Epithelial Hyperplasia of Rabbit after Experimental PRK

Objective To investigate the proliferative changes in corneal epithelium after photorefractive keratectomy (PRK). Methods PRK was performed on both eyes of 21 New Zealand white rabbits. The attempted corrections were -5.0 diopters for the right eye and -15.0 diopters for the left. The eyes were enucleated respectively at 1,3 days, 1 and 2 weeks,and 1,3 and 6 months after surgery.The thickness of epithelium was measured under light microscope. The positive cell rate of proliferating cell nuclear antigen (PCNA) in the healing epithelium was also examined. Results The epithelial thickness increased from 2 weeks postoperativey tile 6 months, especially for the left eye. The PCNA positive cells in the regenerating basal cell layer became more than that of controls from the 3rd day, and didn′t return to normal until 1 month after surgery for the right eye and 3 months for the left. Conclusions The corneal epithelium shows proliferating disturbance for several weeks after PRK, especially in the deeper ablated corneas. The proliferating activity enhancement may be the most important reason for the epithelium hyperplasia after PRK.