Pigmentary Glaucoma: Board Review
Master pigmentary glaucoma signs, mechanism and pseudoexfoliation clues for NBEO, OKAP and international eye-care board exams.
Which slit-lamp finding is classically associated with pigment dispersion syndrome?
Pigmentary Glaucoma in 30 Seconds
Pigmentary glaucoma is the glaucomatous stage of pigment dispersion syndrome. Pigment released from the posterior iris pigment epithelium accumulates within the trabecular meshwork, impairing aqueous outflow and raising intraocular pressure. Think: young myopic man, deep anterior chamber and dense angle pigment.
The Mechanism
Pigment dispersion syndrome results from posterior bowing of the peripheral iris, a mechanism called reverse pupillary block, in which aqueous flow from the posterior to the anterior chamber creates a relative pressure gradient that pushes the iris posteriorly and increases iridozonular contact. The iris rubs against zonules, releasing posterior iris pigment epithelium granules. Pigment accumulates within the trabecular meshwork and impairs aqueous outflow. Exercise or vigorous pupillary dilation, whether physiologic or pharmacologic, can release a sudden pigment burst and cause an acute intraocular pressure spike. It classically affects young myopic males.
Classic Examination Findings
- Krukenberg spindle: vertical, fusiform pigment on central corneal endothelium. Aqueous convection currents deposit pigment in this characteristic vertical pattern on the corneal endothelium.
- Midperipheral, spoke-wheel iris transillumination defects from loss of posterior iris pigment epithelium.
- Dense, homogeneous trabecular meshwork pigmentation on gonioscopy, often circumferential and most marked inferiorly. This pattern is more irregular or patchy in pseudoexfoliation.
- Pigment on the zonules and anterior or posterior lens capsule, including a peripheral posterior capsular ring called Scheie's line, though this is less consistently present than the Krukenberg spindle or iris transillumination defects.
4 Facts Exams Always Ask
- The classic patient is a young to middle-aged myopic male with a deep anterior chamber and posterior iris concavity, related to reverse pupillary block.
- Iridozonular contact liberates iris pigment. Vigorous exercise or pharmacologic or physiologic pupillary dilation can increase pigment release and produce transient blurred vision, halos or an intraocular pressure spike.
- Gonioscopy shows dense, homogeneous trabecular pigmentation. Pseudoexfoliation typically produces more irregular or patchy trabecular pigmentation with pseudoexfoliative material at the pupillary margin and anterior lens capsule, and usually affects older patients.
- Pigment dispersion syndrome may have normal intraocular pressure and no optic nerve damage. It becomes pigmentary glaucoma only when elevated intraocular pressure causes characteristic glaucomatous optic neuropathy. Pigment liberation often decreases with age as the crystalline lens enlarges and the iris flattens, though established glaucomatous damage does not reverse.
The Classic Trap
Do not diagnose pseudoexfoliation glaucoma solely because the angle is pigmented. Pigmentary glaucoma occurs in younger, often myopic patients and has a concave iris, radial midperipheral transillumination defects and a Krukenberg spindle. Pseudoexfoliation usually affects patients over 60 and shows flaky pseudoexfoliative material on the lens capsule or pupillary margin, poor dilation and more asymmetric disease.
Clinical Pearl
A patient can have dramatic pigment dispersion without glaucoma. Diagnose pigmentary glaucoma only after confirming pressure-related glaucomatous optic nerve and visual field damage. Dense pigmentation alone is pigment dispersion syndrome, not glaucoma. Laser peripheral iridotomy can reduce posterior iris bowing in selected eyes, though it is not routinely recommended to prevent glaucoma progression and evidence for its benefit remains limited.
Checkpoint 1
Which combination of findings is most typical of pigment dispersion syndrome?
Checkpoint 2
A 35-year-old myopic male has Krukenberg spindle, dense trabecular meshwork pigmentation, and mid-peripheral iris transillumination defects. Which additional gonioscopic finding is most characteristic of pigment dispersion syndrome?
A 29-year-old myopic man reports brief blurred vision after basketball. Intraocular pressure is 33 mmHg in the right eye. Slit-lamp examination shows a vertical corneal pigment spindle and radial midperipheral iris transillumination defects. Gonioscopy shows a wide-open angle with heavy, uniform trabecular pigmentation. His optic disc has early inferior rim thinning.
What is the most likely diagnosis?
Sources & Reviewer Info
References
- Niyadurupola N, Broadway DC. "Pigment dispersion syndrome and pigmentary glaucoma: a major review." Clinical and Experimental Ophthalmology. 2008;36(9):868-882.
- Scuderi G, Contestabile MT, Scuderi L, Librando A, Fenicia V, Rahimi S. "Pigment dispersion syndrome and pigmentary glaucoma: a review and update." International Ophthalmology. 2019;39(7):1651-1662.
- Sivaraman KR, Patel CG, Vajaranant TS, Aref AA. "Pigment dispersion syndrome: a brief overview." Journal of Clinical and Translational Research.
- Jiwani AZ, Faiq MA, Dada T, et al. "Genetic Basis of Pigment Dispersion Syndrome and Pigmentary Glaucoma: An Update and Functional Insights." Genes.
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