Inhibitory effects of anti-glaucoma drugs on corneal epithelial migration in a rabbit organ culture system

Purpose: The possible effects of the anti-glaucoma drugs latanoprost, timolol maleate, and nipradilol on corneal epithelial wound healing were investigated in a rabbit organ culture system. Methods: Corneal blocks (approximately 2 x 4 mm) isolated from albino Japanese rabbits were cultured for 24 hours in medium containing various concentrations (0.01 to 10 mM) of latanoprost, timolol maleate, or nipradilol. The specimens were then fixed and embedded in paraffin, and thin sections were prepared. After the removal of paraffin, the sections were stained with hematoxylin-eosin and observed under a light microscope. Images were recorded digitally with a CCD camera, and the distance over which the epithelium had migrated down the sides of each block was calculated with a computer-assisted morphometric program. Results: Corneal epithelial migration was inhibited by each anti-glaucoma drug in a dose-dependent manner. The 50% inhibitory doses (ID) for latanoprost, timolol maleate, and nipradilol were 0.362, 0.585, and 4.89 mM, respectively. Relative to the concentrations present in commercially available eyedrops, ID50 corresponded to concentration ratios for timolol, nipradilol, and latanoprost were of 0.037, 0.64 and 3.1, respectively. Conclusions: The anti-glaucoma drugs examined inhibited corneal epithelial migration in a rabbit organ culture system. However, it is unlikely that the corneal surface would be exposed to these agents at inhibitory concentrations for a prolonged period in the normal clinical setting.