Persistent corneal haze after excimer laser photokeratectomy in plasminogen-deficient mice

PURPOSE. Excimer laser photorefractive keratectomy creates a nonvascular wo und of the cornea. Fibrin deposition and resolution after excimer laser pho tokeratectomy were investigated in relation to corneal repair and restorati on of clarity in mice with a genetic deficiency of plasminogen. METHODS. A Summit Apex Laser (Summit, Waltham, MA) was used to perform 2-mm , 175-pulse, transepithelial photoablations that resulted in deep stromal k eratectomies. Photokeratectomy was performed on the corneas of plasminogen- deficient (Plg(-/-)) mice and Littermate control animals. Eyes were examine d for re-epithelialization and clarity throughout the 21-day observational period. Histologic sections were taken during the observational period and fibrin(ogen) was detected immunohistochemically. RESULTS. Re-epithelialization was rapid and complete within 3 days in both control and Plg(-/-) animals. Exuberant corneal fibrin(ogen) deposition was noted in Plg(-/-) mice and sparse fibrin(ogen) deposition in control mice on days 1 and 3 after injury. Fibrin(ogen) deposits resolved in control mic e but persisted in Plg(-/-) mice (74% of eyes at 21 days; P < 0.004). Corne al opacification, scarring, and the presence of anterior chamber fibrin(oge n) occurred in plasminogen-deficient mice but not in control mice. CONCLUSIONS. Fibrin(ogen) deposition occurs during corneal wound repair aft er photokeratectomy. Impaired fibrinolysis in Plg(-/-) mice caused persiste nt stromal fibrin deposits that correlated with the development of corneal opacity.