Longitudinal observation of the retinal nerve fibre layer in glaucoma patients treated with brimonidine combined with timolol or timolol alone

INTRODUCTION. The aim of the study was to evaluate the retinal nerve fibre layer (RNFL) thickness loss in primary open-angle glaucoma (POAG) patients treated topically with anti-glaucoma drops containing brimonidine and timolol combination or solely timolol. MATERIALS AND METHODS. Retrospective case series study of patients with POAG diagnosis followed up for a five-year period. Inclusion criteria were fulfilled by a group of 98 patients consisting of 53 combination and 45 monotherapy treatments. Intraocular pressure (IOP) at the level of 21 mm Hg or below for each measurement was observed in 52 patients, while incidences of pressure above 21 mm Hg were measured in 46 patients. POAG diagnosis was based on standard optical coherence tomography, IOP, and visual field examinations. RESULTS. Mean annual loss of RNFL thickness in the overall study group (if IOP levels are not taken into consideration) treated with timolol monotherapy was 1.8 ± 1.5 μm, while in group treated with brimonidine + timolol combination therapy it was 1.7 ± 1.5 μm (p > 0.05). In selected groups of patients with incidents of pressure rises, the mean annual loss of retinal nerve fibre layer thickness was 1.8 ± 1.6 and 1.9 ± 1.4 μm, respectively, for the monotherapy and combination therapy groups (p > 0.05). In the group of patients with no reported IOL rises, mean annual loss of RNFL thickness was 1.8 ± 0.9 and 1.1 ± 0.4 μm, respectively, for the monotherapy and combination therapy groups (p < 0.01). No significant differences were observed for the visual field mean deviation. CONCLUSIONS. POAG patients with low values of IOP might achieve slower progression of RNFL thinning on brimonidine combined with timolol therapy.