LASIK术后的散光矢量分析

Vector analysis of astigmatism after LASIK

目的采用矢量法分析准分子激光原位角膜磨镶术(LASIK)术后散光产生的规律。方法选取249眼行LASIK矫正近视散光,分成低散光眼组(<-1.00 D)和相对高散光眼组(-1.00^-4.00 D),术后随访6个月。用标准分析方法对术前和术后的散光进行评估和统计。结果术后71.9%患者仍存在散光,低散光组散光下降了54.6%,相对高散光组下降了78.5%,二者差异有统计学意义(P<0.05)。轴向改变大部分>30°,手术矫正散光的量(SIRC)与目标矫正散光(IRC)呈正相关(r=0.93,P<0.01),术后残余散光的量(EV)与目标矫正散光(IRC)呈正相关(r=0.60,P<0.01)。术前散光度越高,手术矫正散光的轴向误差(EA)越小,数量误差的绝对值(EM)也越大。角度误差的绝对值(EA)绝大部分<15°,尤其是相对高散光眼组。结论为了减少术后散光,需提高术中矫正散光轴向的准确性。

Objective Laser-in situ keratomileusis（LASIK） is a primary method of correcting refractive error. The main complication following LASIK is astigmatism,which will influent the visual quality of patients. Present study was to investigate the rules of astigmatism after LASIK using vector analysis. Methods Total 249 myopic astigmatism eyes were treated with LASIK, including 133 eyes with astigmatism less than -1.0 D in low astigmatism group and 116 eyes with astigmatism -1.00 D - -4. 00 D in high astigmatism group. The following-up period was for 6 months. The astigmatism status was evaluated based on the standard of American National Standards Institute （ANSI）Z80. 11 Working Group on Laser Systems. This study followed the Declaration of Helsinki. Written informed consent was obtained from all the patients before and initiation of study. Results The astigmatism was still existed in 71.9% eyes in 6 months after surgery. The astigmatism degree was changed in 54.6% in low astigmatism group and 78.5% in relative high astigmatism group after surgery（ P 〈 0. 05 ）. The absolute value of surgical induced refractive correction（ I SIRC I） was positively correlated with the astigmatism before surgery（ r = 0.60 ,P 〈 0.01 ）. ｜ SIRC ｜ showed positive correlation with intended refractive correction（ ｜IRC｜ ） （ r = 0.93, P 〈 0.01 ）. Intended refractive correction ｜ EV ｜ presented the sifnificant correlation with ｜ IRC ｜ （ r = 0.60 ,P 〈 0.01 ）. Most of eyes with axis changed more than 30 degree. The more error of magnitude I EM I and smaller error of angle （ ｜ EA｜） were in high astigmatism group after surgery. Most eyes showed the ｜EA ｜ within 15 degrees. Conclusion The more attention should be paied to axis alignment of astigmatism in order to improve the postoperative astigmatism degree.