The effect of latanoprost on ocular blood flow

Purpose To investigate the effect of latanoprost on ocular hemodynamics in healthy subjects. Methods In a randomized, double-masked, placebo-controlled crossover study, 12 healthy subjects received either placebo or latanoprost for 4 weeks in one randomly chosen eye. Following a 4-week washout period, each patient received the opposite treatment. Blood pressure, heart rate, logMar visual acuity, contrast sensitivity, iris photography, intraocular pressure (IOP), Heidelberg retinal flowmetry, and color Doppler imaging measurements were taken at baseline and post-treatment. Heidelberg retinal flowmetry images were analyzed using the pixel-by-pixel analysis. Color Doppler imaging measurements included peak systolic velocity and end diastolic velocities (cm/s), and the calculated resistance index. Pre- and post-treatment values were compared by Wilcoxon signed rank tests (P < 0.05 was considered to be statistically significant). Results There were no significant changes in heart rate, blood pressure, contrast sensitivity, or visual acuity with either treatment. Latanoprost demonstrated a significant reduction in both IOP (P = 0.005) and retinal blood flow at the 10th (P = 0.009) and 25th (P = 0.009) percentiles of Heidelberg retinal flowmetry measurements in the superior temporal region. Latanoprost, however, did not reduce blood flow in the inferior temporal region and did not significantly elevate the percentage of zero-flow pixels of the temporal peripapillary area. Conclusion Latanoprost has mostly neutral effects on ocular circulation. These findings must be investigated in glaucoma patients who may respond differently than healthy subjects due to faulty vascular autoregulation.