Comparison of the effects of travoprost, latanoprost and bimatoprost on ocular circulation: a 6-month clinical trial

Purpose: To study the effect of three prostaglandin F2-alpha (PG) analogues on retrobulbar blood flow velocity in previously untreated patients with primary open-angle glaucoma (POAG) or ocular hypertension (OHT), using colour Doppler ultrasound. Methods: Sixty newly diagnosed patients with POAG or OHT were randomly assigned to travoprost 0.004% (n = 12 with POAG, n = 8 with OHT), latanoprost 0.005% (n = 11 with POAG, n = 9 with OHT) and bimatoprost 0.03% (n = 13 with POAG, n = 7 with OHT) treatment groups in a double-masked fashion. At baseline examination, blood pressure, heart rate and intraocular pressure (IOP) were recorded. Peak-systolic and end-diastolic velocities were measured in the ophthalmic (OA), central retinal (CRA) and temporal short posterior ciliary arteries (PCA). The resistive index (RI) and ocular perfusion pressure (OPP) were determined for each treatment group. After a treatment period of 6-months, all procedures were repeated. Results: There were no significant differences in age (53 +/- 14 years in the travoprost group, 51 +/- 14 years in the latanoprost group, 53 +/- 11 years in the bimatoprost group), gender (11 men, nine women; 11 men, nine women; 13 men, seven women, by group, respectively), or clinical diagnosis (POAG or OHT) among treatment groups (p > 0.05). A significant decrease in IOP (baseline: 26.4 +/- 3.3 mmHg, 26.8 +/- 1.3 mmHg, 25.8 +/- 1.8 mmHg, respectively; month 6: 20.9 +/- 1.9 mmHg, 20.8 +/- 2.4 mmHg, 18.3 +/- 1.2 mmHg, respectively; p < 0.0001) and an increase in OPP (baseline: 33.7 +/- 3.8 mmHg, 33.5 +/- 3.2 mmHg, 33.9 +/- 2.6 mmHg, respectively; month 6: 40.2 +/- 3.5 mmHg, 39.9 +/- 3.1 mmHg, 41.7 +/- 2.6 mmHg, respectively; p < 0.0001) were verified in all three groups during the study period. Mean baseline RI values for the CRA in the travoprost group and the OA in the latanoprost group were both 0.7 +/- 0.1 mmHg and both values were statistically significantly lower at 6 months (0.6 +/- 0.1 mmHg in both groups; p = 0.002, p < 0.0001, respectively). In the bimatoprost group there was no statistically significant difference in haemodynamic parameters over the study period (p > 0.05). Conclusions: Our results suggest that the three PG analogues significantly reduce IOP and increase OPP in patients with POAG or OHT. Topical travoprost and latanoprost significantly reduce the RI of the CRA and OA, respectively. We were unable to determine any effect of topical bimatoprost on ocular haemodynamics.