A 7 year prospective comparative study of three topical β blockers in the management of primary open angle glaucoma

Abstract

Aim - To determine the long term efficacy of monotherapy with topically applied β blocking agents and to determine whether selective β blockers were able to preserve the visual field more effectively than non-selective agents. Method - A prospective randomised, open, comparative study of three topically applied β blockers - timolol, betaxolol, and carteolol - was carried out on 153 patients (280 eyes) with newly diagnosed open angle glaucoma. Those patients who were not withdrawn were followed by the same observers for a minimum of 2 years and a maximum of 7 years, with clinical observations, Goldmann tonometry and 24.2 Humphrey visual field analysis. Results - All three drugs lowered the IOP significantly from untreated levels but betaxolol took up to 12 months in some instances to reach the maximum pressure reduction. After 7 years only 43% of the eyes begun on timolol, 34% of those started on carteolol, and 29% of those on betaxolol were still being treated with these medications alone. Visual fields were analysed throughout the trial by CPSD and MD and at the end by linear regression analysis (PROGRESSOR). The visual fields remained the same without apparent improvement or deterioration throughout the period of follow up. Eight patients (11 eyes) were withdrawn because of continuing field loss in spite of reduction in IOP (six using carteolol and five using betaxolol). Conclusions - Analysis shows that less than half the eyes initially treated with topical β blockers might be expected to still be being treated with their original medication after 5 years. The rest required either additional medication or trabeculectomy. There was no statistically significant improvement or deterioration in the visual fields over a 7 year period. On the evidence of this trial there are no particular advantages in using selective blockers.