方法：选择LASEK联合MMC治疗的超高度近视患者182例364眼，等效球镜-9.0～-10.25D，随机分为四组，Ⅰ组术中MMC应用时间为10s，Ⅱ组MMC应用时间为25s，Ⅲ组为40s，Ⅳ组为55s。术后随访6mo，观察各组术眼的疗效和安全性，随访指标包括裸眼视力(uncorrected visual acuity，UCVA)、残留屈光度、角膜上皮下雾状混浊(haze)的发生率、角膜上皮愈合时间以及角膜内皮细胞的密度和变异系数。

结果：术后随访6mo，Ⅱ组、Ⅲ组、Ⅳ组患者UCVA≥0.8者分别为94.0%、92.3%、93.8%，明显好于Ⅰ组(76.3%)，差异有显著统计学意义(χ²=19.610，P=0.000)； Ⅱ组、Ⅲ组、Ⅳ组患者残留屈光度位于±0.5D以内者分别为95.2%、93.3%、92.7%，明显高于Ⅰ组(78.8%)，差异有显著统计学意义(χ²=16.329，P=0.001)。术后6mo时Ⅰ组haze的发生率高于其余三组，差异有显著统计学意义(H_c=50.110，P=0.000)； 各组术后角膜上皮细胞愈合时间之间比较，差异无统计学差异(χ²=11.611，P>0.05)； 术后各组角膜内皮细胞密度分别为3 071.3±284.4个/mm²(Ⅰ组)、3 105.6±337.8个/mm²(Ⅱ组)、2 986.3±304.1个/mm²(Ⅲ组)、3 088.7±372.5个/mm²(Ⅳ组)，与术前比较差异无统计学意义(P>0.05)； 变异系数分别为24.72±6.52(Ⅰ组)、22.93±6.74(Ⅱ组)、24.38±6.63(Ⅲ组)、23.14±7.22(Ⅳ组)，与术前比较无统计学差异(P>0.05)。

结论：LASEK联合MMC治疗超高度近视具有良好的效果和安全性，0.2g/L MMC作用25s的应用时间能有效抑制haze的形成，又能减少MMC潜在不良反应的发生率。

METHODS: LASEK with 0.02% MMC was performed in 364 eyes of 182 patients with extreme high myopia and spherical equivalent was -9.0 to -10.25 D. All the patients were divided into four groups according to the applying time of MMC. The time in Group Ⅰ was 10s, in Group Ⅱ was 25s, in Group Ⅲ was 40s and 55s in Group IV. Uncorrected visual acuity(UCVA), residual refraction, Haze, healing time of corneal epithelium, density and variant index of corneal endothelium was examined in these patients and follow-up 6mo.

RESULTS: At 6mo after surgery, 76.3%, 94.0%, 92.3% and 93.8% of the patients in Group Ⅰ, GroupⅡ, Group Ⅲ and Group IV respectively achieved the UCVA better than 15/20. There was significant difference of UCVA between Group Ⅰ and the other three groups(χ²=19.610, P=0.000). Proportion of the residual refraction between ±0.5D in Group Ⅰ(78.8%)was lower than other groups(95.2% in Group Ⅱ, 93.3% in Group Ⅲ, and 92.7% in Group Ⅳ)at 6mo and there was significant difference(χ²=16.329, P=0.001). Group Ⅰ had more Haze statistically than the other three groups at 6mo postoperatively(H_c=50.110, P=0.000). The healing time of cornea epithelium seem to be no statistically difference between each group at 6mo(χ²=11.611, P>0.05). MMC had no influence on the density of corneal endothelium in each group postoperatively(P>0.05), there were 3 071.3±284.4 cells/mm² in Group I, 3 105.6±337.8 cells/mm² in Group Ⅱ, 2 986.3±304.1cells/mm² in Group Ⅲ and 3 088.7±372.5 cells/mm² in Group IV respectively. The variant index of corneal endothelium calculated in each group at 6mo after surgery was 24.72±6.52, 22.93±6.74, 24.38±6.63 and 23.14±7.22 repectively, compare with that preoperatively there were no statistically differences(P>0.05).

CONCLUSION: For extreme high myopia LASEK with 0.02% MMC is effective and safe. The MMC applying time of 25s in LASEK can effectively reduce Haze after surgery and decrease potential complications.