Comparison of the Effect of Latanoprost 0.005% and Timolol 0.5% on the Calculated Ocular Perfusion Pressure in Patients With Normal-tension Glaucoma

To compare the calculated mean ocular perfusion pressure at the end of 3 weeks' treatment with latanoprost 0.005% once daily or timolol 0.5% twice daily in normal-tension glaucoma patients.In a three-center, double-masked, randomized, crossover study, 36 patients were allocated to two treatment groups; one received 3 weeks each of placebo, latanoprost, placebo, and timolol, whereas the other group had placebo, timolol, placebo, and latanoprost. Intraocular pressure and resting systemic blood pressure were measured at 9 AM, 12 noon, and 4 PM. Ocular perfusion pressure was calculated for each time period as well as the mean of three values (daytime average). Systemic blood pressure and heart rate were also recorded at 30-minute intervals during the last 24 hours of each treatment period.The average daytime mean ocular perfusion pressure (mean +/- SEM) following latanoprost treatment was 53.2 +/- 1.4 mm Hg, an increase of 8% from the latanoprost run-in period, compared with 50.9 +/- 1.1 mm Hg following timolol treatment, an increase of 2% from the timolol run-in period (P.05, ANOVA). Timolol reduced the blood pressure. The difference in mean daytime and nighttime systolic blood pressure measurements as well as nighttime diastolic blood pressure was about 5 mm Hg between the latanoprost and timolol treatments. The daytime and nighttime heart rates were also slower during the timolol treatment.Because ocular perfusion pressure may be important in some glaucomatous patients, latanoprost appears to affect ocular perfusion pressure more favorably than timolol does in patients with normal-tension glaucoma.