CORNEAL WOUND-HEALING MODULATION USING BASIC FIBROBLAST GROWTH-FACTORAFTER EXCIMER-LASER PHOTOREFRACTIVE KERATECTOMY

Photorefractive keratectomy with the 193-nm excimer laser is one of th e most promising innovations in refractive surgery. However, routine c linical application is hindered by two main obstacles, i.e., postopera tive subepithelial opacity and possible regression of the refractive r esult. Because we have previously demonstrated beneficial effects of b asic fibroblast growth factor (bFGF) on corneal epithelial healing in different in vivo models, we investigated the influence on both epithe lial and stromal healing of topical bFGF after excimer laser keratomil eusis in a rabbit model. After 7-mm circular deepithelialization, the eyes of 24 New Zealand White rabbits received identical deep stromal l aser ablations (depth 50 mu m, 6 D, diameter 5 mm) and were randomly a ssigned to one of four treatment groups [control (phosphate-buffered s aline, PBS), bFGF 10 mu g/application, dexamethasone 0,1%, bFGF + dexa methasone, n = 12 eyes/group]. All treatments were administered four t imes daily-bFGF until complete epithelial healing, dexamethasone and P BS until 3 months postsurgery. Wound surface regression on time was de termined by means of computer-assisted image analysis of fluorescein-s tained corneas. Corneal opacity was observed biomicroscopically acid g raded using a previously established scoring system. After bFGF applic ation for 2-3 days only, a highly significant acceleration in epitheli al wound healing speed was found compared with the rate of the other t hree treatment groups (p < 0.001). A combined therapy (bFGF + steroid) had no effect on the healing rate, Compared with control values, mean scores for subepithelial haze in the other groups were found to be ne arly 50% lower during the first 2 postoperative months. No significant difference could be seen between eyes that received bFGF, dexamethaso ne, or bFGF + steroid. These results demonstrate for the first time th e efficiency of a growth factor in modulating the wound healing respon se after excimer laser photoablation. Also with regard to possible adv erse reactions, a short-term and low-dose bFGF application seems advan tageous over a continuous treatment with corticosteroid drugs.