Secondary Open-Angle Glaucoma
Jonathan S. Myers
Scott Fudemberg
PIGMENT DISPERSION SYNDROME
Pigment dispersion syndrome (PDS) is a condition in which an abnormal amount of pigment is dislodged from the pigmented epithelium on the posterior surface of the iris and then deposited on various structures throughout the anterior segment. Obstruction of the trabecular meshwork by pigment, and subsequent damage to the meshwork, can lead to elevated intraocular pressure (IOP) and secondary open-angle glaucoma.
Epidemiology
• PDS occurs most frequently in young (aged 20 to 45 years), myopic, Caucasian men.
• Approximately one-third of PDS patients go on to develop pigmentary glaucoma.
Pathophysiology
Currently, it is believed that the iris of predisposed individuals is abnormal and also posteriorly bowed so that the iris pigment epithelium contacts underlying packets of lens zonular fibers, leading to liberation of the pigment into the aqueous.
Pigment becomes trapped in and damages the trabecular meshwork, leading to reduced aqueous outflow, increase in IOP, and, ultimately, optic nerve damage if uncontrolled.
History
• Myopia and a family history of glaucoma
• Jarring exercise, strenuous physical activity, or, rarely, dilation may lead to dramatically increased pigment dispersion, a so-called pigment storm, leading to sudden elevations of IOP. Patients may then experience blurred vision and headaches.
Clinical Examination
• Slit lamp (Figs. 13-1, 13-2, 13-3, 13-4, 13-5, 13-6 and 13-7): Characteristic findings include Krukenberg spindle (pigment carried from the posterior iris surface by aqueous convection currents passes through the pupil and deposits on the central corneal endothelium in a vertical pattern), pigment deposition on the anterior surface of the iris (usually concentric rings in furrows on the iris surface), mid-peripheral iris transillumination defects (best seen on retroillumination with a small beam through the pupil), and pigment deposition on the
zonular fiber attachments near the equator of the lens (also called a Scheie stripe).
zonular fiber attachments near the equator of the lens (also called a Scheie stripe).
• Gonioscopy: Patients typically have posterior bowing of the peripheral iris, leading to lens-iris contact. The angle is very widely open, with moderate to heavy pigmentation, which is relatively homogeneously spread over the entire circumference of the angle. A Sampaolesi line is often present and represents pigment deposition on Schwalbe line.
• Posterior pole: Characteristic glaucomatous optic atrophy is seen with prolonged elevation of IOP or intermittent pressure spikes. Myopic patients, and possibly especially those with PDS, are prone to peripheral retinal tears, necessitating close examination.
Treatment
• The goal of therapy is to control IOP in patients with significantly elevated pressure or glaucomatous nerve changes, usually through aqueous suppressants.
• Miotics reduce pigment shedding and reduce IOP, but are often poorly tolerated in this young population and may increase the risk of retinal detachment while making monitoring of the retina periphery more difficult.
• Laser peripheral iridotomy also may reduce pigment shedding, because it allows the posteriorly bowed iris to move anteriorly as any built-up fluid pressure in the anterior chamber is then normalized with the posterior chamber (relief of the so-called reverse pupillary block). This may help prevent glaucoma in individuals at higher risk but who have not yet developed uncontrolled pressure (although clear evidence supporting iridotomy in pigmentary glaucoma is lacking).
• Laser trabeculoplasty is effective, although there are reports of increased postoperative elevations in IOP. Lower energies are indicated to reduce the risk of pressure spikes, given the heavily pigmented trabecular meshwork.
• Efficacy of glaucoma filtration surgery in these patients is similar to that in primary open-angle glaucoma.
BIBLIOGRAPHY
Campbell DG. Pigmentary dispersion and glaucoma: a new theory. Arch Ophthalmol. 1997;97:1667.
Gandolfi SA, Vecchi M. Effect of a YAG laser iridotomy on intraocular pressure in pigment dispersion syndrome. Ophthalmology. 1996;103:1693-1695.
 FIGURE 13-1. Krukenberg spindle. A vertical endothelial deposition of pigment characteristic of pigment dispersion syndrome (PDS). It may slowly resolve when pigment shedding stops but may persist for many years or forever. Pattern of deposition is thought to be related to convection currents of aqueous within the eye. |
 FIGURE 13-2. Transillumination defects in pigment dispersion syndrome (PDS). Marked peripheral and mid-peripheral transillumination defects in PDS. Many patients may present with only several mild radial spoke-like defects. |
 FIGURE 13-3. Pigment dispersion syndrome, dense pigmentation, and Krukenberg spindle. Krukenberg spindle (foreground), heavily pigmented deep angle (background). Characteristic homogeneous dense pigmentation of trabecular meshwork. |
 FIGURE 13-4. Pigment dispersion syndrome, pigment deposition. Pathology specimen showing pigment deposition on trabecular meshwork and anterior to meshwork. |
 FIGURE 13-5. Pigment dispersion syndrome, pigment deposition. Pathology specimen showing pigment deposition within beams of trabecular meshwork. |
 FIGURE 13-6. Pigment dispersion syndrome, Zentmeyer line. Deposition of pigment near equator of lens, at insertion of lens zonular fibers. Variously referred to as Zentmeyer line or Scheie stripe. |
 FIGURE 13-7. Pigment dispersion syndrome (PDS), bowing of peripheral iris. A. Ultrasound biomicroscopy (UBM) of patient with PDS, showing backward-bowing peripheral iris in contact with lens surface. B. UBM of the same patient, following iridotomy, showing anterior relaxation of iris with reduced contact with lens. |
PSEUDOEXFOLIATION SYNDROME
Pseudoexfoliation syndrome (PXFS) is a systemic condition that can lead to secondary open-angle glaucoma. The characteristic flaky white pseudoexfoliation material, seen throughout the anterior segment, can obstruct the trabecular meshwork and has also been isolated in tissues throughout the body.
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