Recurring transitory blindness caused by primary marginal pigment epithelial iris cysts

PURPOSE: To report four cases of primary pupillary pigment epithelial iris cysts, all members of one family, in which two of the patients had recurring transitory visual impairment. METHODS: Observational case series. History was taken, the patients were examined with slit-lamp and ultrasound biomicroscopy, and surgically removed cyst tissue was examined with transmission electron microscopy. RESULTS: Pupillary pigment epithelial cysts of the iris generally show an autosomal dominant heredity pattern, with occasional lack of penetrance. In two of our cases, the size and location of the cysts caused visual symptoms, necessitating surgical removal. The cyst wall consists entirely of pigment epithelial cells. CONCLUSION: The origin of pupillary pigment epithelial cysts is unclear, and a hereditary background is very likely. Their clinical significance is in their similarity to pigmented tumors of the iris. They may also be indicative of coexisting systemic disease. In symptomatic cases, treatment is indicated.