Comparative Evaluation of Bimatoprost Monotherapy in Primary Chronic Angle Closure and Primary Open Angle Glaucoma Eyes: A Three-Year Study

AIMS: The aim of this study was to compare the long-term efficacy of bimatoprost 0.03% monotherapy in primary open angle glaucoma (POAG) versus primary chronic angle closure glaucoma (PCACG) eyes. METHODS: A total of 55 consecutive primary adult glaucoma patients on bimatoprost monotherapy were prospectively evaluated in this 3-year, open-labeled, uncontrolled study. The primary outcome was the evaluation of a difference in the response to therapy of POAG eyes, as compared to PCACG eyes over a follow-up of 3 years. RESULTS: In the POAG group, the mean intraocular pressure (IOP) at the 36-month followup was found to be increased by 2.10 (+/-3.90) mmHg (confidence interval [CI], 0.975-4.185), compared to the mean IOP at 1 month (P = 0.047). In the PCACG group, the mean IOP at the 36-month follow-up was increased by 3.66) (+/- 3.34) mmHg (CI, 6.241-1.092), compared to the mean IOP at 1 month (P = 0.011). This upward drift in IOP was higher in the PCACG group, compared to the POAG group, but this was not statistically significant (P = 0.54). Patients with POAG and PCACG showed a 50% and 40% chance of having an IOP of <18 mmHg with bimatoprost monotherapy (P = 0.23), respectively, at the 3-year follow-up. CONCLUSIONS: This study showed that bimatoprost 0.03% monotherapy significantly lowers IOP in both POAG and PCACG eyes over a period of 3 years, though its efficacy appeared to decrease over time, to a similar extent, in both groups.