留瓣与弃瓣机械法准分子激光角膜上皮瓣下磨镶术的临床效果及角膜形态比较

Comparison of effectiveness and corneal morphology between on-flap Epi-LASIK and off-flap Epi-LASIK

目的探讨机械法准分子激光角膜上皮瓣下磨镶术(Epi-LASIK)留瓣与弃瓣术后的临床效果及角膜形态改变。方法采用随机数字表法对接受Epi-LASIK的患者33例66眼随机进行留瓣和弃瓣处理,分为留瓣组和弃瓣组,每组33眼。术后随访4个月,检查裸眼视力、屈光度、角膜上皮下雾状混浊(haze)、角膜前表面最佳拟合球面半径、角膜前表面高度值和角膜3mm、5mm不规则度及散光度。结果术后裸眼视力留瓣组为1.42±0.21,弃瓣组为1.40±0.21,均较术前的0.13±0.08、0.13±0.13明显提高(t=-35.577、t=-29.027,P<0.01);haze分别为0.17±0.12和0.14±0.93;2组角膜前表面最佳拟合球面半径分别为(8.21±0.22)mm和(8.21±0.23)mm,均较术前的(8.01±0.19)mm和(8.02±0.20)mm明显增加(t=-12.212、t=-12.073,P<0.01);角膜前表面高度值分别为(-0.00±0.02)mm和(-0.00±0.01)mm,均明显低于术前的(0.01±0.00)mm和(0.01±0.00)mm(t=3.845、t=8.691,P<0.01);角膜3mm、5mm散光值留瓣组为(0.71±0.36)D和(1.27±1.04)D,弃瓣组为(0.80±0.42)D和(1.38±0.98)D,5mm散光值均较3mm散光值高(t=-3.275,-3.964;P<0.05);2组角膜3mm不规则度为(2.37±0.63)D和(2.45±0.73)D,差异无统计学意义(P>0.05)。5mm不规则度分别为(3.22±0.93)D和(3.47±1.40)D,较术前均明显增大(P<0.01),且5mm不规则度较3mm不规则度大(t=-6.550、t=-4.793;P<0.01)。术后4个月2组间裸眼视力、屈光度、haze等级、角膜前表面最佳拟合球面半径、角膜前表面高度值、角膜3mm及5mm散光值、角膜3mm及5mm不规则度比较差异均无统计学意义(P>0.05)。结论留瓣与弃瓣Epi-LASIK均能显著提高术后裸眼视力,降低haze的发生及角膜形态的改变,安全有效。

Background Epithelial flap plays an important role in the cornea wound healing response after laser in situ keratomileusis（LASIK）,therefore,the corneal morphology study after on-flap Epi-LASIK and off-flap Epi-LASIK is being concerned.ObjectiveThe aim of this study was to evaluate the outcome and corneal shape changes after on-flap Epi-LASIK and off-flap Epi-LASIK.MethodsA randomized prospective study of 33 consecutive cases（66 eyes）were conducted.All patients were randomly assigned to on-flap Epi-LASIK（on-flap group）or off-flap Epi-LASIK（off-flap group）.Uncorrect visual acuity,corneal anterior surface best fit spherical radius,corneal anterior surface elevation,3mm and 5mm irregularity indexes were recorded preoperatively and postoperatively.Haze and 3mm and 5mm astigmatism were inspected postoperatively.The differences in these values were compared between the two groups.The changes of these values in each group before and 4 months after surgery were analyzed.This clinical trial followed the Declaration of Helsinki and Human Research Ethic Committee of this hospital approved this study.Written informed consent was obtained before surgery in all patients.ResultsThe postoperative mean uncorrect visual acuity in the eyes from on-flap Epi-LASIK group and off-flap Epi-LASIK group were（1.42±0.21）and（1.40±0.21）respectively,indicating a significant elevation in comparison with those of preoperation（0.13±0.08 vs 0.13±0.13）（t=-35.577,t=-29.027,P0.01）.The grading of haze was（0.17±0.12）in on-flap group and（0.14±0.93）in off-flap group respectively.The mean corneal anterior surface radius in postoperation was（8.21±0.22）mm in on-flap group and（8.21±0.23）mm in off-flap group,showing a statistical increase in comparison with preoperation（t=-12.212,t=-12.073,P0.01）.The mean corneal anterior elevation decreased from（0.01±0.00）to（-0.00±0.02）in the on-flap group and from（0.01±0.00）to（-0.00±0.01）in the off-flap group after surgery（t=3.845,t= 8.691,P0.01）.The irregularity indexes of 3mm was（2.37±0.63）D in the on-flap group and（2.45±0.73）D in the off-flap group without significant difference（P0.05）;and that of 5mm was（3.22±0.93）D in the on-flap group and（3.47±1.40）D in off-flap group with a evident difference（P0.01）.The irreguarity index was obviously higher in 5 mm area than that of 3mm area（P0.01）.No significant differences were found in all the factors mentioned above at 4 months after surgery between these two groups（P0.05）.ConclusionBoth on-flap and off-flap Epi-LASIK can improve the uncorrect visual acuity,decrease haze and alter the corneal shape.