Effects of the Timolol-Dorzolamide Fixed Combination and Latanoprost on Circadian Diastolic Ocular Perfusion Pressure in Glaucoma

Abstract

To evaluate the effect of the timolol-dorzolamide fixed combination (TDFC) and latanoprost 0.005% on 24-hour intraocular pressure (IOP), systolic (SBP) and diastolic (DBP) blood pressure, and diastolic ocular perfusion pressure (DOPP) in patients with primary open-angle glaucoma (POAG). This was an institutional, randomized clinical trial. After a 24-hour assessment without treatment, 27 previously untreated patients with POAG were randomized to 6 weeks' treatment with twice-daily TDFC (8 AM and 8 PM) followed by once-daily latanoprost 0.005% (8 PM), or vice versa. One eye was analyzed per patient. The mean values of IOP, DBP, SBP, and DOPP (difference between DBP and IOP) were recorded at each time point, and the 24-hour data are the mean values of each patient's measurements over the 24-hour period. The differences between the values of the first treatment period and the baseline and the second treatment period and washout were calculated and analyzed by means of an analysis of variance model that tested the effects of sequence and treatment. Both treatments significantly reduced 24-hour IOP (P < 0.0001), but TDFC led to lower 24-hour pressure (mean +/- SD: 15.4 +/- 1.9 vs. 16.7 +/- 1.7 mm Hg; P = 0.004). Latanoprost did not lead to any significant reduction in mean 24-hour SBP and DBP (SBP: P = 0.952; DBP: P = 0.831), but TDFC did (SBP and DBP: P < 0.0001). Both treatments significantly increased 24-hour DOPP (P < 0.0001), with no difference between the two medications (P = 0.09). In previously untreated patients with POAG, TDFC, and latanoprost equally enhanced 24-hour DOPP: the former by counteracting the decrease in DBP with a substantial reduction in IOP and the latter by not affecting DBP and significantly reducing IOP. (isrctn.org number, ISRCTN67123277.).