Patients with pigment dispersion syndrome are frequently encountered in clinical practice. Iris abnormalities and the absence of key features of pigment dispersion syndrome can guide the discovery of secondary causes of pigmentary glaucoma, such as peripheral iris pigment epithelial cysts.
The purpose of this study was to describe a patient initially diagnosed as having primary pigmentary glaucoma found to have multiple bilateral peripheral iris pigment epithelial cysts causing pigment liberation, focal angle closure, and advanced secondary glaucoma.
A 64-year-old man presented for follow-up after a recent diagnosis of primary pigmentary glaucoma in the left eye. Clinical examination revealed transillumination defects of both irides and a heavily pigmented trabecular meshwork. A midperipheral bulge of the iris was appreciated in the superior temporal quadrant of the left eye. Gonioscopic evaluation showed that the bulge focally obstructed the angle. Anterior segment optical coherence tomography demonstrated a normal iris insertion of both eyes, with the exception of a steepened approach superotemporally in the left eye. Ultrasound biomicroscopy revealed bilateral small- to medium-sized peripheral iris pigment epithelial cysts and confirmed a large cyst superotemporally in the left iris.
This case describes a patient with advanced secondary pigmentary glaucoma from iris pigment epithelial cysts. The mechanisms of glaucoma are likely twofold: (1) pigment liberation from the cysts contacting the lens zonules and, to a lesser extent, (2) focal angle closure at the site of the large peripheral cyst. The key features of pigmentary glaucoma, namely, posterior bowing of the iris, may not be present in secondary pigment dispersion. This case highlights the importance of careful evaluation of the iris and angle in making a correct diagnosis. The choice of topical agent to control intraocular pressure while not increasing the size of these cysts is also an important consideration.