Timolol treatment of chronic open-angle glaucoma and ocular hypertension. A 2.5-year multicenter study.

Maintenance effect of topical timolol was investigated for 2 years in a group of 125 glaucomatous and ocular hypertensive patients (231 eyes) who had been successfully treated with timolol alone during a 6-month period preceding this trial. Intraocular pressure (IOP) was controlled with timolol alone in 135 of 183 eyes (74%) that completed the study. At the end of the trial 142 eyes (78%) showed an IOP of less than 22 mmHg. Other glaucoma medication had to be added to timolol treatment in 18% of ocular hypertensive and 35% of glaucomatous eyes because of IOP elevation. Elevation of IOP seemed to be due to worsening of glaucoma rather than to decreased efficacy of timolol. None of the ocular hypertensive patients developed visual field defects but in ten glaucomatous patients progression of existing visual field defects was observed in association with elevated IOP. Transient adverse effects were observed in 13% of cases, but timolol treatment had to be stopped in only five cases (4%) because of side effects.