Corneal wound healing in monkeys 18 months after excimer laser photorefractive keratectomy

Excimer laser keratomileusis (photorefractive keratectomy, direct corneal ablation) for myopic corrections of 2.00 diopters (n = 1), 4.00 D (n = 4), and 8.00 D (n = 3) was performed on eight corneas of four Rhesus monkeys. All animals were followed for 18 months. The ablations healed normally and no epithelial erosions occurred. Serial slit-lamp microscope examinations revealed that a variable amount of corneal haze developed in all animals; this haze progressively faded during the follow-up period. Histopathology revealed an epithelium of normal thickness, basement membrane abnormalities, increased number and activity of stromal keratocytes, and a variable amount of newly secreted extracellular matrix in the anterior stroma. These findings suggest that excimer laser keratomileusis induces a mild wound healing response in the anterior cornea which displays considerable individual variability and persists up to 18 months.