TOSCA治疗复杂屈光不正患者术中切削厚度的临床分析

目的:分析角膜地形图引导的准分子激光角膜切削术(TOSCA)治疗复杂屈光不正患者术中切削厚度。方法:选取在我院接受TOSCA治疗的复杂屈光不正患者23例42眼,等效球镜为-2.50～-13.50(平均-7.51±2.23)D。将其在实际工作中按TOSCA模式中计算出的切削厚度与按照其相同的切削直径的LASIK/LASEK模式计算的切削厚度进行对比。结果:术前平均裸眼视力0.11±0.19,最佳矫正视力0.98±0.16,术后6mo裸眼视力1.03±0.30,与术前裸眼视力比较差异有统计学意义(P<0.05),达到并保持在术前最佳矫正视力。术前平均等效球镜-7.51±2.23D,术后6mo的平均等效球镜-0.42±0.67D,控制在±0.50D以内,达到矫正近视的目的。按照TOSCA模式计算术中实际切削厚度为92.43±21.28μm,剩余厚度为409.17±25.47μm,而按照相同的切削直径和屈光度的传统的LASIK/LASEK模式中计算的切削厚度和剩余厚度分别为123.26±28.73,378.69±32.65μm,两种模式的切削厚度相差约30.83±21.86μm,差异有统计学意义(P<0.05)。结论:在治疗复杂屈光不正患者时,TOSCA手术模式的术中预测角膜切削厚度明显小于LASIK/LASEK手术模式,理论上提高了手术的安全性。     

近视眼二次LASIK手术临床疗效分析

目的:探讨近视眼二次LASIK手术病例临床特点、有效性和安全性。方法:回顾性系列病例研究。44例近视患者(72眼)接受二次LASIK,二次手术间隔时间为13.32±12.06(3～58)mo,二次LASIK术前平均残余屈光不正度为-2.56±1.56(-7.25～+1.13)D;分析年龄、屈光度、角膜中央厚度、角膜瓣厚度、残余角膜基质厚度的特点及其对残余屈光不正度的影响。结果:二次术后UCVA为0.89±0.19(0.5～1.2)μm,等效球镜度(SE)为0.05±0.57D。二次术前CCT为502.69±31.45μm,与理论残余的456.08±26.04μm差异有统计学显著性意义(t=-0.785,P=0.000);多元回归分析表明,在诸多因素中,术前预矫屈光度和切削深度对二次术前屈光度有显著性影响(F=73.442,P=0.000),回归方程:残余屈光不正度=-0.317+0.588×术前等效球镜+0.031×切削深度。结论:本组二次LASIK手术病例表明,预矫屈光度和切削深度是导致屈光回退的主要因素;术后角膜组织增生是LASIK远期屈光回退的机制之一;在严格控制角膜厚度和预矫屈光度的前提下,二次LASIK是安全、有效的。     

角膜瓣背面基质切削治疗LASIK术后屈光回退的安全性和有效性

目的：观察准分子激光角膜瓣背面基质切削（undersurface ablation of the flap, UAF）治疗LASIK术后屈光回退的安全性和有效性。方法：对12例22眼LASIK术后有屈光回退的患者进行角膜瓣背面基质切削,术前球镜度数平均为-2.27±0.88D,散光度数为-0.44±0.30D,中央角膜厚度平均为424.9±8.2μm,术后观察1a,随访检查包括术后视力、屈光不正度数、角膜后表面高度、波前像差仪等。采用t检验或χ2检验进行统计学处理。结果：术中测量角膜基质床厚度平均275.4±9.3μm; 角膜瓣厚度平均144.7±7.5μm,切削深度平均28.1±9.3μm。术后1a裸眼视力（uncorrected visual acuity, UCVA）4.99±0.04,最佳矫正视力（best corrected visual acuity, BCVA）5.03±0.04,BCVA相比术前无1例下降者。屈光不正球镜度数至术后1a时-0.22±0.19D,相比术前差异有统计学意义（t=10.232, P〈0.001）; 散光度数1a时-0.24±0.26D,与术前相比有统计学意义（t=2.365,P=0.028）。角膜后表面高度值术前1.95±1.68μm,术后1a 2.00±1.88μm,两者差异无统计学意义（t=0.090, P=0.929）。彗差由术前0.283±0.112μm变化到术后1a时0.331±0.149μm,两者差异无统计学意义（t=1.452, P=0.161）; 球差由术前0.320±0.119μm变化到术后1a时0.341±0.103μm,两者差异无统计学意义（t=0.390, P=0.674）。结论：以合理的手术设计为基础,UAF治疗LASIK术后屈光回退是安全和有效的,可以作为一种治疗屈光回退的选择之一。     

角膜屈光手术治疗成人弱视的疗效分析

目的:观察角膜屈光手术治疗成人屈光不正性弱视的疗效。方法:对53例76眼成人屈光不正性弱视患者行角膜屈光手术治疗,其中38眼行LASIK手术,32眼行薄瓣LASIK手术,6眼行LASEK手术。随访观察12mo,回顾性分析其疗效。结果:患者术前屈光度球镜-13.50～+3.00(平均-7.33±3.36)D,散光-4.25～+2.00(平均-1.40±0.92)D,最佳矫正视力平均0.57±0.06。术后1mo,裸眼视力平均0.64±0.16,与术前最佳矫正视力有显著性差异(P<0.05)。术后12mo,裸眼视力进一步提高,平均0.72±0.20,与术前最佳矫正视力有显著性差异(P<0.05),与术后1mo裸眼视力比较,有显著性差异。术后视力高于术前最佳矫正视力者43眼(57%)。术后视力与术前最佳矫正视力相同者33眼(43%)。结论:准分子激光角膜屈光手术治疗成人弱视,疗效可靠,可有效提高患者视力。     

PRK和LASIK治疗近视术后角膜地形图分析

目的分析准分子激光屈光性角膜切削术(photorefractive keratectomy,PRK)和准分子激光原位角膜磨镶术(laserin situ keratomileusis,LASIK)治疗近视术后角膜表面形态.方法对术前屈光度为(-3.00～-10.00)D,平均为(-608±1.21)D的患者76例(150眼)行PRK,75例(150眼)行LASIK,分为PRK和LASIK组.术后1、3、6、12个月行角膜地形图检查.结果角膜地形图形态分为平滑型、半圆型、钥匙孔型、肾型、中央岛型和不规则型.LASIK术后未见中央岛型.LASIK组平滑型明显多于PRK组(P≤0.01).两组各种类型角膜地形图所占比例的差异均有非常显著意义(P≤0 001).术后3个月,两组中各种类型所占比例基本稳定.两组角膜地形图均有逐渐变平滑的趋势.中央岛型和不规则型术后UCVA较术前BCVA下降≥2行的比例最高,平滑型最低.PRK组术后UCVA较术前BCVA下降≥2行的比例高于LASIK组(P≤0.05).结论LASIK术后角膜地形图形态较PRK规则.LASIK术后视力恢复较PRK好.     

伴眼球震颤的近视准分子激光屈光手术的观察

目的　探讨对伴有先天性眼球震颤的近视施行准分子激光角膜屈光手术的方法及疗效。方法　对16例(3 2眼)以水平震颤为主的先天性运动性眼球震颤的近视(矫正视力>0 .5 )施行准分子激光PRK13例(2 6眼) ,LASIK 3例(6眼) ,术中采用2 %利多卡因球周麻醉。术后随访时间6月。结果　视力:PRK 2 4眼、LASIK 5眼共2 9眼术后裸眼视力达到术前最佳矫正视力。屈光度:PRK 2 6眼术前平均为(-4 .86±0 .5 5 )D ,术后6月平均为( 0 . 5 2±0 . 46)D ;LASIK 6眼术前平均为(-6 . 72±0 . 76)D ,术后6月平均为(-0 .75±0 .87)D。结论　对矫正视力较好的伴有先天性眼球震颤的近视施行准分子角膜屈光手术和普通的近视一样可获得良好的临床效果。     

PRK和LASIK偏中心切削分析

目的　分析准分子激光屈光性角膜切削术 (photorefractivekeratectomy ,PRK)和准分子激光原位角膜磨镶术 (laserinsitukeratomileusis ,LASIK)治疗近视偏中心切削及其与临床效果的关系。方法　对术前屈光度为 -3 0 0D～ -10 0 0D ,平均 (-6 0 8± 1 2 1)D76例 (15 0眼 )行PRK ,75例 (15 0眼 )行LASIK ,分为PRK和LASIK组。术后 1、3、6、12月行角膜地形图检查。结果　两组偏中心距离大部分≤ 0 5 0mm ,偏中心方位大多位于鼻上象限 ,差异无显著意义 (P >0 0 5 )。偏中心距离 >0 5 0mm时 ,裸眼视力较术前最佳矫正视力下降≥ 2行所占比例明显高于偏中心距离≤ 0 5 0mm者 (P <0 0 0 1)。结论　偏中心切削与PRK和LASIK的手术方式无关。偏中心距离≤ 0 5 0mm ,对视力的影响不大 ,偏中心距离 >0 5 0mm时 ,术后裸眼视力较差。     

LASIK矫治PRK术后屈光度欠矫及回退

目的　探讨准分子激光原位角膜磨镶术(LASIK)用于矫治屈光性角膜切削术(PRK)后欠矫及屈光度回退的效果。方法　2 6例(4 9眼)因PRK术后屈光度欠矫及回退再行LASIK矫治。49眼PRK术前的屈光度为-5 . 5 0D～-10 . 0 0D ,平均(-6 2 5±1 .5 0 )D ,PRK术后欠矫及回退的度数为-2. 2 5D～-5 . 75D ,平均(-3 0±1. 12 )D。观察LASIK矫治术后裸眼视力、屈光度、最佳矫正视力及并发症。术后随访6月以上。结果　裸眼视力≥0 .5者42眼(85. 71% ) ,其中≥1 .0者2 3眼(4 6 .94% )。实际屈光矫正度在预测矫正度的±0. 75以内者为43眼(87 .76% ) ,1眼发生角膜瓣下上皮植入。结论　PRK术后屈光欠矫及回退而残留的近视度数可以用LASIK手术矫治,且疗效好、安全性高,但远期效果尚需进一步观察。     

PRK术中应用低浓度丝裂霉素治疗低中度近视

目的：评价PRK术中应用低浓度(0.02g/L)丝裂霉素(PRK+LMMC)30s治疗低、中度近视眼术后疗效。

方法：选取我院接受屈光性角膜切削术(PRK)治疗的30例57眼低、中度近视患者,术中应用0.02g/L的MMC 30s,将术后6mo的随访结果与同期接受准分子激光原位角膜磨镶术(LASIK)治疗的疗效进行比较。

结果：术后6mo,PRK+LMMC治疗组等值球镜屈光度0.210D、等值球镜屈光度在±0.50D范围内的发生率71.9%、裸眼视力≥1.0者77.2%,平均最佳矫正视力1.19±0.18; LASIK治疗组等值球镜屈光度-0.017D,等值球镜屈光度在±0.50D范围内的发生率70.1%,裸眼视力≥1.0者72.7%,平均最佳矫正视力1.16±0.19,两组比较差异均无统计学意义(P>0.05)。术后6mo,PRK+LMMC治疗组没有出现超过1级的haze,所有眼最佳矫正视力均好于术前。LASIK治疗组1眼因角膜上皮植入使最佳矫正视力较术前下降3行,其余眼最佳矫正视力均好于术前。

结论：PRK术中应用0.02g/L的MMC 30s治疗低、中度近视同LASIK具有同样的视力结果,避免了LASIK瓣的并发症,不失为一个可取的手术程序。     

激光去除角膜上皮的屈光性角膜切削术的临床观察

目的:探讨治疗性准分子激光角膜切削术去除角膜上皮进行准分子激光角膜切削进行屈光矫治随访1a的临床效果.方法:前瞻性分析2012-07/2014-07随访资料完整的16例30眼近视及近视散光的连续性病例,术中使用治疗性准分子激光角膜切削术去除角膜上皮,再进行屈光性准分子激光角膜切削完成屈光矫治.随访记录术后1、3、6、12mo的视裸眼视力(UCVA)、角膜haze及残余等效球镜度(MRSE).结果:术后各时期UCVA ≥0.5者与术前BCVA差异无统计学意义(P＞0.05).术后各时期UCVA≥1.0者较术前BCVA差异经卡方检验两两比较差异亦无统计学意义(P＞0.006).术后不同时期角膜haze值差异有统计学意义(F=16.751,P=0.000).术后1mo角膜haze值为0.71±0.25,随时间推移角膜haze逐渐减轻,无2级以上haze出现.术后lmo MRSE为0.9±0.87D,较术后3mo (0.5±0.65D)差异有统计学意义(t=2.017,P=0.048),而MRSE在术后3、6mo (0.5±0.65、0.5 ±0.45D)及12mo(0.25±0.4D)差异无统计学意义(F=2.389,P=0.098).结论:本组研究获得较好的临床视力结果,术后1 mo有轻度远视漂移及较明显的角膜haze,对于其远期屈光稳定性及视觉质量等仍需大样本及分组的临床研究.     

ORK-CAM角膜像差引导与传统切削模式近视LASIK手术比较研究

目的 探讨ORK-CAM角膜波阵面像差引导的近视LASIK手术的临床效果并与传统近视切削模式相比较.方法 回顾性分析接受近视LASIK手术的患者75例149只眼的临床资料.其中ORK-CAM角膜像差引导切削组4l例81只眼,常规切削组34例68只眼.统计患者术前和术后6个月的临床资料并进行手术前后以及两组间对比.主要观察指标包括裸眼视力、屈光度、角膜非球而系数、RMSh、RMS3-RMS7、球差、慧差以及三叶草像若值等.结果 两组术后角膜形态均由术前的长椭圆形变为扁椭圆形,ORK-CAM组角膜非球面系数改变较常规IASIK组小.两组术后角膜高阶像差均较术前显著增加.术后ORK-CAM组RMSh、RMS3、RMS4、球差以及三叶草像差值较常规IASIK组低,差异有统计学意义;术后ORK-CAM组6阶像差值较常规LASIK组高,二次球差是影响RMS6变化的主要因素.角膜Q值与球差值成正相关.结论 ORK-CAM角膜像差引导的个体化切削能够减小近视LASIK手术后角膜高阶像差的异常增加,术后角膜非球面性更接近于术前,有利于患者获得更好地术后视觉质量.     

Changes in central corneal thickness after laser in situ keratomileusis and photorefractive keratectomy

PURPOSE: To evaluate changes in corneal thickness after laser in situ keratomileusis (LASIK) and photorefractive keratectomy (PRK) in eyes with the same preoperative refraction, correlate these changes to postoperative refractive outcomes, and compare corneal healing process in a standardized subset of patients. METHODS: Central corneal thickness was measured by contact ultrasound pachymetry in 14 eyes of 8 patients with preoperative myopia of -6.00 D who had LASIK, and in 14 eyes of 8 patients with the same preoperative refractive error who had PRK. Measurements were taken preoperatively, and 1 week, 3, and 6 months after surgery. Data were evaluated and compared using the paired Student t-test and Pearson correlation coefficient. RESULTS: Mean preoperative central corneal thickness in the LASIK group was 549.14 +/- 37.4 microm, and in the PRK group, 552.64 +/- 34.9 microm. At 1-week postoperatively, mean central corneal thickness in the LASIK eyes was 467.28 +/- 29 microm and in the PRK eyes, 473.85 +/- 39.2 microm; at 6 months, central corneal thickness had increased in both groups compared to the 1-week values; LASIK eyes had a mean central corneal thickness of 481.42 +/- 23.0 microm and PRK, 481.50 +/- 35.3 microm. Mean postoperative refraction after 6 months was -0.48 +/- 0.30 D in the LASIK group and -0.67 +/- 0.35 D in the PRK group. CONCLUSION: Increase in central corneal thickness between 1 week and 6 months postoperatively occurred in both LASIK and PRK eyes, but differences were not statistically significant. No statistically significant differences were found in myopic regression between the two patient groups.     

飞秒激光制瓣LASIK及TransPRK手术治疗近视对角膜像差的影响

目的 观察飞秒激光制瓣LASIK手术及TransPRK手术治疗低中度近视患者对角膜像差的影响。设计 前瞻性病例对照研究。研究对象 等效球镜度-1.00 ~ -6.75 D的近视患者73例131眼。方法 37例68眼行飞秒激光制瓣LASIK手术,36例63眼行TransPRK手术。均使用阿玛仕准分子激光消像差切削模式。术前及术后1、3、6个月进行视力、屈光度、波前像差仪检查。主要指标 视力、残余屈光度、彗差、球差、总高阶像差。结果 术后1个月,飞秒激光制瓣LASIK组裸眼视力达到或超过术前最佳矫正视力者为75%,TransPRK组为47.62%（P=0.001）。术后3个月及6个月,飞秒激光制瓣LASIK组裸眼视力达到或超过术前最佳矫正视力者分别为86.76%、91.18%,TransPRK组分别为79.37%、90.48% （P=0.26,0.89）。术后残余屈光度,在术后3个月TransPRK组（0.13±0.35 D）较飞秒激光制瓣LASIK组（-0.02±0.41 D）略高,术后1个月及6个月均无显著差别。两组术后高阶像差均较术前提高（P<0.001）。术后1个月角膜彗差在TransPRK组为（0.25±0.10 μm）,较飞秒激光制瓣LASIK组（0.30±0.17 μm）小（P=0.04）;术后3、6个月角膜彗差在TransPRK组分别为（0.28±0.10 μm）、（0.30±0.12 μm）,与飞秒激光制瓣LASIK组（0.31±0.16 μm）、（0.35±0.11 μm）相似（P=0.12,0.13）。术后各时间点两组的球差、总高阶像差差异均无统计学意义。结论 飞秒激光制瓣LASIK手术及TransPRK手术治疗低中度近视患者术后角膜像差均有所提高,术后1个月TransPRK角膜彗差较飞秒激光制瓣LASIK小,术后3个月及6个月两种手术方式对角膜像差的影响相似。（眼科,2015,24：225-229）     

不同切削模式LASIK治疗中高度复性近视散光疗效

目的 评价不同切削模式LASIK治疗中高度复性近视散光的疗效.方法 应用美国雷赛LSX准分子激光机(5.3版)进行LASIK手术,常规球柱切削模式组(23只眼),术前平均裸眼视力(UCVA):0.15±0.09,球镜度数:(-4.40±2.07)D,柱镜度数(-2.42±0.47)D,随访时间(6.04±3.74)月;椭球切削模式组(33只眼),UCVA:0.13±0.05,球镜度数(-5.43±2.26)D,柱镜度数(-2.71±0.76)D,随访时间(6.91±5.10)月.结果 两组术后UCVA分别为1.11±0.17和1.05±0.10,球镜度数(-0.17±-0.77)D和(-0.18±0.89)D,柱镜度数(-0.62±0.39)D和(-0.64±0.68)D,两组间差异无统计学意义(P>0.05),术后Q值:0.60±0.35和0.29±0.59,两组间差异具有统计学意义(P<0.05).结论 LASIK 两种切削模式治疗中高度复性近视散光疗效确切、稳定,椭球型切削模式术后Q值更容易维持术前负性特征.     

Photorefractive keratectomy with mitomycin C versus LASIK in custom surgeries for myopia: a bilateral prospective randomized clinical trial

PURPOSE: To compare photorefractive keratectomy (PRK) with prophylactic use of mitomycin C (MMC) and LASIK in custom surgeries for myopic astigmatism. METHODS: Eighty-eight eyes of 44 patients with a minimum estimated ablation depth of 50 microm were randomized to receive PRK with MMC 0.002% for 1 minute in one eye and LASIK in the fellow eye. Uncorrected visual acuity (UCVA), best spectacle-corrected visual acuity (BSCVA), cycloplegic refraction, slit-lamp microscopy, contrast sensitivity, specular microscopy, aberrometry, and a subjective questionnaire were evaluated. Forty-two patients completed 6-month follow-up. RESULTS: Mean spherical equivalent refraction error before surgery and mean ablation depth were -3.99+/-1.20 diopters (D) and 73.09+/-14.55 microm in LASIK eyes, and -3.85+/-1.12 D and 70.7+/-14.07 microm in PRK with MMC eyes, respectively. Uncorrected visual acuity was significantly better in PRK with MMC eyes 3 months (P=.04) and 6 months (P=.01) after surgery. Best spectacle-corrected visual acuity and spherical equivalent refraction did not differ significantly in the groups during follow-up (P>.05). Significant haze was not observed in any PRK with MMC eye. Mean higher order aberration was lower in PRK with MMC eyes postoperatively compared with LASIK eyes (P=.01). Better contrast sensitivity was observed in PRK with MMC eyes than LASIK eyes (P<.05). The endothelial cell count did not differ significantly between groups (P=.65). In terms of visual satisfaction, PRK with MMC eyes were better rated. CONCLUSIONS: Photorefractive keratectomy with MMC appears to be more effective than LASIK in custom surgery for moderate myopia. During 6-month follow-up, no toxic effects of MMC were evident. Long-term follow-up is necessary to attest its safety.     

角膜地形图引导与波前像差优化的飞秒LASIK术后角膜地形图比较

目的 评估角膜地形图引导的飞秒激光制瓣的准分子激光原位角膜磨镶术（FS-LASIK）与波前像差优化的FS-LASIK治疗近视散光术后临床效果、角膜地形图的变化及角膜像差的差异。方法 前瞻性队列研究。将44例（87眼）近视散光患者根据接受的手术方式不同分成2组：Topography组（角膜地形图引导的个性化FS-LASIK,22例44眼）及Wavefront组（波前像差优化的FS-LASIK,22例43眼）。Topography组应用Wavelight Topolyzer角膜地形图仪采集角膜地形图数据。术后6个月,对2组视力、屈光度、角膜不规则指数、激光切削的居中性及角膜波前像差采用独立样本t检验进行比较。结果 术后6个月,2组间裸眼视力（UCVA）及最佳矫正视力（BCVA）的差异均无统计学意义,无一例出现术后BCVA低于术前。术后2组间球镜度、柱镜度及等效球镜度差异亦无统计学意义。Topography组患者术后角膜表面变异指数（ISV）（39.9±13.0）低于Wavefront组（44.9±12.2）,差异有统计学意义（t=-2.296,P<0.05）,2组术后ISV均较术前增加（t=5.216、7.870,P<0.05）。Topography组患者术后平均切削偏心量[（0.24±0.29）mm]低于Wavefront组[（0.29±0.31）mm],但2组间差异无统计学意义（t=-1.005,P>0.05）。术后6个月,Topography组角膜水平彗差（Z31）及球差（Z40）[（-0.166±0.357）μm和（0.390±0.263）μm]均低于Wavefront组[（-0.362±0.353）μm和（0.486±0.164）μm],差异有统计学意义（t=2.325、-2.096,P<0.05）。结论 角膜地形图引导的FS-LASIK与波前像差优化的FS-LASIK相比较同样安全有效,但前者术后角膜表面规则性更好,引入的角膜高阶像差更低。     

FS-LASIK联合Triple-A切削模式矫正超高度近视

观察飞秒激光辅助制瓣准分子激光原位角膜磨镶术（FS-LASIK）联合节约角膜切削厚度的 Triple-A切削模式矫正超高度近视的临床疗效。方法：前瞻性临床研究。选取2016年1-7月于南京中医药大学附属医院接受角膜屈光手术的高度近视患者92例（184眼），根据等效球镜度（SE）分为高度近视组（-9.0 D0.05）。术后6个月，2组有效性指数和安全性指数差异无统计学意义（均P>0.05）。2组术后均有远视漂移，超高度近视组早期更为显著，2组在术后3个月屈光度趋于稳定。高度近视组和超高度近视组术后角膜总高阶像差、球差和水平彗差引入量在时间上和组别间差异有统计学意义（P<0.05），角膜垂直彗差引入量在时间上和组别间差异无统计学意义。结论：FS-LASIK联合Triple-A切削模式矫正高度近视和超高度近视都能够有效地改善患者的视力，有较好的安全性、有效性和稳定性。     

Comparison of laser in situ keratomileusis and photorefractive keratectomy results: long-term follow-up

PURPOSE: To compare the results of photorefractive keratectomy (PRK) and laser in situ keratomileusis (LASIK) over a 4-year follow-up. SETTING: Miyata Eye Hospital, Miyazaki, Japan. METHODS: This comparative retrospective study comprised 22 eyes (22 patients) that had PRK and 18 eyes (18 patients) that had LASIK. To be included, the patient had to have completed a 4-year follow-up. Uncorrected visual acuity (UCVA), best spectacle-corrected visual acuity (BSCVA), percentage of eyes within +/-0.5 diopter (D) of the targeted refraction, central corneal thickness, and the anterior and posterior corneal elevations were compared between the PRK and LASIK groups. RESULTS: The mean UCVA was significantly better in the LASIK group than in the PRK group at 6 months (P = .0043) and 1 year (P = .0044). At 2 years, there was no significant difference in the mean UCVA between the 2 groups. The mean BSCVA was significantly better in the LASIK group than in the PRK group at 6 months (P<.0001), 1 year (P<.0001), and 2 years (P = .0083). At 3 and 4 years, there was no significant difference in the mean BSCVA between the 2 groups. The percentage of eyes within +/-0.5 D of the targeted refraction was not significantly different between groups at any time. CONCLUSIONS: The superiority of LASIK over PRK in short-term efficacy was not retained 4 years after surgery. The main reasons were a myopic shift and a decline in UCVA at the last follow-up in the LASIK group.