Purpose: The aim of the study was to assess efficacy and side effects of latanoprost during two years of treatment.
Methods: The study was a randomized, parallel group, double-masked, multicenter comparison between latanoprost and timolol in patients with open angle glaucoma or ocular hypertension, followed by an open-label 18-month extension during which all patients were treated with latanoprost.
Results: Latanoprost caused a marked and sustained reduction of the intraocular pressure (IOP). IOP was reduced from baseline levels 25.1+/-3.5 mm Hg (mean+/-SD) in 183 patients initially randomized to treatment with latanoprost to 17.4+/-2.9 mm Hg (n=66) after 24 months of treatment. For patients initially randomized to treatment with timolol the corresponding figures were 24.3+/-2.3 mm Hg (n=72) and 17.4+/-2.6 (n=41) mm Hg after 18 months of treatment with latanoprost. Two patients were withdrawn because of uncontrolled IOP and 11 patients required additional timolol treatment to maintain an adequate IOP control. Patients initially treated with timolol and switched to latanoprost had a further reduction of the IOP of 1.0 mm Hg after 6 months of treatment with latanoprost (p<0.005). 46 patients were withdrawn from the study, mostly due to increased iris pigmentation or an iris color with known high risk of developing increased pigmentation. 22 patients developed increased pigmentation of the iris. The follow-up revealed no previously unknown ocular or systemic side effects.
Conclusion: Once daily applications of latanoprost cause a marked and sustained reduction of the IOP. The only clinically significant side effect noted was the increased pigmentation of the iris, most frequently seen in irides with a mixture of brown and blue/gray or green colors. No systemic side effect was observed.