Analysis of irises with a latanoprost-induced change in iris color.

To study the histologic aspects of irises subjected to extended latanoprost treatment. Prospective, observer-masked study. Iris biopsies of eyes treated with latanoprost were analyzed (all had a photographically documented increase in iris pigmentation) plus control eyes (untreated with prostanoids) using optical microscopy. PATIENT OR STUDY POPULATION: There were 14 study eyes treated with latanoprost and 8 untreated control eyes. The morphologic characteristics of the irises. The irises treated with latanoprost had an increased number of melanocytes with nuclear inclusions, granules of melanin in the vascular walls and the melanocytes and free granules in the stroma compared with control eyes (P = .001, P = .01, P = .004, P = .01, respectively, by the chi(2) test). Chronic therapy with latanoprost appears to induce more changes in the iris than a simple increase in the melanin content of the melanocytes.