首页 > 文献资料
-
角膜屈光手术后的高阶像差与视觉质量
准分子激光角膜屈光手术(Excimer laser corneal refractive surgery)作为目前屈光不正的主要矫正方法之一,全球每年有数百万人接受此类手术[1],在我国每年也有几十万的治疗患者.过去十余年的大量临床实践表明,由于技术和设备的进步,病理性并发症趋于减少,但视觉功能方面的问题仍未完全解决,部分患者手术后出现光晕、眩光、单眼复视、夜间视力下降等光学并发症[2-3].许多研究显示,手术后高阶像差(以球差和彗差为主)的增加是其产生的重要因素[4-5].因此,掌握手术后高阶像差产生的原因并对其进行有效控制和预防,将对减少角膜屈光手术的光学并发症、提高手术后视觉质量具有十分重要的作用.
-
角膜屈光手术后人工晶状体度数计算
自上世纪80年代以来,角膜屈光手术在矫正屈光不正方面取得了很大进展,首先是角膜放射状切开手术治疗了大量的近视眼患者,90年代后逐渐被准分子激光手术(photorefrective keratectomy,PRK)和准分子激光原位角膜磨镶术(laser in situ keratomileusis,LASIK)所取代,随着年龄的增加这些患者已逐步发生白内障并且需要手术治疗.这些白内障手术操作与普通白内障手术相比并无多大区别,但人工晶状体的度数计算却是个难题.近视眼尤其是高度近视的白内障患者由于眼球解剖结构异常,人工晶状体(Intra OcularLens,IOL)度数计算误差就较大,角膜屈光手术改变了角膜的解剖结构,按曲率计或角膜地形图测定角膜屈光度、眼轴长度以及传统人工晶状体公式计算出的度数,在IOL植入术后普遍会出现不同程度的远视,据报道高远视度数可高达+10D.这是由于目前的角膜屈光度测量都是基于Gullstrand's模型眼计算的,在眼球角膜结构发生较大改变时,这些计算公式无法表达出来,从而导致错误.目前已有一些比较成功的校正方法用于克服此类计算误差,本文就这一些方法及进展并结合自己的临床经验围绕计算公式及计算公式中主要参数角膜屈光度重估等为重点进行介绍和讨论.
-
替代PRK和LASIK的激光角膜上皮磨削術(LASEK)
Objective To introduce and compare the one year' s result of LASEK (Laser Epithelial Keratomileusis) as an alternative to concurrent PRK and LASIK procedures for myopia. Methods This retrospective clinical study comprised operative and postoperative notes of consecutive 16 myopic patients (27 eyes, M:F=9:18) who had receied LASEK procedures with at least one year or more follow-up (12～18 months). And we comparved the LASEK with other surgeries such as PRK and LASEK in view-point of surgical advantages, visual improvement, and post-operative. complications such as corneal haziness, etc. Results We divided two groups of myopic patients according to the degrees of myopia (group 1 (N=14 eyes)-2.5D.～-6.00D.) and group 2 (N=13 eyes); -6.25D. ～-10.25D.). Through the LASEK procedure, surgical tension was surely less than that of LASIK which has always a possible complications concerned directly with a microkeratome. One week after LASEK, post-operative. Refractive powers and uncorrected visual improvement showed up to near normal ranges in all 27 eye cases. But In post-operative, corneal haziness, only trace-degree (0.5) was noted in one eye case of high myopic group. As other complications, we observed a failed case of epithelial flap making with a case of T-lens related central epithelial defect and a case of tight lens syndrome. Conclusion LASEK is to be the most safe and effective excimer laser refractive surgery as an alternative procedure of PRK and LASIK. LASEK has also an advantageous choice in high myopic cases having thin cornea, or narrow interpalpebral fissure or deep sunken eyeball etc.
