Incidence of a Latanoprost-Induced Increase in Iris Pigmentation in Japanese Eyes

Abstract

To prospectively determine the incidence of a latanoprost-induced increase in iris pigmentation in Japanese brown iris eyes by identifying changes in iris pigmentation on a series of iris color photographs. In a cohort study, we prospectively and consecutively enrolled 104 patients (104 eyes) with primary open-angle glaucoma or normal-tension glaucoma who began treatment with latanoprost eye drops for the first time. None of the enrolled patients had a history of previous intraocular surgery or laser surgery. Patients comprised 51 men and 53 women. Their ages ranged from 23 to 80 years (mean +/- SD, 63.8 +/- 10.4 years). Before and every 3 months after starting latanoprost treatment, iris photographs were taken using a slit-lamp biomicroscope with an attached camera. To identify an increase in iris pigmentation, seven glaucoma specialists independently read the series of photographs. If five of the seven observers agreed that iris pigmentation had increased, we determined that the iris pigmentation had increased from the time the previous photograph was taken. Ten normal volunteers served as controls, and photographs of their eyes were used in the evaluation of iris pigmentation. The Kaplan-Meier life table analysis was adopted to evaluate the incidence of increase in iris pigmentation during treatment with latanoprost. The Kaplan-Meier life table analysis indicated that the incidence of increased iris pigmentation at 3, 6, 9, 12, and 15 months after the start of latanoprost treatment was 16.3%, 34.2%, 49.5%, 58.2%, and 58.2%, respectively. Latanoprost instillation for at least 1 year induced increased iris pigmentation in approximately 50% of the treated Japanese eyes, which is a considerably higher percentage than that reported in Caucasians.