Circadian changes of intraocular pressure and ocular perfusion pressure after timolol or latanoprost in Caucasians with normal-tension glaucoma

Purpose To evaluate the circadian effects on intraocular pressure (IOP) and ocular perfusion pressure (OPP) of 0.5% timolol or 0.005% latanoprost in Caucasian patients affected by normal-tension glaucoma (NTG). Patients and methods In this crossover trial, 30 consecutive NTG subjects underwent three 24-hour assessments of IOP, blood pressure (BP), heart rate (HR), and OPP [calculated according to the formula OPP = (1/3 systolic BP + 2/3 diastolic BP) x 2/3 – IOP]: at baseline, and after 1-month treatment with timolol or latanoprost. These parameters were recorded at 4 a.m., 8 a.m., noon, 4 p.m., 8 p.m., and midnight. Results Both timolol and latanoprost reduced IOP (p < 0.001), with a difference in favour of latanoprost of 1.3 mmHg (95% CI 0.9, 1.6; p < 0.001). After timolol, BP and HR decreased with respect to baseline (p < 0.001). Latanoprost increased mean OPP (3.6 mmHg, 95% CI 2.9, 4.3; p < 0.001), whereas timolol did not improve it. Conclusions Latanoprost induces an IOP reduction greater than timolol, also achieving a better circadian flattening of the IOP curve. Only latanoprost significantly increased mean 24-hour OPP. The management of Caucasian NTG patients should be critically realized, considering the 24-hour influence of each IOP-lowering drug on the ocular blood perfusion.