Glaukoma Fakogenik

01Pathophysiology

Phacogenic glaucoma is not a single disease but a group of secondary glaucomas where the crystalline lens is the direct causative agent. Understanding which lens mechanism is at play is the key to answering vignettes correctly.

Phacomorphic glaucoma occurs when a cataractous lens swells and becomes intumescent. The enlarged lens pushes the iris forward, narrowing and eventually closing the iridocorneal angle. This creates a secondary angle-closure glaucoma through pupillary block. The mechanism is purely mechanical: a bigger lens occupies more space in the anterior segment, and aqueous humor cannot drain. This is why you see a shallow anterior chamber on exam. The contralateral eye typically has a deeper anterior chamber and a normal or early cataract, which is an important distinguishing feature from primary angle-closure glaucoma (where both eyes tend to have anatomically narrow angles).

Phacolytic glaucoma occurs with a hypermature or morgagnian cataract. The lens capsule remains intact but becomes permeable to high-molecular-weight lens proteins. These proteins leak into the anterior chamber and are engulfed by macrophages. The swollen, protein-laden macrophages physically obstruct the trabecular meshwork, blocking aqueous outflow. The angle remains open on gonioscopy, but drainage is impaired by cellular debris. Clinically, this produces a heavy anterior chamber flare with floating white particles and sometimes a pseudohypopyon composed of macrophages rather than true inflammatory cells.

Lens particle glaucoma follows trauma or cataract surgery where residual cortical lens fragments remain in the anterior chamber. These fragments directly clog the trabecular meshwork. The angle is open, and you can often see visible lens material on slit-lamp examination. The timeline is important: it develops days to weeks after surgery or penetrating injury.

Phacoantigenic (phacoanaphylactic) uveitis with secondary glaucoma is a granulomatous inflammatory response directed against the patient's own lens proteins. It occurs after lens capsule disruption (trauma or surgery) exposes previously sequestered lens antigens to the immune system. The resulting zonal granulomatous inflammation centered on the lens raises IOP through inflammatory debris and trabecular swelling. This is the only phacogenic mechanism that is truly immune-mediated.

02Classification and Clinical Manifestation

The critical distinction for exam purposes is between phacomorphic (angle closure, mechanical) and phacolytic (open angle, protein/macrophage-mediated). A vignette describing an elderly patient with a long-neglected cataract presenting with acute painful vision loss will test whether you can differentiate these two based on gonioscopy findings and lens appearance.

03Diagnostic Workup

The best initial test is a thorough slit-lamp examination combined with tonometry. In phacomorphic glaucoma, the swollen cataractous lens and shallow anterior chamber are apparent on slit-lamp alone. In phacolytic glaucoma, slit-lamp reveals heavy flare with iridescent or refractile particles floating in the anterior chamber, often with a visible hypermature cataract showing a wrinkled capsule.

Gonioscopy is essential to classify the mechanism. It distinguishes phacomorphic (closed angle) from phacolytic and lens particle types (open angle). Without gonioscopy, the treatment approach cannot be properly directed.

The most accurate confirmatory test for phacolytic glaucoma, when the clinical picture is ambiguous, is anterior chamber paracentesis with cytologic examination. Finding macrophages laden with phagocytosed lens material confirms the diagnosis. However, this is rarely needed in clinical practice when the presentation is classic: hypermature cataract plus open angle plus heavy flare with particles.

For phacomorphic glaucoma, comparison with the contralateral eye is a high-yield diagnostic step. If the fellow eye has a deep anterior chamber and a wide-open angle, this strongly supports a lens-induced mechanism rather than primary angle-closure disease.

04Management and Treatment

Acute stabilization always comes first. The goal is to lower IOP rapidly using a combination of aqueous suppressants (timolol, brimonidine, carbonic anhydrase inhibitors) and, if needed, hyperosmotic agents like intravenous mannitol. Topical steroids are started simultaneously to control intraocular inflammation, which is present in all subtypes to varying degrees.

For phacomorphic glaucoma, if pupillary block is the dominant mechanism and the IOP remains refractory to medical therapy, a laser peripheral iridotomy (LPI) can be considered as a temporizing measure to break the pupillary block. However, LPI alone does not resolve the problem because the intumescent lens continues to crowd the angle. Definitive treatment remains cataract extraction.

For phacolytic and lens particle glaucoma, topical pilocarpine is generally avoided because it worsens inflammation and can exacerbate the condition. The inflammation must be controlled with steroids before proceeding to surgery. Miotics are also contraindicated in phacomorphic glaucoma because they worsen pupillary block.

The definitive and curative treatment for all forms of phacogenic glaucoma is surgical removal of the offending lens. In phacomorphic glaucoma, this relieves the mechanical angle crowding. In phacolytic glaucoma, removing the lens eliminates the source of leaking proteins. In lens particle glaucoma, irrigation and aspiration of retained cortical fragments resolves the obstruction. Once the lens is removed, IOP typically normalizes, and long-term antiglaucoma medications are usually not required unless there has been irreversible trabecular damage from prolonged elevation.

05Differential Diagnosis and Distractors

06Traps and High-Yield Pearls

The most common trap in phacogenic glaucoma questions is confusing phacomorphic with primary acute angle-closure glaucoma. Both present with a painful red eye, elevated IOP, and a shallow anterior chamber. The test-writer will embed a clue about a mature or visibly swollen cataract in one eye and a normal-depth chamber in the fellow eye. If you reflexively pick "acute angle closure" without checking the contralateral eye description, you fall into the trap. The discriminator is always the asymmetry: primary angle closure is bilateral anatomical predisposition, phacogenic is unilateral lens pathology.

A second common pitfall is using pilocarpine in the acute management. In primary angle closure, pilocarpine is part of the treatment to constrict the pupil and pull the iris away from the angle. In phacomorphic glaucoma, pilocarpine worsens the pupillary block by increasing lens-iris contact. In phacolytic glaucoma, pilocarpine exacerbates inflammation. If the vignette asks for the next step in management and pilocarpine is an option alongside cataract extraction, choose the surgery.

The third pearl is recognizing that cataract extraction is the definitive treatment for all subtypes. Medical therapy only temporizes. A question asking "what is the most appropriate long-term management" is always answered with lens removal, not chronic IOP-lowering drops.

Finally, remember the classic phacolytic triad: hypermature cataract + open angle on gonioscopy + heavy flare with refractile particles. If the vignette describes a wrinkled lens capsule or a morgagnian cataract (liquefied cortex with a sinking nucleus), you are being pointed toward phacolytic glaucoma, and the confirmatory finding is macrophage-laden aspirate on paracentesis.