LENS-INDUCED UVEITIS

ROHIT.UDAYA.PRASAD

3224

Lens-Induced Uveitis-

•Phacoanaphylactic Uveitis -• It is an immunological response to lens proteins

in the sensitized eyes presenting as severe granulomatous anterior uveitis .

•Phacotoxic Uveitis – • It is an ill understood entity. This term is used to

describe mild iridocyclitis associated with the presence of lens matter in the anterior chamber either following trauma or extra-capsular extraction or leak from hyper-mature cataracts

•INTRODUCTION – • Lens-induced uveitis occurs in the setting of a ruptured or

degenerative lens capsule and is characterized by a granulomatous antigenic reaction to lens protein. Before the modern era of microsurgery, this disease was more common, and the diagnosis was often made histologically, as eyes with phacoanaphylaxis were often enucleated for intractable inflammation and secondary glaucoma.

• While lens fragments may be retained in the anterior or

posterior chamber during seemingly uncomplicated cataract surgery, they also may be dislocated posteriorly into the vitreous cavity during phacoemulsification of the nucleus, usually after zonular dehiscence or posterior capsule rupture. Lens-induced uveitis may develop, and the degree of intraocular inflammation in these patients often is governed by the size of the retained lens fragment, the time since cataract surgery, the patient's individual inflammatory response, and the extent of other intraocular manipulations.

•Pathogenesis -• The term phacoanaphylaxis is probably inappropriate because

no evidence exists of a classic type I immunoglobulin E (IgE) mediated anaphylactic reaction. The immunopathogenesis of lens-induced uveitis is believed to be the result of autosensitization to lens proteins. After a break in the lens capsule and sensitization to lens proteins, an immune complex–mediated phenomenon develops, which can be transferred by hyperimmune serum. Type II, III, and IV hypersensitivity reactions may be involved in the pathogenesis.

• The disease most likely is induced by altered tolerance to lens protein and not as a result of a rejection phenomenon of sequestered foreign materials. The specific type of immunological reaction in lens-induced uveitis may vary from patient to patient, and it may depend on the type of surgery or injury, the amount of retained lens in the vitreous cavity, and the previous immunological status of both the patient and the eye.

•Age: lens-induced uveitis are more common in the elderly population, with a peak incidence in the sixth to seventh decades.

•Sex: No sexual predilection exists are more common in younger age groups.

•Causes:• Lens-induced uveitis is usually the result of traumatic or

surgical disruption of the lens capsule and liberation of lens proteins into the aqueous or into the vitreous cavity. Posterior capsular rupture during phacoemulsification is the most common cause of posterior displacement of lens fragments. This complication is more common in patients with pseudoexfoliation syndrome, zonular dehiscence, a small pupil, friable iris, and hard nuclei or hypermature cataracts.

• Penetrating injury of the globe may result in severe lens-induced uveitis. The uveitis may remain undiagnosed clinically because of hyphema, decreased corneal clarity, and inflammation related to the trauma. A small punctured perforation site may remain unnoticed initially, and severe inflammation and cataract will be present 1 week later.

•History-• Lens-induced uveitis typically develops 1-14 days

after traumatic or surgical perforation of the lens capsule. In rare instances, the inflammation may develop several months after the disruption of the lens capsule.

• Clinical symptoms may include severe light sensitivity, epiphora, pain, floaters, loss of vision, and redness of the eye.

• Decreased vision may be due to refractive error (myopic or hyperopic shift) associated with such factors as macular edema, hypotony, or change in lens position.

• Visual acuity in patients with phacoanaphylactic uveitis is quite variable, ranging from 20/20 to no light perception.

•Clinically:

• The inflammation can vary from a mild anterior uveitis to a fulminant endophthalmitis. Typically, the inflammation is unilateral and involves only the traumatized eye.

• The most important clinical signs of lens-induced uveitis are lid swelling, perilimbal or diffuse injection, corneal haze, keratic precipitates (granulomatous),cells and flare, fibrin in the anterior chamber (occasionally), peripheral anterior synechiae, posterior synechiae, pupillary membrane, and iris nodules.

• In the posterior segment, lens fragments, inflammatory cells, traction bands in the vitreous, retinal edema, inflammatory cuffing of blood vessels, cystoid macular edema, and epiretinal membrane formation can be observed.

• If untreated, lens-induced uveitis/phacoanaphylactic endophthalmitis may result in chronic cystoid macular edema, cyclitic membrane formation, tractional retinal detachment, and phthisis bulbi.

Phacoanaphylactic reaction to penetrating injury of lens. This patient was a 25-year-old woman whose eye was penetrated with a 27-gauge needle during an attempt to anesthetize the eyelid for chalazion removal. One week later, a marked uveitis was present. Notice posterior synechiae.

• Typical appearance of retained lens fragments in posterior vitreous cavity. Lens material is a whitish substance that

obscures fundus details.

• Patient with persistently elevated intraocular pressure after cataract surgery was found to have retained lens material and low-grade inflammation. Retained lens

material is visible in retroillumination on downgaze

Typical clinical picture of retained lens material following cataract surgery. White cortical material is easily visible in the pupillary space

•Lab Studies:

•Aqueous paracentesis in subtle or early cases may reveal inflammatory cells and particulate lens proteins without bacteria. This procedure is performed more efficiently at the time of anterior chamber washout and vitrectomy to remove the inciting lenticular antigens

•Imaging Studies:

• If the media opacity prevents an appropriate fundus examination, echography with A-scan and B-scan may be helpful when evaluating the posterior pole.▫ Suspicion for acute endophthalmitis, intraocular foreign body,

dropped lens nucleus, thickening of the choroid, retinal detachment, and choroidal effusion are all indications for echography if the anterior segment changes hinder examination of the posterior segment.

▫ The shape, position, and thickness of the traumatized lens; the presence of focal echogenic areas; and, sometimes, even the entrance and exit wounds are recognizable by ultrasound. It is clinically important to diagnose the isolated rupture of the posterior capsule of the lens by echography. Such ruptures are characterized by the irregular extension of the highly reflective posterior capsule toward the vitreous with significantly increased thickness of the lens.

• Ultrasound biomicroscopy (UBM) may have an important role in the evaluation of lens-induced uveitis after extracapsular cataract extraction, revealing hidden lens particles in the posterior chamber causing inflammation as well as lens-particles creating secondary glaucoma

•Medical Care:• Treatment may be medical or surgical. Medical therapy of

phacoanaphylactic uveitis includes topical corticosteroids and may include cycloplegics and medication for elevated intraocular pressure as needed. Treatment should be tailored to the individual patient and adjusted according to response. Patient age, immune status, and tolerance for adverse effects always must be taken into account.

• Cycloplegics: Topical cycloplegics break or prevent the formation of posterior synechiae, stabilize the blood-aqueous barrier leading to reduced leakage of plasma proteins, increase uveoscleral outflow, and provide mild relief of ciliary spasm pain. The stronger the inflammatory reaction, the more frequently applied or stronger the cycloplegic.

• Corticosteroids: Corticosteroids block the formation of arachidonic acid from cell membrane precursors by inhibiting the action of phospholipase-A2, cyclooxygenase, and lipoxygenase. Thus, arachidonic acid is the premier precursor of potent inflammatory mediators, such as prostaglandins, thromboxane, and leukotrienes. Corticosteroids frequently are used in uveitis therapy. Topical steroid drops are given in dosages ranging from once daily to hourly. They also can be given in an ointment form. Periocular corticosteroids generally are given as depot-steroid injections when a more prolonged effect is needed or when a patient is noncompliant or poorly responsive to topical administration.

• Intraocular pressure–lowering agents: When phacoanaphylaxis is associated with high intraocular pressure ,aqueous suppressants are indicated. Beta-blockers, alpha-agonists, and carbonic anhydrase inhibitors are used to lower the pressure.

•Surgical Care:• If persistent or uncontrolled inflammation or elevated intraocular

pressure is not responsive to medical therapy or if such a large amount of exposed lens material is present that medical therapy is likely to fail, then surgical removal of the exposed lens material is indicated . The most common situation leading to this is posterior capsular rupture with the loss of lens fragments into the vitreous cavity during phacoemulsification . Removal of retained lens fragments by pars plana vitrectomy generally restores good visual function and reverses many complications in these patients. Surgical removal of retained lens material may be necessary depending upon the degree of inflammation, the size of the retained lens particle, and the presence of increased intraocular pressure. Observation is indicated when the lens fragments are small and the inflammation can be controlled.

• Retained lens fragments that are larger than one third to one half of the total cataract usually (but not always) require surgical removal.

• Several studies demonstrate no advantage to early surgery; therefore, the cataract surgeon may treat patients with retained lens fragments conservatively, and then refer the patient to a vitrectomy surgeon after an appropriate period of observation and medical therapy, unless the patient develops retinal detachment, highly elevated intraocular pressure, or some other condition in which posterior segment surgery is indicated more urgently.

•Complications:

• Cystoid macular edema:• Secondary glaucoma

▫ Trabecular meshwork obstruction may occur with the accumulation of white blood cells (macrophages and activated T lymphocytes) or their aggregations. These may cause peripheral anterior synechiae and subsequent closed-angle glaucoma.

▫ Obstruction may arise from inflammatory debris (eg, proteins, fibrin, high molecular weight proteins) and from lens particles. These proteins increase the aqueous viscosity, which may contribute to increased intraocular pressure.

▫ Leakage of lens proteins through the injured lens capsule with or without leakage of serum proteins from uveal blood vessels in lens-induced uveitis may block the trabecular outflow causing secondary glaucoma.

• Retinal detachment

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