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Aims: The aim of this study was to compare the effects of brimonidine and timolol on retinal nerve fiber layer (RNFL) thickness in ocular hypertensive patients.

Methods: This was a prospective, comparative, and unmasked study. For 12 months, 38 eyes of 19 patients with primary open-angle glaucoma received brimonidine tartrate 0.2%, and 40 eyes of 20 patients received timolol maleate 0.5%. Intraocular pressure (IOP) was measured every 2 months, and RNFL thickness was assessed using Scanning laser polarimetry (GDx) at baseline and at 12 months.

Results: Mean IOP reduction was similar in both groups. Within each treatment group, the RNFL thickness for ellipse average (P = 0.004), superior (P = 0.035), temporal (P = 0.003), inferior (P < 0.0001), and nasal averages (P = 0.044) were significantly decreased from baseline in timolol at 12 months. However, the RNFL thickness for ellipse average and four quadrants showed no significant change from baseline in brimonidine. The between-group difference in RNFL change showed a significant reduction for ellipse average (P = 0.02), temporal (P = 0.005), and inferior averages (P = 0.016) following timolol therapy, as compared to brimonidine.

Conclusions: There appear to be less progression for RNFL damage following brimonidine 0.2% therapy compared to timolol 0.5% in ocular hypertensive patients over 1 year. This finding does not correlate with IOP reduction.