Mitomycin C Reduces Corneal Light Scattering After Excimer Keratectomy

PURPOSE.To evaluate the effect of intraoperative mitomycin C (MMC) on corneal light scattering after excimer laser keratectomy. METHODS.Phototherapeutic keratectomy (PTK) was performed in 24 rabbit eyes. After 40-μm epithelial ablation, animals were divided into three groups. In group 1, filter paper discs soaked with MMC (group 1A, 0.5 mg/mL; group 1B, 0.25 mg/ml) were applied for 1 minute. In group 2, annular filter papers soaked with MMC (group 2A, 0.5 mg/mL; group 2B, 0.25 mg/mL) were applied for 1 minute. Controls received vehicle only (group 3). Six-millimeter diameter 100-μm deep PTK was performed. Corneal light scattering was measured weekly from 1 to 6 weeks, at 10 weeks, and at 8 and 13 months using a scatterometer. A corneal light scattering index (SI) ranging from 0 to 10 was calculated; SI of 1 represents normal scattering. RESULTS.A statistically significant decrease in mean SI was noted in group 2A (annular MMC 0.5 mg/mL;p < 0.05) as compared with the control group at 2 weeks. At 10 weeks, SI approached baseline levels in group 2 and the control group but showed significant increase in group 1 (MMC disc;p < 0.05). At 8 and 13 months, SI showed no statistical differences between groups. CONCLUSIONS.Controlled application of 0.5 mg/mL MMC in the corneal midperiphery transiently reduces corneal light scattering after excimer keratectomy in this rabbit model.