Intraocular Pressure-lowering Efficacy of Dorzolamide/Timolol Fixed Combination in Normal-tension Glaucoma

Purpose: To investigate the intraocular pressure (IOP)-lowering efficacy and safety of dorzolamide/timolol fixed combination (DTFC) in patients with normal-tension glaucoma (NTG). Methods: An open-label, 12-week, 2-center study was conducted. Thirty-seven patients with treatment-naive NTG received DTFC for 12 weeks to reduce IOP. Primary outcome measures were changes in IOP from baseline to 12 weeks of treatment at a peak drug effect. Secondary outcome measures were changes in IOP from baseline to 12 weeks of treatment a trough drug effect and 8 hours after drug administration. At each visit, IOP was measured at 9 AM and then DTFC was administered by a hospital personnel. IOP was also measured at 11 AM and 5 PM At week 12, the IOP was measured at 1 and 3 PM as well. Results: The IOP at peak drug effect (11 AM) at 12 weeks was significantly reduced to 11.9 +/- 2.6mm Hg from the baseline of 15.6 +/- 2.5mm Hg (23.7%, P < 0.0001). Significant reduction in the IOP was also achieved at trough drug effect (9 AM) and at 8 hours after drug administration (5 PM) at 12 weeks (20.5% and 24.4%, respectively, all P < 0.0001). Eye irritation (59.5%) was the most frequently reported adverse event followed by ocular hyperemia (16.2%). The majority of eye irritations were mild in intensity. No patients discontinued the DTFC due to an adverse event and no systemic adverse event was considered related to study medication. Conclusions: DTFC is a safe and effective IOP-lowering agent in patients with NTG.