Reduction of intraocular pressure with treatment of latanoprost once daily in patients with normal-pressure glaucoma

Purpose: Currently available ocular hypotensive agents often fail to lower intraocular pressure (IOP) in patients with normal-pressure glaucoma (NPG). The authors evaluated the IOP-reducing potential and side effects of latanoprost, a newly developed ocular hypotensive agent, in this patient group. Methods: A randomized, double-masked, placebo-controlled cross-over study was performed in 30 patients with NPG, 29 of whom completed the study. During three periods of 3 weeks each, patients received, in a random order, 50 mu g/ml latanoprost once daily, 15 mu g/ml latanoprost twice daily, and placebo. Per dose, one drop of the study medication was applied topically in both eyes. At the end of each treatment period, diurnal IOP measurements were obtained. General and ocular symptoms were recorded, and a detailed ocular examination was performed on each visit to monitor side effects. Results: Average IOP reduction after 50 mu g/ml latanoprost once daily, 15 mu g/ml latanoprost twice daily, and placebo was 3.6 +/- 1.0 mmHg (21.3%, P < 0.001), 2.4 +/- 1.5 mmHg (14.2%, P < 0.001), and 0.4 +/- 1.8 mmHg (2.4%, not significant), respectively. The difference between the two latanoprost dose regimens was significant (P = 0.001). Efficacy of latanoprost correlated with initial IOP (r(2) = 0.76, P < 0.001). A mild, but statistically significant, increase in conjunctival hyperemia was observed in both latanoprost treatment groups. Conclusion: Both latanoprost regimens significantly reduce IOP in patients with NPG, but 50 mu g/ml latanoprost once daily is more effective in reducing IOP than 15 mu g/ml latanoprost twice daily. Lowering the concentration did not result in an improved side effects profile. Latanoprost is more effective at higher IOP levels.