abstracts Edited by C. William Silllcoe, M.J).

British Journal of Physiological Optics

Tucker and Rabie (BrJ Physiol Optics 34:12, 1980) investigated the ability of some pseudophakic patients to read both distant and near without a reading addi­tion. One possible explanation lies in the fact that the pupil is often fairly small which would make the depth-of-focus relatively large and might extend con­siderably the range of clear vision. If the patient is slightly myopic, typically about 1 diopter, and is therefore relatively overcorrected for distance and undercorrected for near, this depth-.of-focus might allow him to see both distant and near without addi­tional correction. This is most likely to occur if the near fixation distance is on the order of 40 - 50 cm rather than 24 - 35 cm. Other possibly significant fac­tors could be any lens shift or a forward shift of the nodal points inherent in the pseudophakic condition.

Bulletin de la Societe BeIge d'Ophtalmologie

Fram.;ois and Verbraeken (Bull Soc Belge Ophtalmol 187:59, 1980) reported a series of 1,000 consecutive intracapsular cataract extractions and found that most important intraoperative complications involved rup­ture of the capsule (6.5%) and vitreous loss (3%). The most important immediate postoperative complica­tions were delayed wound closure (2.7%), iritis (2.9%) and ocular hypertension (3.4%). Late complications were Irvine-Gass syndrome (2.8%), epithelial down growth in the anterior chamber (0.6%) and reti­nal detachment (2.0%). Alpha chymotrypsin often caused a temporary ocular hypertension (at least 25.2%). Functional results were very good where no preexisting ocular pathology existed; in 90% of cases the vision was 7/10 or more.

Palestra Oftalmologie Panamericana

Levy et al (Palestra Of tal mol Panamer 4:21, 1980) discussed the importance of having a deep anterior chamber following extraction of the cataract, especial­ly when intraocular lens implantation is to be per­formed. A deep anterior chamber prevents vitreous loss, makes placement of an intraocular lens easier and helps to protect the endothelium. Their study in­dicated that the excellent akinesia and patient relaxa­tion produced by general anesthesia resulted in deeper anterior chambers than with local anesthesia and ocular compression. In contradistinction to a com­monly held view that ocular rigidity is important with regard to vitreous loss and intraoperative anterior chamber depth, they found no evidence to support

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any predictive relationship between these two param­eters. It is well known that injection of a local anes­thetic increases volume and pressure within the orbit and thereby exerts pressure on the globe. This pres­sure in an open eye need not be very great to indent the wall of the globe and cause protrusion of the vitre­ous. Even with use of a balloon compressor on the eye at a periocular pressure of 100 mm Hg for ten minutes prior to surgery, anterior chambers were still shallower than with general anesthesia.

Canadian Journal of Ophthalmology

Cooper and Newfield (Can] Ophthalmol 16:1, 1981) described premarket review of intraocular lenses in Canada. Medical devices in Canada are sub­ject to the Food and Drug Act which is administered by the Health Protection Branch of the Department of National Health and Welfare. There has been consid­erable cooperation between the Bureau of Medical Devices and the Canadian Ophthalmological Society (COS); the activities of the Bureau have been molded to a large extent by the opinions of COS. A bureau representative has attended meetings of the intraocu­lar and contact lens committee, and many suggestions have been made to the bureau. The bureau's testing program for intraocular lenses is the result of a COS request. Visual inspection of surface finish during manufacture is difficult because of the size of the lens and shallow field of conventional magnifiers and mi­croscopes. A rapid, economical, reliable and nondes­tructive method of inspection that can be used during manufacture, for complete inspection oflenses has yet to be devised, although promising techniques using laser scattering are being developed in the United States. Lenses were examined in the author's study by projection, optical microscopy and scanning electron microscopy. The latter technique has the advantage of greater depth of field and, because the sample ap­pears opaque, good rendering of surface texture. However, the method is too time-consuming and ex­pensive for a large-scale sampling program and cannot be used in a quality controlled program since the me­tallic coating required would render the lens unusable for implantation. Lens power is tested on an optical bench. The uncertainty in locating the position for best focus can be greatly reduced by stopping down the lens to exclude the marginal rays, which are brought to a different focus. Lens power in aqueous is then calculated from conversion formulas involving the indices of refraction of the lens and the surround­ing medium. Because of the small dimensions in­volved, lens gauges are impractical for measuring ra­dius of curvature. Commercial instruments such as the radius cope and the toposcope, used for measuring

the radius of contact lenses, could not be used without modifications. However, the radius of curvature of a typical intraocular lens can be measured with fair ac­curacy by observing the angle of reflection of a laser beam incident on the surface. This technique is simi­lar to the study of Purkinje images of the eye by means of a phakoscope. A spot laser beam is reflected from the lens surface onto a screen. Movement of the lens moves the reflected spot on the screen and the radius of curvature can be calculated from the dis­placement of the spot as a function of lens position. Because most lens shapes are now fairly standard (plano-convex), the measurement of resolving power is therefore useful as an indication of finished quality rather than good optical design. Also, such figuring defects as cylinder distortion can be detected (though not easily measured) by checking for astigmatism. The apparatus used for measuring focal length (lens power) can also be used for testing resolVing power. A suita­ble target, such as the United States Air Force 1951 Lens Resolution Target is mounted so that the middle groups on the chart are imaged by the lens as spatial frequencies in the range of 200 to 300 line pairs per mm. The acuity of the retina is typically about 200 line pairs per mm.

Transactions of the Ophthalmological Societies

of the United Kingdom

Galin et al (Trans Ophthalmol Soc UK 100:229, 1980) discussed the mechanism of inflammation after IOL implantation, noting that the additional steps re­quired lead to greater inflammation in the immediate postoperative period than simple cataract extraction. This is further demonstrated by the higher incidence of sterile hypopyon in the implanted eye but late in­flammatory syndromes as well as the increased inci­dence of hypopyon suggest that more than trauma of insertion is involved. PMMA lenses with nylon-6 loops can activate the complement system and such activation occurs primarily at the loops. Mechanical trauma permits protein and cells to enter the eye. Some of these proteins are components of comple­ment, others are also present which can be activated and generate inflammatory mediating substances such as kallikrein and plasminogen activators. The comple­ment components which are in a precursor state are activated by a variety of substances, one of which may be the molecular configuration of the implant or its haptics. White blood cells are then attracted to the site and stimulated to aggregate and adhere to the of­fending substance. An attempt at phagocytosis occurs and lysosmal enzymes are discharged which can cause destructive effects on the surrounding tissues, includ­ing the cornea, vitreous and retina.

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Investigative Ophthalmology and Visual Science

Barzam et al (Invest Ophthalmol Vis Sci 19:1348, 1980) compared the intraocular concentrations of oxacillin given by continuous intravenous infusion, subconjunctival injection, or a combination in a rabbit model of Staph aureus endophthalmitis. Both meth­ods produced high levels in the cornea and aqueous and moderate concentrations in the choroid-retina, but vitreous penetration was poor with both. Com­bined therapy offered little advantage. The optimal therapy of bacterial endophthalmitis may require di­rect intravitreal injection of antibiotic.

Klinische Monatsblaetter fur Augenheilkunde

Merte and Merkle (Klin Monatsbl Augenheilkd 177:437, 1980) tested the long term lOP-lowering ef­fect of the beta-blocker Propranolol 0.5% drops over six years on 27 patients. These included angle-closure (8), open-angle glaucoma (14), congenital glaucoma (2), pigmentary glaucoma (2), and aphakic glaucoma (1). Propranolol decreased lOP without causing mio­sis, accommodative spasm or other irritating side ef­fects. In seven patients, however, pressure was not lowered sufficiently with each treatment. During the examination period the pulse rate was slowed and blood pressure reduced to a relatively minor extent which did not seriously affect circulation.

Clemente (Klin Monatsbl Augenheilkd 177:455, 1980) described goniotrapenation with a triangular scleral flap. The size of the usual 20 mm2 flap was re­duced by about one-half. Instead of the quadrangular flap, a lamellar triangular flap of 5 mm side length was prepared. The reduction of the flap and accordingly the scleral wound did not lead to any disadvantages. Advantages were a significant shortening of the filtra­tion path with less scarring tendency and a simpler way of preparing the flap. Also, in the combination of cataract and glaucoma operations the triangular flap was found to be useful.

Demmler (Klin Monatsbl Augenheilkd 177:523, 1980) studied the effect of Bupranolol eye drops on ten patients with open-angle glaucoma over six months. Bupranolol eye drops lowered lOP by about 15% over a prolonged period. Some patients needed treatment in .combination with miotics. Visual acuity and visual fields remained constant. As a rule, Bupranolol was tolerated well by the patients.

American Journal of Ophthalmology

Berger and Streeten (Am] Ophthalmol 91:630, 1981) reported two cases of fungal growth in aphakic hydrophilic contact lenses, and discussed other series, some of which had as high as 14% positive cultures for fungi after home sterilization. Both cases, and one previously reported, occurred with thicker aphakic contact lenses. Both patients had symptoms that cleared up rapidly after they discontinued wearing the contact lenses, but in neither case was there any evi­dence of fungal infection of the eye. This confirms the surprisingly small effect a continuous fungal inoculum has on the eye. Fungi often seem to be in the matrix of the contact lens and not on its surface, which offers the eye a margin of safety. In both cases, however, surface fungi were present so that the possibility of in­fection after abrasion was real. No conclusion can be drawn regarding the susceptibility of soft contact lenses to specific fungi as several different fungi have been found. Evidence suggests that thicker contact lenses are more susceptible to fungal growth, espe­cially when they are used for extended wear.

Eiferman (Am] Ophthalmol 92:328, 1981) studied the effect air has on human corneal endothelium by filling the anterior chamber completely with air dur­ing cataract extraction. This produced an average loss of 18.5% endothelial cells compared to 8.5% in a con­trol group. The same surgeon did the identical proce­dure, except for the air injection, in all cases. A pseudoguttata or "peau d' orange" appearance of the corneal endothelium was seen with air but disap­peared with resorption of the bubble.

Berkowitz et al (Am] Ophthalmol92:332, 1981) did fluorophotometric determination of the corneal epi­thelial barrier after penetrating keratoplasty and found that healed corneal transplants showed a per­meability 3.3 times that of normal eyes that had not undergone surgery. Partially healed corneal trans­plants were 67 times more permeable than control eyes and 20 times more than the healed transplants. This increase in permeability could result in intraocu­lar damage from topically applied medications. Topic­al corticosteroids can induce posterior subcapsular cataracts and glaucoma in susceptible people. Topical antibiotics are well tolerated in an eye with an intact epithelium, but could cause endothelial cell toxicity in an unhealed cornea. On the other hand, it could be worthwhile to lower required concentration of topical anti glaucoma eye drops in patients with epithelial de­fects. This could decrease systemic and ocular side ef­fects while remaining as effective therapeutically. Cardiac side effects with epinephrine and timolol could be increased in susceptible people.

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Krey (Am J Ophthalmol 92:378, 1981) found aber­rations of polarized light at the fixation points of the posterior loops as well as in the optical portion it­self and in the haptic loops of six styles of IOLs from four manufacturers . These represented changes of ori­entation in the molecular arrangement at locations subjected to mechanical stress. Small cracks at the loop fixation points in lenses implanted in two patients confirmed these polarized light findings .

Cobo and Forster (Am J Ophthalmol 92:59, 1981) observed that understanding of the dynamics of intravitreal gentamicin, as well as other antibiotics, has been based on data from studies in phakic, un inflamed rabbit eyes. This could be misleading as the establishment of a communication between the vitreous and the anterior chamber might cause more rapid clearance of the antibiotic from the vitreous into the aqueous circulation . This study showed that intravitreal gentamicin cleared more rapidly from the uninflamed aphakic rabbit eye (12 hour half-life) than the phakic control (32 hour half-life). A similar differ­ence was noted with experimental Staph aureus endo­phthalmitis. Presumably, removal of the lens allows faster diffusion into the anterior chamber where such drugs may be more rapidly cleared through the aque­ous circulation. Human data from nine aphakic in­fected eyes undergoing reinjection or vitrectomy indi­cated that therapeutic levels of gentamicin are not consistantly found 48 hours or more after the initial intravitreal injection. An optimal time for reinjection may be between 36 and 48 hours. Since clearance is slower in phakic eyes, it may be reasonable to post­pone reinjection for 72 to 96 hours .

Ophthalmology Rao et al (Ophthalmol 88:386, 1981) studied long­

term changes in corneal endothelium following intra­ocular lens implantation. They compared 52 eyes with intraocular lenses and 35 eyes with simple cataract ex­tractions using clinical specular microscopy. The en­dothelial photographs were obtained preoperatively, and at least four times in the postoperative period of each case, ranging from 16 to 43 months. The im­planted cases produced more endothelial cell damage and the deleterious effect was greatest with iris­supported lenses as compared with anterior chamber lenses. Seventy-one percent had precipitates on the endothelium with 16% developing guttata-like areas. All changes progressed with time and none occurred in eyes with simple cataract extraction. The progres­sive damage may be a result of chronic, smoldering uveitis associated with intraocular implants. (Ed. note: all cases reported had intracapsular cataract ex­traction. A comparison with extracapsular extrac­tion/capsule-supported IOLs would have been inter­esting).

Knolle (OphthalmoI88:407 , 1981) described a mod­ification of McCannel's suturing technique for dislo­cated IOLs wherein the initiallimbal corneal incision for passage of the suture needle was omitted. Instead, needle entry through the cornea and iris and then around the lens loop, and exiting through the cornea were performed first. The incision for suture retrieval was performed later. This avoided chamber shal­lowing the endothelial injury, as confirmed by endo­thelial cell counts .

Wilkinson (Ophthalmol 88:410, 1981) reviewed 70 pseudophakic retinal detachments and found that they were similar in characteristics to those following routine cataract extraction, but were somewhat more difficult to manage than the phakic variety, primarily because of difficulty in visualizing the peripheral reti­na. Also, there was some mild tendency for periretinal membrane formation in pseudophakic cases. Despite these problems, the repair rate closely approximated that for aphakic eyes. Visual results in pseudophakic eyes were somewhat lower than in comparable aphakic eyes . The presence of an IOL makes place­ment of intraocular gases at the time of vitrectomy for massive preretinal proliferation (MPP) much more difficult. Profound scleral indentation at the time of surgery is frequently necessary to bring the peripher­al retina of the pseudophakic eye into view. More cry­otherapy and more extensive buckles are frequently required in pseudophakic eyes than in aphakic cases.

Mackool (Ophthalmol 88:414, 1981) described the use of closed vitrectomy techniques on pseudophakic eyes to remove retropseudophakic membranes, to re­move vitreous strands that surrounded IOLs or that were adherent to the corneoscleral incision and iris in cases with persistent cystoid macular edema, to relocate IOLs which were dislocated into vitreous, and to relieve pseudophakic pupillary block. These techniques were also performed to remove vitreous in the anterior chamber prior to secondary IOL implan­tation. Closed vitrectomy was effective in improving visual acuity and reducing or eliminating CME in the five pseudophakic eyes. However, no patient achieved a final visual acuity of more than 20/40. Cor­neal edema did not occur when closed vitrectomy was performed prior to IOL insertion. This is in contrast to cases of "open-sky" approach in which superior cor­neal edema for one to three weeks following surgery was almost invariably present.

Polack et al (OphthalmoI88:425, 1981) used sodium hyaluronate (Healon) to restore the anterior chamber and replace vitreous following anterior vitrectomy in 30 penetrating keratoplasties. Balanced saline solu­tion was used as control in 20 keratoplasties. It was

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found that the Healon facilitated surgery in aphakic eyes and reduced the degree of endothelial trauma by decreasing the amount of manipulation of the graft when it is being sutured. Similar graft protection was observed in phakic eyes and in cases of combined graft with cataract surgery and 10L implantation. Corneal transplants were significantly thinner in the Healon­treated eyes than in the control eyes . The authors felt that corneal thickness measurements are the best in­dicator of endothelial function and these measure­ments are probably more important than cell count which at best samples a very small portion of the cor­neal tissue. In 33 Healon-treated eyes, lOP was in­creased in only two cases (40 mm Hg). These were early cases in which 0.5 ml or more was injected and since then they have removed Healon and exchanged BSS through a 27-gauge needle.

Hoffer et al (OphthalmoI88:729, 1981) reported re­sults of the UCLA clinical trial of radial keratotomy. Patients excluded were those under the age of 18, those with myopia less than 2 diopters or progressive myopia, those with astigmatism over 4 diopters, and those with a history of any eye disease other than mild amblyopia. Data was collected on 52 eyes of the first 43 patients three months after surgery. No patients were excluded or lost to follow-up. All had preoperative, uncorrected visual acuity less than 20/200; postoperative uncorrected acuity was 20/20 or better in 25% and 20/40 or better in 52%. Twenty­seven percent had uncorrected acuity between 20/50 and 20/100. Best-corrected acuity decreased in 20% but the maximum decrease in any eye was one line of Snellen letters. Preoperative mean refractive error was - 4.9 diopters and postoperatively, the mean de­crease ill myopia was 3.4 diopters. Postoperatively, 25% had hyperopia of + 0.25 to + 3.25 diopters but all could accommodate to 20/20 without glasses. De­crease in myopia achieved did not correlate with steepness of corneal curvature, corneal diameter, or scleral rigidity. Significant glare was present in 20% and annoying variable visual acuity in 10%.

Perl et al (Ophthalmol 88:774, 1981) studied 180 consecutive corneal transplants performed by one sur­geon to determine the benefit obtained by using a 0 .5 mm oversize (OS) graft. Same size (SS) grafts were compared to OS grafts. Refractive error, recovery of visual acuity, and lOP were similar, but astigmatism was found to be significantly greater in the OS group. OS grafts did not protect against postkeratoplasty glaucoma or decrease recovery time.

Kramer (Ophthalmol 88:782, 1981) studied cystoid

macular edema after aphakic penetrating keratoplasty and found that transpupillary anterior vitrectomy at the time of penetrating keratoplasty, as compared with no vitreous manipulation, seemed to contribute to a high incidence of postoperative persistent CME. Whenever possible the vitreous should remain undisturbed during CPKP. Appropriate surgical measures include: use of a scleral support firmly su­tured to the sclera; preoperative or intraoperative ad­ministration of carbonic anhydrase inhibitors and/or osmotic diuretics; digital massage after completion of a trephine groove but before entrying the anterior chamber; the use of an oversize donor corneal button, and constant care to maintain the anterior chamber throughout surgical manipulations. In addition, non pupillary routes for excision of vitreous should be considered when vitreous excision is made unavoida­ble by vitreous prolapse or anticipated prolapse. These include aspiration of fluid vitreous through the pars plana and/or pars plana vitrectomy with a vitreous cutting instrument before or after extraction. Finally, extracapsular cataract extraction in CPKP may help by maintaining an intact posterior capsular boundary while protecting the anterior vitreous face .

Abbott (Ophthalmol 88:788, 1981) studied patients with unilateral corneal edema and clinically normal fellow eyes, with specular microscopy. Clinically unrecognized endothelial disease was proposed as a cause for this unilateral corneal edema and was verified by light and electron microscopic studies. The pathologic findings varied somewhat from Fuch's dystrophy and may represent either a variant or a form of endothelial cell degeneration of as yet unde­termined etiology. The fellow eyes had endothelial pleomorphism and reduced counts in the nonedematous cornea, and no history of previous eye disease, trauma, inflammation or surgery. These con­ditions were not detectable in the nonedematous cor­nea by standard high magnification biomicroscopy and required the clinical specular microscope to confirm the diagnosis.

Foulks (Ophthalmol 88:801, 1981) described treat­ment of recurrent corneal erosion and corneal edema with topical osmotic colloidal solution. These were well tolerated and effective in treating corneal erosion but did not reduce symptoms or improve vision in cases of corneal edema due to endothelial decompen­sation. This suggests that the solutions have a signifi­cant dehydrating effect when edema results solely from epithelial abnormalities .

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