Assessment of the rate of non-responders to latanoprost therapy

Purpose: To determine the rate of non-responders to latanoprost therapy in patients with POAG or OHT. Methods: Two hundred and eighty newly diagnosed untreated POAG-OHT consecutive patients or patients treated only with a beta-blocker were enrolled in the study after proper wash-out. Ten academic italian centres participated in this study. All patients were put on latanoprost therapy for one month. Patients were divided into 3 groups according to the level of IOP reduction after one month of latanoprost therapy: non-responders (IOP reduction < 15%), responders (IOP reduction > 15% but < 30%), and hyper-responders (IOP reduction > 30%). Non-responders entered a randomized cross-over study in which the efficacy of timolol, brimonidine, and pilocarpine was tested. Each treatment period lasted 30 days. Iris colour, axial length, refraction, gonioscopy were the variables tested as predictors of treatment efficacy in lowering IOP. Results: Mean baseline IOP was 23.6 mmHg (sd 2.7) and, after 1 month of therapy with latanoprost, mean IOP was lowered to 16.8 mmHg (sd 2.6) with an average effect of 28.8%. Non-responders rate was 4.6%, while hyper-responders were 27% of the patients. Non-responders had a significant reduction of IOP after brimonidine (p < 0.05), while after timolol and pilocarpine the decrease in IOP did not reach statistical significance. Conclusions: A low rate of non-responders to latanoprost was found in this multicentric prospective study; in non-responders patients only brimonidine, as compared with timolol and pilocarpine, was able to effectively lower IOP.