Effect of alpha- and beta-receptor active drugs on corneal thickness

Phenylephrine (10 mg/ml), phentolamine (10 mg/ml), isoprenaline (0.5 mg/ml) and timolol (5 mg/ml) were applied topically to one eye of volunteers with normal corneas, the other eye serving as a control. One drop of each drug was given twice a day for 3 or 4 days. Timolol was found to increase corneal thickness in both the medicated and the control eye. A significantly greater effect was noted on the eye receiving the drug directly. When isoprenaline was given for 3 days, a slight significant decrease in corneal thickness was found in both the medicated and the control eye, with the two eyes exhibiting a similar CCT change. The present results are suggestive of endothelial beta-receptor importance in the regulation of corneal thickness.