Timolol inhibits corneal epithelial wound healing in rabbits and monkeys

T. M. Nork, F. J. Holly, J. Hayes, T. Wentlandt and D. W. Lamberts

To determine the effect of timolol maleate on corneal epithelial wound closure, 6.4-mm (diameter) epithelial defects were created chemically in five experiments. In rabbits, wound closure was not significantly altered by the administration of 0.5% Timoptic (a commercially prepared timolol maleate solution) every eight hours, but it was inhibited during the first 15 hours of healing when a 4% solution was applied every two hours. Monkeys received a 5% solution every 12 hours and were divided into treated and control groups. Two phases of wound healing were apparent: a rapid initial phase and a slower final phase. Wound closure was inhibited in treated eyes during the initial rapid phase. This experiment repeated on the same monkeys, but with the control and treated animals switched, yielded the same result. Another experiment, with the fellow eye of the monkey used as a control, showed no significant difference in wound closure.