Evidence of Early Change in Iris Color With Latanoprost Use Latanoprost, a 17-phenyl–substi- tuted analog of PGF 2 a, has been shown to effectively lower intraocu- lar pressure in clinical trials and darken the irides in both subhu- man primates and humans. 1 The re- ported time of onset of the change in iris color has been noted to be as early as 3 months. To our knowl- edge, this case represents the earli- est reported change in iris color following the initiation of latano- prost use. Report of a Case. A 78-year-old white woman was first seen in 1986 complaining of worsening vision, which was found to be secondary to nuclear sclerosis involving her right eye. She underwent an uncompli- cated extracapsular cataract extrac- tion with intraocular lens implan- tation in December 1988. Prior to surgery, she had intraocular pres- sure in the midteens and small sym- metric cups with healthy neuroreti- nal rims. In 1992, she had elevated intraocular pressure in the right eye in the high 20s to low 30s. On vi- sual field testing, she demonstrated a nasal step. The patient was then given timolol maleate twice daily in the right eye. Her intraocular pres- sure was maintained in the high teens to low 20s using this treat- ment regimen until she was seen in 1993 with evidence of progression of her visual field defect. In 1994, the medical therapy was changed to 1% pilocarpine hydrochloride 4 times daily. During a 3-year period, the op- tic nerve of her right eye pro- gressed with evidence of vertical elongation and a superior rim de- fect. In 1996, after a course of dor- zolamide hydrochloride was given in the right eye 3 times daily with minimum improvement, the pa- tient was then given latanoprost in the right eye only for a 4-week pe- riod. The iris color in the right eye was the same as the left eye at that time. During the 4-week period, the patient’s iris color changed from blue-green to brown-green. Use of the medication was subsequently discontinued (Figure). Comment. Alm et al 1 summarized the results of 198 patients who pre- viously participated in the original phase 3 clinical trials that assessed the safety and efficacy of latano- prost. Photographs of the iris were not taken prior to 2 months after the initiation of treatment. Darkening of the iris occurred in 14 patients (7%) at 6 months and in 24 patients (12%) after 1 year of treatment. The au- thors noted that nevi or freckles did not increase in size and the likeli- hood of change was greatest in those patients who had heterogeneous pig- mentation at baseline. The adverse effect is likely related to an increase in melanin production in the mela- nocytes of the iris stroma. In the case presented herein, the patient was unilaterally treated, thus the slightest change in iris color could be detected early. At base- line, the patient had an iris color with mixed pigmentation, placing her at high risk for the development of this adverse effect. This report differs from previous reports in that the on- set of change occurred after 4 weeks of treatment. Previous reports 2 in subhuman primates noted the change after at least 6 weeks of treat- ment. We noted no change in the lashes, which may be related to the short exposure to the drug. 3 Regine M. Pappas, MD Sharon Pusin, MD Eve J. Higginbotham, MD Baltimore, Md Dr Higginbotham was an investiga- tor in the phase 3 clinical trial and is currently an investigator in the com- bined latanoprost-timolol study, which is sponsored by Pharmacia-Upjohn, Kalamazoo, Mich. Her expenses for Magnified view of the affected right eye (left) and unaffected left eye (right). CASE REPORTS AND SMALL CASE SERIES ARCH OPHTHALMOL / VOL 116, AUG 1998 1115 ©1998 American Medical Association. All rights reserved. Downloaded From: https://jamanetwork.com/ on 02/16/2022