Effect of chronically administered timolol on aqueous humor flow in patients with glaucoma

A prospective analysis of the effect of chronically administered timolol on the rate of aqueous humor flow through the anterior chamber was performed in 15 eyes of 13 subjects with chronic open-angle glaucoma. After one week's treatment, the flow of each treated eye was lower than it had been prior to treatment. After one year's treatment, the flow of 13 of 15 treated eyes was lower than it had been prior to treatment. However, the flow was higher in 12 of 15 eyes after a year's treatment than it had been after a week's treatment. These data suggest that the ciliary body or other structures in the eye must partly adapt to the chronic administration of this drug. The mechanism of the adaptation is unknown.