ABSTRACT
OBJECTIVE: To investigate by masked electron microscopy whether 6 months of topical latanoprost caused pathological changes in the peripheral iris of patients with glaucoma. METHODS: Seventeen patients with bilateral primary open-angle glaucoma requiring trabeculectomy were recruited for this study. The iridectomy taken during surgery on the first eye served as a control. The second test eye was treated topically with latanoprost for 6 months before its trabeculectomy. Fourteen patients completed the treatment arm of the study, and 1 of these underwent marked color change. As a result, 31 iridectomy specimens were fixed, coded, and evaluated. RESULTS: The specimens were evaluated for evidence of stromal inflammation, vascular alterations, and stromal and posterior epithelial degeneration. None of these features was evident in any of the 31 iridectomy specimens. There was evidence of the incidence of free melanin granules in the stroma, melanin turnover, abundance of stromal clump cells, atypical cellular features in melanocytes, and prominence of the anterior border. After code breaking, it was evident that none of these features distinguished the test from the fellow irises in our group. The patient with color change in the test iris did not stand out from the others in this analysis. Qualitative reexamination of further sections after unmasking gave the impression of increased melanin granule numbers in the melanocytes of the anterior border region. CONCLUSIONS: The ultrastructure of the iridectomies from the latanoprost-treated eyes and the fellow eyes conformed to published standards for normal iris. There was no evidence of early ultrastructural changes, which might have been the harbingers of latanoprost-induced iris abnormality.
