AIM: To study the effect and safety of applying mitomycin C(MMC)in laser subepithelion keratomileusis(LASEK)surgery of middle or high myopia to prevent the formation of haze under corneal epithelium.

METHODS: Totally 120 patients(240 eyes)for LASEK surgery were selected randomly, the right eyes were set as test group, and the left eyes as control group. The eyes in control group underwent general LASEK, while for the test group, a filter paper with 0.2g/L MMC solution was covered on the corneal stroma bed after the laser ablation. The postoperative symptom, epithelial flap, recorrected visual acuity, haze formation were investigated.

RESULTS: There was no statistical difference of ocular irritation symptom and corneal epithelium healing time between the two groups. For the test group the grade 0 haze was found in 105 eyes(87.5%)by 1 month, in 80 eyes(66.7%)by 3 months, in 96 eyes(80.0%)by 6 months, while for the control group in 62 eyes(51.7%)by 1 month, in 39 eyes(32.5%)by 3 months, in 68 eyes(56.7%)by 6 months, there was statistically significance. Uncorrected visions were more than 1.0 in 91 eyes(75.8%)for the test group, while in 51 eyes(42.5%)for the control group in 6 months after operation, there was statistically significance(P<0.05).

CONCLUSION: The application of 0.2g/L MMC during LASEK for treatment of middle or high myopia was a safe and effective treatment. It could reduce the formation of haze.