激光原位角膜磨镶术后角膜的共焦显微镜研究

Studies on corneal changes after laser in situ keratomileusis with confocal microscopy

目的通过共焦显微镜对角膜细胞水平的观察,了解激光原位角膜磨镶术(laser in situ keratomileusis,LASIK)后角膜伤口的愈合情况,角膜各层细胞的形态学变化及密度变化,角膜神经纤维的再生情况,以指导手术设计及术后的处理。方法通过Nidek公司的CONFOSCAN2.0共焦显微镜观察29例(58眼)接受LASIK手术的患者,将手术前后各时间段的角膜基质细胞密度、内皮细胞密度、角膜细胞激活范围作方差分析,两两比较有无差异;同时观察术后上皮下神经纤维的生长情况。结果LASIK后1周见多数患眼出现不同程度的前弹力层及浅基质层皱褶,角膜瓣板层切口前后见基质细胞激活,细胞稀疏,排列紊乱,边界不清,层间出现不同程度的高反光颗粒,随时间延长变少。角膜最浅层基质细胞密度较术前下降,直至术后6个月仍未恢复;最深层基质细胞密度与角膜内皮细胞密度较术前无显著性差异。基质激活范围与切削量无相关性(P>0.05),而与角膜瓣厚度呈负相关(r=-0.828,P<0.05),并且随时间延长激活范围减小(r=-0.580,P<0.01);术后第1周大部分未见上皮下神经纤维,少数出现短的无交联神经纤维,术后3个月约半数出现短的上皮下神经纤维,直至术后6个月才出现长的神经纤维,但密度及形态仍未恢复。结论LASIK手术导致角膜层间出现微小皱褶和碎屑,角膜基质细胞激活,范围随时间减小,并且角膜瓣越薄激活反应范围越广。调整手术相关参数(角膜瓣的厚度、大小、激光切削的深度和范围等)能减轻术后伤口的愈合反应和角膜神经的受损程度,减少术后干眼等并发症,促进术后角膜神经和基质细胞的早期恢复。

Objective To evaluate the response of corneal wound after laser in situ keratomileusis （LASIK） through observing by confocal microscope at cellular level, to determine the changes of corneal cell＇ s morphology and density, and to evaluate the regeneration of corneal nerve fiber for having instruction for treatment about LASIK. Methods Twenty-nine myopic patients（ 58 eyes） were selected and received confocal microscopy examinations to measure the flap thickness and stromal bed thickness. The correlation analysis between the thickness of flap and active zone was done. The keratocyte density of twenty-nine myopic patients were examined after LASIK using in vivo confocal microscopy for measurement of keratocyte density, endothelial density and active keratocyte zones. Preoperative data and postoperative data were compared. The changes of morphology of keratocyte and nerve fiber by confocal microscopy were evaluated. Results Microfolds were found at Bowman＇ s layer and anterior stromal layer. Stromal keratocyte were activated and sparse,arrangement was disorder, with obscure boundary. High refractive particles were found at the interface and decrease with time. The density of keratocyte in the first stromal layer decrease since one week after operation and did not recover until six months after surgery. The changes of the density of keratocyte in the most posterior stromal layer and endothelium was not found. Activated zone and flap thickness showed negative correlation. The density in the first stromal layer and the most posterior stromal laye did not change. Activated zone have no correlation with ablation（ P 〉 0.05 ）. Activated zone and flap thickness showed negative correlation（ r = - 0. 828, P 〈 0.05 ） and decrease with time （ r = - 0.58 ,P 〈 0.01 ）. The changes of morphology of keratocyte in the most posterior stromal layer and endothelium was not found. Nerve fiber was not found in one week after surgery except that a few appears short nerve fiber. Long nerve fiber can not be found until six months after surgery, but density and morphology of nerve fiber still did not recover. Conclusions Microfolds, high refractive particles and activated keratocyte were found after sugery. The zone of activated keratocyte decreased with time. The thinner the corneal flap,the wider the activated zone were Adjusting parameter of operation （ flap thickness, diameter, the depth of ablation, the diameter of ablation） can decrease the healing reaction and lessen the damage to corneal nerve, decrease the incidence of complication like dry eye;reasonable application of medication can ease the symptoms of dry eye, accelerate the recovery of the corneal nerve and keratocytes.