Effect of topical beta blockers on corneal epithelial wound healing in the rabbit

Topical beta adrenergic receptor blocking agents (beta blockers) are among the most frequently prescribed ophthalmic drugs. It has been suggested that some of these agents have a toxic effect on the corneal epithelium. In the present study, four beta blockers in common therapeutic concentrations, as well as their vehicles, were applied to rabbit corneas that had undergone mechanical removal of epithelium from a 6 mm diameter corneal wound. The tested drugs (0.25% timolol, 0.25% levobunolol, 0.25% betaxolol, and 0.3% metipranolol) were found significantly to accelerate wound closure, compared with saline treatment in controls. Eyes treated with two of the vehicles (betaxolol vehicle and metipranolol vehicle) also demonstrated more rapid healing than controls, but the magnitude of the effect was not as great as that seen with the drugs. Only the beta blockers were responsible for wound closure before 60 hours, whereas the saline treated controls and vehicle treated eyes required longer times for wound closure. In this model of wound healing, beta blockers appear to have no deleterious effect on corneal epithelial wound healing.