Effect of cysteine in transgenic mice on healing of corneal epithelium after excimer laser photoablation.

PURPOSE: To evaluate the role of prepared cysteine per os in corneal epithelial healing in transgenic mice (B6(A)-Rpe65rd12/J) after excimer laser photoablation. MATERIALS AND METHODS: In our prospective case series, 60 eyes of 30 mice had uneventful bilateral excimer laser photoablation. A first group, composed of 15 mice, received standard topical post-operative therapy with tobramycin, diclofenac and dexamethasone eyedrops, plus cysteine 5 mg 5 microg/10 microl phosphate-buffered saline (3 times a day for 1 week) per os or until corneal re-epithelialization was complete. The control group of 15 mice received standard post-operative therapy plus placebos. The mice were monitored daily, commencing the day after surgery, for 7 days to evaluate the corneal re-epithelialization rate using a video slit-lamp camera with a cobalt blue light. The mean diameters of corneal wounds were measured. Videotaped images were recorded and analysed by computer planimetry. RESULTS: All the eyes of the mice treated with cysteine healed completely by day 5 after surgery, with a mean re-epithelialization time of 92 +/- 10 h (SD); the mean re-epithelialization time was 125 +/- 8 h in eyes that received the placebo. There were no statistically significant differences between the 2 groups in corneal haze presentation during follow-up, perhaps because the time period was too brief (7 days). However, corneal clarity in the study group was greater than in the control group, as shown on slit-lamp biomicroscopy. No side effects or toxic effects were documented. CONCLUSIONS: These data suggest that cysteine significantly accelerates epithelial healing after excimer photoablation. A further clinical study should be performed to confirm the results obtained in this study, and the long-term efficacy of cysteine in preventing corneal haze.

Effect of cytochrome c peroxidase on the corneal epithelial healing process after excimer laser photo-ablation in transgenic mice.

AIM: To evaluate the role of commercially prepared cytochrome c peroxidase eye drops in corneal epithelial healing of transgenic B6(A)-Rpe65rd12/J mice after excimer laser photo-ablation. MATERIALS AND METHODS: In our prospective animal series, 72 eyes of 36 mice had uneventful bilateral excimer laser photo-ablation. In each mouse, one eye received standard topical postoperative therapy with tobramycin, diclofenac, and dexamethasone eye drops plus cytochrome c peroxidase eye drops (two drops three times a day for 1 week or until corneal re-epithelialization was complete, corresponding to 15,000 IU/day). The fellow eye served as the control and received standard postoperative therapy plus placebo. The mice were monitored daily, commencing on the day after surgery, for 7 days to evaluate the corneal re-epithelialization rate using a video slit lamp camera with cobalt blue light. The mean diameter of the corneal wounds was measured. Videotaped images were recorded and analyzed by computer planimetry. RESULTS: All eyes treated with cytochrome c peroxidase eye drops healed completely before day 5 after surgery, with a mean re-epithelialization time of 92 +/- (SD) 10 h; the mean re-epithelialization time was 121 +/- 8 h in the eyes receiving placebo (p < 0.05). There were no statistically significant differences between the two groups in corneal haze presentation during the follow-up period (p = 0.70), perhaps because the observation period was too short (7 days). However, the corneal clarity, on slit lamp biomicroscopy, in the study group was higher than that in the control group. No side effects or toxic effects were observed. CONCLUSIONS: These data suggest that cytochrome c peroxidase significantly accelerates epithelial healing after phototherapeutic keratectomy. Further clinical studies should be performed to prove the results obtained in this study and the long-term efficacy of cytochrome c peroxidase to prevent corneal haze.