方法：回顾性临床病例研究。随机选择2009年40例80眼实施PRK治疗近视的患者作为常规组，2010年PRK术中应用0.2g/L MMC 20s的40例80眼作为MMC组。术后7d； 1，3，6，12mo观察裸眼视力、屈光状态以及角膜上皮愈合、发生糜烂、角膜干燥和haze情况，两组数据进行对比分析。

结果：术后12mo随访期间，两组裸眼视力、术后等效球镜、角膜上皮愈合及干眼情况差异无统计学意义。常规组有2眼，MMC组有9眼发生角膜糜烂伴丝状角膜炎，两组差异有统计学意义(Pearson χ²=4.783，P<0.05)。全部病例均治愈，没有复发病例。常规组、MMC组术后1，3，6，12mo haze的发生率分别为26%，6%，2%，0和44%，25%，10%，2%，术后1mo(Pearson χ²=5.385，P<0.05)、3mo(Pearson χ²=10.667，P=0.001)差异有统计学意义。

结论：PRK术中使用0.2g/L MMC可以减少术后haze的发生。MMC对PRK术中保留的角膜上皮的影响可能是术后角膜糜烂发生的原因之一，术中要避免接触到治疗区外保留的正常角膜上皮。

METHODS: In this retrospective study, 80 eyes of 40 patients were treated by PRK in 2009 as control group with the LaserSight SLX excimer laser. Eighty eyes of 40 patients were treated with 0.2g/L MMC 20s during PRK in 2010 as MMC group. Uncorrected visual acuity(UCVA), refraction, corneal epithelial healing, erosions, dry eyes, and haze were examined at 1 month, 3, 6 and 12 months postoperatively, and the 2 groups were compared and analyzed.

RESULTS: The differences between control and MMC group were not statistically significant in preoperative mean ages, UCVAs, best spectacle-corrected visual acuities, corneal depths, spherical equivalents(SEs), and laser ablation zones, depths, and times. During one year follow-up, the differences were also not in UCVAs, SEs, corneal epithelial healing, and dry eyes. But corneal erosions with filament keratitis were observed in 9 eyes in MMC group and 2 in control group, the difference was statistically significant(Pearson χ²=4.783, P=0.029). All the eyes were cured, and no recurrence occurred. The haze frequencies were 26%, 6%, 2%, 0 in MMC group at the 1 month, 3, 6, 12 months, and 44%, 25%, 10%, 2% in control group, respectively. The frequency differences were statistically significant at the 1 month(Pearson χ²=5.385, P=0.02)and 3(Pearson χ²=10.667, P= 0.001)months after surgery between the 2 groups.

CONCLUSION:Intraoperative MMC can reduce the haze frequency and grade after PRK for myopia. The effect of MMC on preserved corneal epithelium may be one of the reasons to happen corneal erosions after PRK. It is important to avoid 0.2g/L MMC exposure to corneal epithelium outside treatment zone.