THE EFFECT OF TOPICAL PARASYMPATHOMIMETICS ON CORNEAL EPITHELIAL HEALING IN RABBITS

Corneal wound healing is an important process that involves interactio n between the different corneal cell layers, growth factors, and envir onmental conditions. More powerful therapies for the treatment of dela yed epithelial wound healing are still being proposed. The objective o f this study is to investigate the effects of the direct-acting parasy mpathomimetic agents on the healing process of corneal epithelium in r abbits. The corneal epithelial defects, 10 mm in diameter, were create d in 32 eyes of 16 island rabbits by combination of chemical debrideme nt using n-heptanol and mechanical scraping. Animals were randomly div ided into four groups. Groups 1, 2 and 3 were treatment groups; each g roup consisted of four rabbits (8 eyes). The animals in these groups w ere treated with topical 1% acetylcholine (ACh), 2% pilocarpine, and 0 .75% carbachol drops respectively. In group 4, four rabbits (8 eyes) w ere used as control group and left for spontaneous healing. The length acid area of the defect were measured at days 3,6,9,12,15,18 and 22 a fter wounding. Areas of the photographically documented fluorescein-st ained defects were measured by planimetry. All eyes in the treatment g roups reepithelialized completely. The duration for reepithelializatio n in Groups 1 and 2 was 12 days, and 18 days for Group 3. In the contr ol group reepithelialization occurred within 22 days. The healing rate s of corneal epithelium were statistically significantly faster in all treatment groups as compared with the control group at all times (p=0 .0001 to 0.0.0279). Although the rates of wound healing varied, all of the parasympathomimetics used in the present study were found to faci litate wound healing. Our results indicate that direct-acting choliner gic agents, especially ACh and pilocarpine, may have an important ther apeutic role in the treatment of severe corneal epithelial injury.