Effect of timolol on the permeability of corneal endothelium.

The effect of short-term administration of timolol on the permeability of the corneal endothelium to fluorescein was measured in normal subjects (single drop) and in a small group of glaucoma patients (one week's treatment). No effect on the endothelium was found in the normal eyes. In the glaucomatous eyes, endothelial permeability was higher than normal when measured after one week without topical medications and normal when measured after one week on timolol treatment. No evidence was found that short-term administration of this drug disturbs the barrier function of the endothelium.