surgical techniques.174

Fishman and coworkers72 observed in cynomol-gus monkeys that a fornix conjunctival incisionmay provide partial protection against anteriorsegment ischemia by preserving the perilimbalcirculation. Whether the same holds true for hu-mans remains to be established. For additionaldiscussion and literature references on anteriorsegment ischemia, the reader is referred to a recentreview article.250

A harmless and rare complication is an amputa-tion neuroma that may develop at the site of theold insertion after tenotomy of a muscle as manyas 4 to 8 years after muscle surgery.300, 301

Conjunctival cysts develop when small sectionsof conjunctival epithelium become buried in thewound during closure. The cyst is filled with clearfluid and can be evacuated with a needle punctureunder local anesthesia. If the cyst recurs, excisionbecomes necessary.

Corneal dellen (plural of the German: Delle, asmall depression) are caused by interruption ofthe corneal tear film and local dehydration of thecornea. This benign complication occurs in thepostoperative phase, especially when the limbalincision is used, and must be distinguished frommarginal corneal ulcers. Dellen usually respondwell to a firm bandage applied to the eye for 24to 48 hours. They can be prevented by smoothclosure of the limbal wound and resection of ex-cess conjunctiva to prevent tissue elevation nearthe limbus. Scharwey and coworkers251 reported adecreased prevalence of corneal dellen if plicationof a muscle is used rather than a resection.

A scleral delle after strabismus surgery con-sisted of a dark, translucent scleral patch thatdisappeared after hydration and reappeared on de-hydration and was managed by covering the baresclera with a conjunctival flap.258

A more serious complication involving thesclera is necrotizing scleritis.201 It occurs infre-

quently after strabismus surgery and seems to af-fect mostly patients with autoimmune vasculiticsystemic disease.133, 156, 201 We have observed itonly once, 1 month after strabismus surgery in a60-year-old woman without detectable autoim-mune disease.96 Inflammation was controlled withtopical and systemic corticosteroids and ibuprofen,and good visual acuity was preserved. Interest-ingly, the patient developed a transient myopia ofthe involved eye which had not been previouslydescribed in connection with necrotizing scleritis.Since there was no axial elongation of the eyeon ultrasonography we presume that the anteriorsegment inflammation produced a transient in-crease in the refractive index of the lens.

Changes in the refractive error (mostly astig-matism) have been reported after surgery on theextraocular muscles55, 59, 227, 232, 264, 283 and arethought to be caused by the effects of a temporaryimbalance of muscle forces on the corneal curva-ture.285 One study reported no changes in the cor-neal topography after routine strabismus surgery227

but others have described such changes99, 148, 251

Nearly all anomalies of corneal topography returnto normal after 3 months, but in rare cases aninduced astigmatism may persist.252 The practicalsignificance of these findings is that refractionand, if necessary, a change of glasses should bedelayed until 3 to 4 months after surgery on therectus muscles.

Diplopia often occurs when a patient with com-itant heterotropia undergoes extraocular musclesurgery and the position of the deviated eye ischanged so that the fixated object may no longerfall into the area of the suppression scotoma. Pro-vided there is any vision at all in the eye operatedon, such a patient will have postoperative diplopialasting from a few minutes to a day, a week, or alifetime. How long it persists depends on the abil-ity of the patient to suppress or to ignore thesecond image. Since this ability decreases withage, constant diplopia is more common in adults.Although young children as a rule respond readilyto the new position of the eye with newly formedsuppression, a surprising number actually see dou-ble immediately after strabismus surgery. Unlikeadults, however, children are rarely distressed bydiplopia.

Persistent postoperative diplopia is rare, proba-bly because most patients remain slightly under-corrected after strabismus surgery, and the area ofsuppression extends from the retinal periphery tothe fovea in most forms of horizontal strabismus


and some forms of vertical strabismus. Neverthe-less, the danger of persistent, distressing, postop-erative diplopia must be pointed out to all adultswho desire correction of the deviation. It is thenup to the patient to assume the risk. To assess thisrisk preoperatively and to give the patient a chanceto experience diplopia, we fully or nearly fullycorrect the deviation with prisms placed in a trialframe or fitover frame in front of the glasses. Evenif diplopia can be elicited in this way, this doesnot prove that it will be present after surgery;however, the possibility exists, and the patient atleast has been shown what double vision means.

The attitude of a patient with insufferable post-operative diplopia depends on his or her personal-ity. A stolid person will adjust and in time maylearn to disregard the second image, though it maynot actually be suppressed. More often, the patientknows that the second image should not be there,continually looks for it, and becomes increasinglydistressed and hampered in his or her activities.Insufferable postoperative diplopia occurs notonly in patients with normal visual acuity in thedeviated eye but also occasionally in patients witha deeply amblyopic eye that has been operated on.The second image is then dim, of course, but maycause considerable annoyance to the patient.

Problems arise when treating persistent postop-erative diplopia, especially if the eyes are nearlyaligned and the images are close together. If thissituation can be corrected with prisms, they maybe prescribed, or an additional operation may beperformed. Some form of occlusion therapy is afinal resort when prisms fail or the deviation istoo small for reoperation to be considered. Patientswho underwent surgery for cosmetic reasons in thefirst place usually decline the use of a conspicuousoccluding device. Occluder contact lenses with apainted iris and pupil are acceptable to some.

Overcorrections

Overcorrections happen in the hands of all sur-geons, even the most experienced. They may oc-cur in the immediate postoperative phase ormonths or even years after surgery. Overcorrec-tions may be accompanied by gross incomitanceand inability to move the eye in the field of actionof a weakened muscle and may occur in patientsin whom the action of the muscle operated onappears perfectly normal.

Marked overcorrection can be attributed to ex-

cessive weakening of the action of a muscle orexcessive strengthening of its antagonist. Shouldone note on the day after surgery that a previouslyesotropic eye is exotropic and that the patientcannot adduct that eye even to the midline, partialor complete disinsertion of the medial rectus mus-cle must be suspected. Immediate exploration isthen indicated, since with the passage of time,location of a disinserted and retracted muscle be-comes increasingly difficult. In all other situations,it is advisable to wait at least 6 weeks or longerbefore considering reoperation. In planning sur-gery for overcorrection, one should use the forcedduction test to determine whether the overcorrec-tion is caused by excessive recession or an exces-sive resection. The test will be negative if exces-sive recession has been done. If the muscle hasbeen excessively resected, restriction will be notedon attempts to move the eye in the direction oppo-site the field of action of the resected muscle, inwhich case the resected muscle should be re-cessed.

Cooper42 suggested that ‘‘undoing what wasdone’’ is not always the best way to overcomeovercorrections. He suggested that the surgicaldecision be based on the result of the examination,as in other cases of strabismus, and not on thefact that the patient had prior surgery. Thus apatient who has undergone bimedial recession andis left with a divergence excess type of exodevia-tion is a much better candidate for recession ofboth lateral rectus muscles than for advancementof the previously recessed medial rectus muscles.With the exception of overcorrections caused byobvious mechanical obstacles, we have adhered towhat has become known among North Americanstrabismologists as ‘‘Cooper’s law’’ and find thatovercorrections no longer present the problemsthey once did. The reader is referred to Chapters16 and 17 for a discussion of the clinical manage-ment of overcorrected esodeviations and exodevi-ations.

Postoperative Care

Length of Hospitalization andPostoperative Checkups

The length of hospitalization for strabismus sur-gery in recent years has been drastically reducedin most medical centers of this hemisphere. Thelength of hospital stay is now determined primar-


ily by the time it takes for the effect of generalanesthesia to dissipate rather than by concern forthe success of the operation. Most patients will beable to leave the hospital in the afternoon if sur-gery is performed in the morning. For nearly 40years we have performed muscle surgery on anoutpatient basis without a single untoward inci-dent. Laboratory and physical examinations arecompleted on the day before admission. The pa-tient reports directly to the outpatient surgical suiteon the morning of surgery and is discharged fromthe recovery room on the same day.

It is important to guard against postoperativecomplications and all patients are examined 24hours after surgery. We look for large, unexpectedovercorrections and external or intraocular infec-tions. The brightness of the retinoscopic light re-flex is noted and in older children or adults bio-microscopy is performed. Endophthalmitis mayoccur after an initial normal examination and notuntil 3 to 4 days after surgery.233 Therefore theparents are instructed to return with the childimmediately or, when from out of town, to thelocal ophthalmologist in case of increasing rednessof the eye(s), swelling of the eyelids, lethargy, orfever. Adult patients are alerted to watch for dim-ming of vision in the eye operated on. One weekafter surgery we again reexamine our patients or,in the case of out-of-towners, have the examina-tion performed by the local ophthalmologist. Thefinal postoperative evaluation, including a com-plete motility analysis, is done 6 weeks after sur-gery, at which time the new position of the af-fected eye usually is stable.

Dressing

In some foreign clinics, it is still customary tobandage both eyes for several days even thoughmuscle surgery was performed on only one eye.We are strongly opposed to binocular dressings,since they not only have no effect on the outcomeof the operation but also are most distressing tothe patient, especially a young child. Even withthe best of care, every surgical hospital admissionis emotionally upsetting to the patient, and a bin-ocular dressing contributes further to the feelingof isolation and distress. After routine procedures,we do not even apply a dressing to the eye oreyes operated on, and it is our clinical impressionthat there is less redness, edema, and irritationthan when the eye is patched. However, aftercomplicated reoperations, we apply a mild pres-

sure dressing to the eye operated on for 24 hoursto control postoperative edema. The eye is alsopatched when adjustable sutures are used to avoidinadvertent pulling on the sutures.

Medication

Most North American strabismus surgeons preferto treat the eye operated on with an ointmentcontaining corticosteroids and antibiotics for sev-eral days after surgery187 (see also Chipont andHermosa36). No controlled studies are available tosupport the rationale for such therapy, but fromclinical experience it appears to some that there isless secretion from the wound and more rapidwhitening of the eye if steroids are used for afew days. It is quite possible that the mechanicallubricating effect of the ointment rather than itspharmacologic action may account for this effect.

Corticosteroid-induced glaucoma has been re-ported in an adult patient who noted a suddendecrease of vision 3 days after strabismus sur-gery.35 Infants and young children are unlikely toreport such changes in visual acuity, yet markedintraocular pressure increases after topical cortico-steroids are known to occur in this age group.203

Routine strabismus surgery does not affect theblood-aqueous barrier134 and in view of the forego-ing it appears increasingly doubtful whether post-operative corticosteroids should be prescribed atall.

No ointment is used when adjustable suturesare employed. Medication for postoperative painis rarely required, since most patients experienceonly a mild foreign body sensation and somesoreness on moving the affected eye after musclesurgery.

Whether a postoperative course of oral antibiot-ics is indicated is highly debatable. Consideringthe current litigious climate in the United States,it is perhaps not surprising that many surgeonshave switched over in recent years from no medi-cation to treating their patients with oral antibiot-ics.218 According to a survey conducted by Ing117

among North American strabismologists, there isno evidence that either preoperative or postopera-tive topical or oral antibiotics prevent cellulitis orendophthalmitis after muscle surgery.

REFERENCES

1. Adelstein FE, Cuppers C: Probleme der operativenSchielbehandlung. Ber Dtsch Ophthalmol Ges 69:580,1969.


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