矢量法分析LASEK和LASIK矫正高度散光的疗效

Power vector analysis of the outcomes of laser subepithelial keratomileusis and laser in situ keratomileusis for high myopia astigmatism

目的应用Thibos矢量法比较准分子激光上皮瓣下角膜磨镶术(laser subepithelial keratomileus-is,LASEK)和准分子激光原位角膜磨镶术(laser in situ keratomileusis,LASIK)矫正高度散光(≥-2.75D)的疗效。方法LASEK59例(59眼),LASIK37例(37眼)。分析两组患者术前和术后裸眼视力(uncorrected visualacuity,UCVA)、最佳矫正视力(best corrected visual acuity,BCVA)、屈光度(S球镜,C柱镜,M等效球镜)和模糊指数B的差别。结果除LASIK组BCVA外,所有患者术前和术后UCVA、BCVA、S、M、C、B差异均有统计学意义。术后两组间S、C、M、B差异均无统计学意义,BCVA较术前无一例发生下降2行。结论LASEK和LASIK手术方式均安全、手术效果可靠,是治疗高度散光的有效方法。Thibos矢量分析能够全面地描述眼屈光异常和屈光手术疗效。

Objective To compare the clinical outcomes of laser subepithelial keratomileusis （LASEK） with laser in situ keratomileusis（LASIK） for the correction of high myopic astigmatism using the power vector method of Thibos. Methods This analysis comprised 59 eyes that had LASEK and 37 eyes that had LASIK for high myopia astigmatism （cylinder ≥-2.75 D）. Postoperative uncorrected visual acuity （UCVA）, best corrected visual acuity（ BCVA）, manifest refractive errors and power vector （B） were compared with preoperative respectively. Manifest refractive errors were expressed as a spherical lens of power M and a Jackson crossed cylinder. The pythagorean length of the power vector （B） was a measure of overall blurring strength of a spherocylindrical lens or refractive error. Results UCVA and BCVA were significantly better after operation in both groups, whereas BCVA had no significant difference in LASIK eyes. Postoperative refractive error and blur strength（B） were significantly lower in both groups. The postoperative vision, refractive error and blur strength（B） were similar in both groups. No eye lost more than 2 lines of BCVA in both groups. Power vector analysis found that both LASEK and LASIK were successful in achieving the astigmatic surgical correction at the last postoperative visit. Conclusions LASEK and LASIK are both effective and safe procedure for the treatment of high myopic astigmatism. The power vector approach creates a natural link from current clinical practice to an optical theory, powerful enough to provide a comprehensive description of all the refractive imperfections of an eye.