Short-term ocular tolerability of dorzolamide 2% and brinzolamide 1% vs placebo in primary open-angle glaucoma and ocular hypertension subjects.

PURPOSE: To compare ocular tolerability of dorzolamide 2%, brinzolamide 1%, and placebo given three times daily.

METHODS: A prospective, double-masked, three-centre, crossover comparison in which 25 ocular hypertensive or primary-open angle glaucoma subjects were randomized to receive dorzolamide, brinzolamide, or placebo three times daily for 3 days. Intraocular pressure, visual acuity, a visual analogue scale, and ocular and systemic symptom queries were completed at the end of each period.

RESULTS: After chronic dosing, there was a significant difference in ocular pain on the visual analogue scale among the groups at the 10-s postinstillation time point with dorzolamide having the highest level (22.5+/-28.9) compared to brinzolamide (5.0+/-8.7) or placebo (3.2+/-10.4) (P=0.0006). No differences between groups were observed preinstillation nor following dosing at 3 or 10-min postinstillation. On the initial instillation, the 10-s postinstillation pain was rated as 43.3+/-77.1, which was significantly higher than after chronic dosing (P=0.017). On the ocular symptom query, dorzolamide had the highest incidence of burning/stinging and redness compared to the other groups, but was generally characterized as mild. There were no significant differences in the visual acuity at any time point.

CONCLUSIONS: This study suggests that subjects treated with dorzolamide suffer more ocular pain upon instillation compared to brinzolamide or placebo. However, pain symptoms are fewer following chronic dosing and are generally characterized as mild.