Growth factor expression in corneal wound healing after excimer laser keratectomy

Purpose. To develop a rabbit model of reproducible corneal haze after excim er laser keratectomy and to characterize expression of transforming growth factor beta (TGF beta) and basic fibroblast growth factor (bFGF) in rabbit corneas during haze formation. Methods. Seven rabbits underwent a 100 mu m deep phototherapeutic keratectomy (PTK) in one eye and a 15-mu m shallow PT K in the contralateral eye. Corneal haze was compared at 1-20 weeks after s urgery. Subsequently, 16 rabbits underwent 100-mu m PTK in one eye and 15-m u m PTK in the contralateral eye. Four rabbits were killed at 1, 2, 3, and 4 weeks, respectively, after surgery. Immunohistochemistry was performed on the corneas to localize the expression of TGF beta and bFGF. Control subje cts were rabbits that underwent either epithelial debridement alone or no s urgery. Results A 100-mu m PTK resulted in significantly more corneal haze than a 15-mu m PTK at every postoperative examination (p < 0.05). Both TGF beta and bFGF were expressed in the scars at 1-4 weeks after deep and shall ow excimer ablations. bFGF was expressed in the keratocytes of both treated and control corneas. Minimal TGF beta was detected in the keratocytes of t he control corneas, whereas prominent TGF beta expression was noted in the keratocyte-like cells adjacent to the postkeratectomy scars. Conclusions. T he 100-mu m PTK ablation resulted in significantly more corneal scarring th an the 15-mu m PTK ablation. Even though there was no immunohistochemical d ifference in the pattern of TGF beta and bFGF expression after deep and sha llow ablations, there was an association between the expression of the grow th factors and corneal scarring after excimer laser keratectomy.