方法：收集我院行TransPRK手术治疗中高度近视的患者61例，随机分为试验组(0.1g/L MMC放置40s)21例和对照组(0.2g/L MMC放置40s)40例。所有患者随访3mo，观察的指标包括术后上皮愈合时间、术后第1d疼痛评价、最佳矫正视力、屈光度、haze情况及角膜光密度的变化。

结果：术后0.1g/L组上皮愈合时间为3.86±1.11d，0.2g/L组为4.23±1.27d，术后第1d疼痛评分0.1g/L组为2.01±0.58分，0.2g/L组为1.79±0.7分，两组间差异均无统计学意义(P=0.667、0.582)； 0.1g/L组术后1、3mo等效球镜度分别为0.28±0.25、0.05±0.23D，0.2g/L组分别为-0.13±0.17、0.07±0.22D； 两组之间比较，差异无统计学意义(P=0.178、0.490)。视力方面，0.2g/L组术后1mo视力稍下降，到3mo时恢复至术前水平，差异有统计学意义(F=15.847，P<0.001)，0.1g/L组虽然也表现出这种变化趋势，但无统计学差异(F=3.038，P=0.093)，而组间比较无统计学差异(P>0.05)。术后两组间1、3mo haze情况未见统计学差异(z=-0.709，P=0.479； z=-0.478，P=0.633)。两组术后1mo角膜光密度均较术前增加，至术后3mo恢复到术前水平，差异有统计学意义(0.1g/L组：F=27.399，P=0.001； 0.2g/L组：F=8.313，P=0.001)，组间对比无统计学差异(P>0.05)。

结论：TransPRK治疗中高度近视术中使用低浓度MMC预防haze是安全、有效的，其疗效与常规用量(0.2g/L)相当，而且视力更早趋于稳定； 判断角膜透明性时，光密度测量可以作为裂隙灯检查外的一种辅助手段。

METHODS: Sixty-one patients underwent TransPRK with moderate and high myopia. Eyes were divided into research group(0.1g/L MMC for 40s)and control group(0.2g/L MMC for 40s)randomly. There were 21 patients in research group and 40 patients in control group. Cornea epithelial healing time, pain score, visual acuity, manifest refraction, haze and cornea density were analyzed.

RESULTS: The epithelial healing time(0.1g/L group: 3.86±1.11d, 0.2g/L group: 4.23±1.27d)and pain score(0.1g/L group: 2.01±0.58, 0.2g/L group: 1.79±0.7)were no significant difference between two groups(P=0.667, P=0.582). It was similar in spherical equivalent at 1mo and 3mo post-operation(0.1g/L group: 0.28±0.25, 0.05±0.23D; 0.2g/L group: -0.13±0.17, 0.07±0.22D; P=0.178, P=0.490). The BCVA of control group decreased at 1mo and improved to the same level as pre-operation at 3mo(F=15.847, P<0.001); 0.1g/L group showed the same trend, but the changes were no significant difference(F=3.038, P=0.093). There were also no significant difference in Haze between two groups post-operation(z=-0.709, P=0.479; z=-0.478, P=0.633).The change of cornea density was matched with the BCVA(0.1g/L group F=27.399, P=0.001; 0.2g/L group F=8.313, P=0.001)and it was similar between two groups.

CONCLUSION: The using of low dose MMC to prevent haze in TransPRK with moderate and high myopia is safe and effective. It is therapeutic equivalence to regular dose(0.2g/L). Besides the slit lamp, we can use the corneal density to measure the corneal transparency.