Lens Induced Glaucomas
LENS INDUCED GLAUCOMA
Lens-induced glaucoma may occur as either secondary angle-closure or open-angle glaucoma.The angle-closure can be caused by lens swelling (phacomorphic glaucoma) or lens dislocation (ectopia lentis). The open-angle include glaucoma related to: leakage of lens proteins through the capsule of a mature or hypermature cataract (phacolytic glaucoma), obstruction of the trabecular meshwork following cataract extraction, capsulotomy, or ocular trauma by liberated fragments of lens material (lens-particle glaucoma), and hypersensitivity to own lens protein following surgery or penetrating trauma (phacoantigenic glaucoma). The pathophysiology, diagnosis and treatment of these different lens-induced glaucomas will be reviewed in this article (1-4).
LENS INDUCED SECONDARY ANGLE-CLOSURE GLAUCOMA
Pathophysiology Phacomorphic glaucoma is a lens-induced secondary angle-closure glaucoma that may occur as a result of mature cataract formation. Narrowing of the angle can occur slowly with formation of the cataract by pushing the iris forward or acutely precipitated by an intumescent cataractous lens leading to obstruction of aqueous flow between the border of the pupil and the anterior capsule of the lens (pupillary block) (1, 4, 5)
Diagnosis Phacomorphic Glaucoma is diagnosed by the presence of eye pain, history of decreased vision, evidence of mature cataract formation (slit lamp exam), angle closure (gonioscopy), and elevated intraocular pressure (applanation tonometry) in the affected eye. Distinguishing factors between primary angle-closure and phacomorphic angle-closure are presence of an intumescent cataractous lens and presence of cell and flare. Axial length measurement (usually short in phacomorphic) and records of the refraction may also be helpful in distinguishing between the two conditions (2, 4, 5, 8)
Management Initial treatment of phacomorphic glaucoma is to lower the intraocular pressure with medical therapy such as topical beta blockers, carbonic anhydrase inhibitors and hyperosmotic agents such as oral glycerin. Parasympathomimetic agents should be used with caution since they can precipitate pupillary block. If the intraocular pressure is not controlled with medical therapy alone, a laser iridotomy is usually performed, other options include corneal depression with a Zeiss 4-mirror lens. If the fellow eye is also predispose to angle closure glaucoma, prophylactic laser iridotomy should be performed. Definitive treatment consists of cataract extraction (4-8).
Glaucoma induced by Lens-dislocation
Pathophysiology Secondary angle-closure glaucoma may occur if the lens is displaced from its normal anatomical position (Ectopia lentis). Forward displacement of the lens may result in narrowing of the anterior chamber angle and pupillary block causing secondary angle-closure. Ectopia lentis may be present as an isolated clinical entity secondary to trauma or associated with systemic disorders such as Weill-Marchesani syndrome, Marfan's syndrome, homocystinuria, among others. The biochemical defects in these conditions result in defective lens fibers (zonular fibers that suspend the lens in position), often causing subluxation/dislocation of the lens, thus increasing the risk of secondary angle-closure (1, 8-13)
Diagnosis The clinical presentation of Ectopia lentis varies according to the individual state of the lens but when dislocation of the lens results in angle-closure and pupillary block, patients usually present with a painful eye, decreased visual acuity, and history of difficulties with accomodation and near vision. Diagnosis is made by the presence of a dislocated/subluxated lens, angle-closure, and intraocular pressure elevation in the affected eye (2, 8-9).
Management The management of glaucoma induced by ectopia lentis depends on the degree of lens dislocation and the presence of pupillary block. In cases of partial subluxation without pupillary block, conservative treatment with intraocular pressure monitoring could be followed. If pupillary block is present, a laser iridectomy is usually indicated. When total anterior dislocation occurs, removal of the lens is the definitive treatment (2, 8-9).
LENS INDUCED OPEN-ANGLE GLAUCOMA
Pathophysiology Phacolytic glaucoma is caused by an inflammatory process caused by the leakage of lens material through the capsule of a mature cataract. The released lens material is composed of altered lens protein, macrophages, and other inflammatory cells that lead to trabecular meshwork obstruction and precipitate glaucoma. (1-4, 8, 14-16) The American Academy of Ophthalmology's Pathology Atlas contains a virtual microscopy image of Phacolytic Glaucoma.
Diagnosis The typical presentation of Phacolytic glaucoma is a painful eye with photophobia, decreased vision, and severe conjunctival hyperemia. Diagnosis is usually made by the presence of prominent cell or white material/particles in the anterior chamber, flare reaction without keratic precipitates, corneal edema, increased intraocular pressure, and evidence of a mature Pseudohypopyon may also be present (lens protein deposits layering in the inferior angle). Gonioscopy reveals an open anterior chamber angle. (1-4, 8, 14)
Management Patients with phacolytic glaucoma should be treated initially with topical cycloplegia, topical steroids, and aqueous suppressants. The immediate goal of therapy is to reduce the inflammation and to reduce the intraocular pressure. Cataract extraction is the definitive treatment for phacolytic glaucoma (1-4, 8, 14)
Pathophysiology Lens particle glaucoma, in contrast to phacolytic glaucoma, is secondary to a "disruption of the lens capsule", which may occur after cataract surgery, penetrating lens injury, or laser posterior capsulotomy. The disrupted lens releases lens particle material in the anterior chamber leading to the obstruction of the aqueous outflow (1-3,8)
Diagnosis The presentation is usually delayed for a few weeks after the precipitating event, but it may occur months or years later. A history of surgery or trauma is an important element in making an accurate diagnosis. Clinical findings include elevated intraocular pressure and evidence of cortical lens material in the anterior chamber. Other possible signs are corneal edema, synechiae, and cell/flare reaction in the anterior chamber. (2, 3,8,17-19)
Management Medical therapy is initially aimed to control the intraocular pressure, topical steroids may be given to reduce inflammation, and mydriatics to prevent synechiae formation. If the lens particle/material does not resorb, there is a large amount of lens material in the anterior chamber and the intraocular pressure cannot be controlled, surgical removal of the lens is undertaken (1-3,17-19)
Phacoantigenic Glaucoma (formerly known as Phacoanaphylaxis)
Pathophysiology Phacoantigenic glaucoma is a granulomatous inflammatory reaction directed against own lens antigens leading to obstruction of the trabecular meshwork and increased intraocular pressure. It is important to mention that phacoanaphylaxis is not the correct name of this condition since it is not an allergy. The mechanism causing the reaction seems to be an Arthus-type immune complex reaction mediated by IgG and the complement system (1, 3,8,20-24)
Diagnosis Phacoantigenic glaucoma usually occurs between one and fourteen days after cataract surgery or trauma. Clinical findings include "keratic precipitates", anterior chamber cell/flare reaction, synechiae and residual lens material. Less common is the presence of Glaucomatous optic neuropathy (1-3, 8)
Management Initial therapy is to control the intraocular pressure with IOP-lowering medications and to reduce the inflammation with topical steroids. If medical treatment is unsuccessful, surgical removal of residual lens material is indicated (1-3,8,22)
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