Effect of Latanoprost on the Diurnal Variations in the Intraocular and Ocular Perfusion Pressure in Normal Tension Glaucoma

PURPOSE: To evaluate the effects of latanoprost on the diurnal variations in the intraocular pressure (IOP) combined with the ocular perfusion pressure (OPP) in patients with normal tension glaucoma (NTG). PATIENTS AND METHODS: Twenty-two eyes from 22 patients with NTG were used for the study. The diurnal variations in the IOP and blood pressure (BP) were measured every 3 hours without therapy, and then the patients were treated with latanoprost (0.005%) once daily for more than 12 weeks. The diurnal variations in the IOP and BP under medication were again measured every 6 hours. The diurnal variation of IOP for 24 hours, mean diurnal IOP, maximum IOP, minimum IOP, range of variation in IOP, OPP, and BP were compared between the baseline and after treatment by means of a paired t test. RESULTS: At 3 months after the start of the latanoprost treatment regimen, the IOP showed a statistically significant decrease at every assessed time point over 24 hours (P<0.001). Latanoprost significantly reduced the mean diurnal IOP, maximum IOP, minimum IOP, and mean range of variation in the IOP values from baseline (P<0.001, <0.001, <0.001, and 0.009, respectively). OPP after treatment showed no significant difference at any assessed time points from the baseline (P>0.1). Latanoprost did not significantly alter the mean diurnal OPP (P>0.1), and BP (P>0.5) from the baseline. CONCLUSIONS: Latanoprost was thus found to significantly reduce IOP over 24 hours, whereas it does not affect OPP and BP in NTG patients. Therefore, it may be a useful medication for NTG.