Comparison of visual results between laser-assisted subepithelial keratectomy and epipolis laser in situ keratomileusis to correct myopia and myopic astigmatism

PURPOSE: To compare the visual results after laser-assisted subepithelial keratectomy (LASEK) and epipolis laser in situ keratomileusis (epi-LASIK) to correct myopia. DESIGN: Retrospective, interventional, nonrandomized comparative study. METHODS: Patients treated with LASEK to correct myopia < or = -9.00 diopters (D) were compared to age- and refraction-matched patients treated with epi-LASIK using the same excimer laser (Esiris; Schwind Eye Tech Solutions, Kleinostheim, Germany). The epithelial flap was replaced after the ablation in every case. The visual results after both procedures were compared at each postoperative visit (one day, one week, one and three months). RESULTS: Ninety-four consecutive eyes were included in the study (47 in each group), matched for age and refraction. The preoperative spherical manifest refraction was -3.98 +/- 2.40 D in the LASEK group and -3.95 +/- 2.40 D in the epi-LASIK group (P = .9) (range -0.50 to -9.00 D). The uncorrected visual acuity (UCVA) one day postoperatively was 0.7 +/- 0.2 and 0.5 +/- 0.2 (P < .001), and one week after surgery it was 0.8 +/- 0.2 and 0.7 +/- 0.2, respectively (P = .1). The difference was again statistically significant one month after surgery (0.94 +/- 0.1 after LASEK, 0.82 +/- 0.1 after epi-LASIK, P < .001), but not three months postoperatively (1.06 +/- 0.21 and 1.03 +/- 0.18, respectively, P = .1). UCVA was > or =1.0 in 78.7% of LASEK eyes and 65.9% of epi-LASIK eyes three months after surgery. At that moment, the safety indices were 0.99 +/- 0.1 after LASEK and 0.93 +/- 0.1 after epi-LASIK (P = .04). The efficacy indices were 0.97 +/- 0.1 and 0.89 +/- 0.1, respectively (P = .01). CONCLUSIONS: Our results suggest a faster visual rehabilitation and better safety and efficacy outcomes after LASEK compared to epi-LASIK with repositioning of the epithelial flap when correcting low to moderate myopia.     

Surgically-induced astigmatism after laser in situ keratomileusis for spherical myopia

PURPOSE: To characterize the surgically-induced-astigmatism (SIA) associated with spherical LASIK. METHODS: Refractive outcomes in 70 eyes that underwent primary myopic LASIK with purely spherical ablation were analyzed. The Summit Apex Plus excimer laser was used. The Bausch & Lomb Hansatome with the 180-microm plate was used to produce superiorly hinged flaps. The relationship between refractive astigmatism and corneal topographic astigmatism was analyzed using linear regression and vector analysis. RESULTS: There was a statistically significant negative correlation (slope = -0.21) between refractive surgically-induced astigmatism and preoperative topographic cylinder. A 0.24-D with-the-rule shift was also found. Surgically-induced astigmatism was not correlated with the magnitude of laser ablation. CONCLUSION: The lamellar keratotomy portion of LASIK reduces pre-existing corneal astigmatism and produces a relative steepening of the hinge meridian.     

Corneal irregular astigmatism after laser in situ keratomileusis for myopia

AIMS: To quantitatively evaluate the changes in corneal irregular astigmatism after laser in situ keratomileusis (LASIK) in relation to the amount of laser ablation. METHODS: In 189 eyes of 116 patients undergoing LASIK for myopia, corneal topography was obtained before and 1 month after surgery. Using Fourier harmonic analysis of the topography data, corneal irregular astigmatism (asymmetry and higher order irregularity) was calculated. RESULTS: By surgery, asymmetry component significantly increased (p < 0.0001, Wilcoxon signed rank test), while higher order irregularity did not (p = 0.767). The increases in the asymmetry component significantly correlated with ablation depth (Spearman rank correlation coefficient r(s) = 0.440, p < 0.0001). No significant correlation was found between changes in higher order irregularity and ablation depth (r(s) = 0.137, p = 0.074). CONCLUSION: LASIK significantly increases the asymmetry component of the cornea which is dependent on the amount of laser ablation.     

Correction of myopia and astigmatism using laser in situ keratomileusis

Patients and methods: In order to better define the potential advantages and risks of laser in situ keratomileusis (LASIK), we designed a prospective study including 73 eyes. Results: After 6 months, 62 eyes were examined. Myopia was corrected from –6.10 ± 3.12 (mean ± standard deviation) to + 0.04 ± 0.66 D, with 54 eyes (87.1 %) being within ± 1.00 D of emmetropia. Astigmatism was corrected from –1.07 ± 1.02 to –0.32 ± 0.89 D. Uncorrected visual acuity was 0.5 or better in 59 eyes (95.2 %) and 1.0 or better in 27 eyes (43.5 %) 6 months postoperatively. More than one line in best-corrected visual acuity was lost by 6 eyes (9.7 %), with most of these eyes being highly myopic. There was no change or a gain in lines in best corrected visual acuity in 42 eyes (66.1 %). Intraoperative complications arose in two eyes (2.7 %); in one eye, visual acuity was temporarily decreased. More treatments were performed in 7 eyes (9.6 %). Postoperatively, no haze, scars or central islands were detected. Patient satisfaction after LASIK was high: 97.3 % were pleased or very pleased with the result. Conclusions: In conclusion, LASIK is effective in the correction of myopia and myopic astigmatism. Although complications more frequently occurred in the correction of higher refractive errors, LASIK seems to be relatively safe compared with other refractive methods.      

单纯近视准分子激光原位角膜磨镶术后散光分析

目的 :探讨准分子激光原位角膜磨镶术 (LASIK)治疗单纯近视所产生的散光的变化规律及其原因和预防措施。方法 :137例 (188眼 )单纯近视行LASIK手术 ,分别于术后第 1天、第 1周、第 1、第 3、第 6个月复查视力、屈光度等。结果 :LASIK术后散光度明显高于术前 ,虽有逐渐减少的趋势 ,但至术后第 3～ 6个月仍有 5 2眼 (占 2 7.6 6 % )具有 0 .5D以上的散光 ,而且裸眼视力低于术前最佳矫正视力。角膜切削深度、患者年龄与散光大小成正相关 (r =0 .372 ,P <0 .0 0 1;r=0 .2 4 5 ,P <0 .0 5 )。鼻侧蒂角膜瓣散光的发生率高于上方蒂角膜瓣 (P <0 .0 0 1) ;散光的发生与性别无关。结论 :LASIK术后散光影响术后视力恢复 ,散光的发生与角膜损伤修复、切削偏中心、角膜瓣移位等因素有关     

Surgically induced astigmatism after laser in situ keratomileusis for spherical myopia

PURPOSE: To study risk factors for surgically induced astigmatism (SIA) after laser in situ keratomileusis (LASIK). METHODS: In a retrospective case control study of 104 eyes (52 patients) that underwent LASIK for myopia (spherical ablation alone), two groups were studied: 42/104 eyes with SIA, and controls (62/104 eyes). The main variables studied were preoperative refraction, corneal thickness, preoperative keratometric power, amount of ablation, ablation zone diameter, flap thickness, flap size, and the presence of complications. The effect of SIA on visual performance was also evaluated. RESULTS: The mean myopia for which LASIK was undertaken was -4.50 +/- 2.04 D. Mean scalar astigmatism induced was 0.35 +/- 0.50 D at 1 month, 0.33 +/- 0.40 D at 3 months, and 0.16 +/- 0.60 D at 6 months. SIA based on refractive cylinder was 0.66 +/- 0.29 D at 1 month, 0.54 +/- 0.32 D at 3 months, and 0.49 +/- 0.34 D at 6 months. Mean axis of vector induced astigmatism was 82.5 degrees +/- 57 degrees at 1 month, 98.86 degrees +/- 52.4 degrees at 3 months, and 113.9 degrees +/- 62.6 degrees at 6 months. Risk factors associated with the occurrence of SIA were preoperative keratometric power of >44 D [OR (95% CI); 1.97 (0.62 to 6.26)], ablation zone diameter of <6 mm [OR (95 % CI) 2.76; (0.6 to 12.6)], and suction ring diameter of 8.5 mm [OR (95% CI) 12.46; (2.0 to 77.38)]. The occurrence of SIA had no significant effect on uncorrected Snellen high contrast visual acuity, contrast sensitivity, and glare in comparison with controls. CONCLUSION: Surgically induced astigmatism was more likely to occur with the use of smaller suction rings of 8.5 mm and in ablation zones less than 6 mm. Parameters for visual performance were not affected by the presence of surgically induced astigmatism.     

Epi-LASIK和LASIK矫治高度近视的疗效比较

目的探讨微型角膜刀准分子激光角膜上皮瓣下磨镶术(Epi-LASIK)和准分子激光原位角膜磨镶术(LASIK)矫治高度近视的疗效。设计前瞻性、病例对照研究。研究对象62例(123眼)高度近视患者。方法对62例(123眼)高度近视患者进行Epi-LASIK(28例56眼)或LASIK(34例67眼)手术。由患者自行决定采用何种术式,对于角膜相对较薄者和从事职业存在角膜瓣风险者,医生推荐Epi-LASIK手术。观察术中术后并发症。记录两组患者术后1周、1、3、6个月裸眼视力(UCVA)、最佳矫正视力(BCVA)、屈光状态及总的高阶波前像差均方根(RMS)。主要指标UCVA、BCVA、屈光状态及总的高阶波前像差RMS值。结果术中、术后无严重并发症。术后1周Epi-LASIK组UCVA≥0.8眼数比例(46.4%)明显少于LASIK组(77.6%),差异有统计学意义(P=0.0003);术后1、3、6个月Epi-LASIK组UCVA≥0.8眼数比例(85.7%、94.6%、91.1%)与LASIK组(92.5%、95.5%、94.0%)差异无统计学意义(P=0.590、0.822、0.530)。两组术后的BCVA无一例下降。Epi-LASIK组术后1周、1、3、6个月等效球镜值在±0.50D以内的比例(42.9%、51.8%、60.7%、64.3%)与LASIK组(53.7%、59.7%、71.6%、73.1%)比较差异无统计学意义(P= 0.230、0.378、0.200、0.290)。两组术后的高阶像差RMS均较术前增大:Epi-LASIK组术后l、3、6个月的高阶像差RMS值(1.51±0.77)μm、(1.32±0.76)μm、(1.18±0.71)μm与术前(0.87±0.27)μm相比,差异均有统计学意义(P=0.016、0.019、0.026);LASIK组术后1、3、6个月的高阶像差RMS值(2.41±0.81)μm、(2.17±0.63)μm、(1.89±0.87)μm与术前(0.91±0.22)μm相比,差异亦均有统计学意义(P=0.011、0.008、0.006)。Epi-LASIK组对高阶像差的影响小于LASIK组:两组之间术后1、3、6个月高阶像差RMS比较差异均有统计学意义(P=0.039、0.035、0.033)。Epi-LASIK组Ⅰ级角膜上皮下雾状混浊(haze)2眼。结论Epi-LASIK矫正高度近视虽然视力恢复较LASIK慢,但能获得更好的视觉质量。(眼科,2007,16:336-339)     

Long-term results of laser in situ keratomileusis for high myopia

The objective of this study was to evaluate the results of laser in situ keratomileusis (LASIK) for high myopia after a follow-up of two years. A total of 42 eyes from 33 patients with high myopia (range: -9.00 D to -25.50 D) were studied. LASIK was performed using an automated microkeratome (Steinway, USA) and OmniMed II excimer laser with the standard MKM program (Summit Technology, Inc., Waltham, MA) in all patients. The patients were followed up at one, three, six, 12 and 24 months. During follow-up manifest refraction and best corrected and uncorrected visual acuity were measured. Any complications were also analyzed. The two-year follow-up results were as follows. The mean postoperative manifest spherical equivalents (MSE) were -0.51 D at one month, -1.09 D at three months, -1.78 D at six months, -2.17 D at 12 months and -2.61 D at 24 months. Myopic regression continued during the two-year follow-up (p < 0.05). The accuracy of the intended postoperative correction within +/- 2.00 D was 73.8% at one month, 69.1% at three months, 52.4% at six months, 52.4% at 12 months, and 45.2% at 24 months. The best corrected visual acuity (BCVA) was unchanged or increased in 35 eyes (83.3%). Only three eyes (7.2%) lost two or more lines of BCVA. This was due to irregular astigmatism in one eye, macular degeneration in one eye, and rhegmatogenous retinal detachment in one eye. In this study, LASIK was effective and safe in the correction of high myopia, however continuous myopic regression was seen over the two-year follow-up. Refining the nomogram to adjust for progressive myopic regression will be necessary in order to obtain better results.     

准分子激光原位角膜磨镶术矫正近视散光的临床探讨

目的 探讨准分子激光原位角膜磨镶术(LASIK)矫正近视散光的临床疗效.方法 对散光等于和高于-1.50D的复性近视散光和单纯近视散光69例(115眼)施行LASIK矫正,其中循规性散光76眼,逆规性散光24眼,斜轴散光15眼.散光度-1.50D～-4.00D的106眼,-4.00D以上的9眼.结果 术后6个月达预期矫正视力者105眼(91.30%),实际矫正散光度接近术前预期矫正散光度,柱镜差值(-0.75±0.50)D者101眼.角膜地形图由术前96眼(83.48%)领结形到术后90眼(78.26%)为平滑的圆形或椭圆形.术前散光高于-4.00D的9眼中3眼未达到术前最佳矫正视力,4眼眩光、虚影不适症状持续存在.结论 LASIK矫正近视散光同治疗单纯近视一样安全有效,预测性好,但-4.00D以上的高度散光疗效欠佳.视觉质量下降.     

LASEK与PRK矫正近视及近视散光的疗效比较

目的 比较LASEK与PRK手术矫正不同程度近视及近视散光的有效性、安全性及稳定性。方法 70名患者(140眼)，分为中低度近视组39人(78眼)、高度近视组31人(62眼)。患者一眼行LASEK手术，对侧眼行PRK手术，术后观察术眼疼痛情况、上皮愈合时问、角膜上皮下雾状混浊(haze)、术后裸眼视力6个月。结果LASEK与PRK术后上皮愈合时间及术眼疼痛指数无明显差异；中低度近视组两种手术后裸眼视力无显著差异；高度近视组裸眼视力及角膜haze程度差异显著。结论 LASEK矫正不同程度近视均能取得较好的临床效果，术后裸眼视力及视力稳定程度优于PRK，特别表现在高度近视组。     

In situ laser keratomileusis for correcting myopia and astigmatism of different severity]

Myopia and astigmatism were corrected by laser specialized keratomylesis in 1357 eyes with myopia of 1-18.0 diopters and astigmatism up to -5.5 diopters. The proposed method is highly effective in myopia of different severity and astigmatism and is preferable to photorefraction keratectomy.     

矢量法分析LASEK和LASIK矫正高度散光的疗效

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 keratomileusis,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 visual acuity,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。     

激光角膜上皮瓣下磨镶术和激光原位角膜磨镶术治疗中高度近视的对比研究

目的比较激光角膜瓣下磨镶术(LASEK)和激光原位角膜磨镶术(LASIK)治疗中高度近视的临床效果. 方法中高度近视患者198例(394只眼).其中LASEK手术治疗93例(184只眼), LASIK手术治疗105例(210只眼). 结果术后1天,LASIK 组28 %裸眼视力达到1.0,LASEK组无1例裸眼视力达到1.0.术后1周、1、3、6月裸眼视力大于或等于1.0者,两组比较差异无显著性 (P=0.36,P=0.58,P=0.44,P=0.64).角膜地形图分析平均角膜中央屈光力与周边屈光力的差异,LASEK组(0.69)明显小于LASIK组(2.62).结论 LASEK手术矫正中高度近视均有良好的治疗效果,是一种安全、有效、预测性好的屈光手术.     

Bitoric laser in situ keratomileusis for astigmatism

PURPOSE: To evaluate the efficacy, predictability, and safety of bitoric laser in situ keratomileusis (LASIK) for the correction of mixed astigmatism. SETTING: Instituto Oftalmológico de Alicante, Alicante, Spain. METHODS: This prospective study included 28 eyes of 21 patients with mixed astigmatism who had bitoric LASIK using the Hansatome microkeratome (Bausch & Lomb Surgical) and the Chiron Technolas 217 excimer laser (Bausch & Lomb Surgical). The main outcome measures were uncorrected visual acuity (UCVA), best corrected visual acuity (BCVA), defocus equivalent, blur strength, and refraction. RESULTS: Six months after bitoric LASIK, the mean UCVA was 0.70 +/- 0.23 (SD). The percentage of eyes with a UCVA of 20/40 or better was 78.6% and of 20/20, 21.4%. There was a statistically significant increase in the mean BCVA from 0.71 +/- 0.19 before surgery to 0.83 +/- 0.15 at 6 months (P =.0004). Three eyes (10.7%) lost 1 line of BCVA; 19 eyes (67.9%) gained 1 or more lines. The mean preoperative astigmatism of -4.04 +/- 1.13 diopters (D) was reduced to -0.67 +/- 0.79 D after surgery. The defocus equivalent was less than 1.00 D in 75.0% of eyes and less than 0.50 D in 64.3%. Vector analysis showed that the mean achieved correction was 97.4% of the intended correction. CONCLUSIONS: Bitoric LASIK was a safe, effective, and predictable procedure in the treatment of mixed astigmatism. It is a means to improving BCVA in a significant percentage of patients.     

小光斑飞点扫描准分子激光角膜原位磨镶术治疗近视疗效观察

目的评价小光斑飞点扫描准分子激光系统应用于准分子激光角膜原位磨镶术(LASIK)治疗近视的疗效.方法将79例150只眼按术前屈光度分三组,Ⅰ组-0.50～-6.00D,Ⅱ组-6.25～-10.00D,Ⅲ组-10.25～-14.00D,对LASIK术后超过3个月的患者的视力、屈光度、切削区大小、偏中心情况进行随访分析.结果术后3个月时,三组的裸眼视力均达0.5以上,达1.0或以上者分别为83.1%、79.6%、50.0%,1.2或以上者分别为48.3%、38.8%、8.3%,有27眼(18%)的术后裸视和40眼(26.7%)的术后最好矫正视力分别大于术前最好矫正视力.三组术后屈光度在预期矫正度±1.0D以内者分别为100%、95.9%、91.7%,±0.5D以内者分别为88.8%、86.5%、83.3%,平均实际切削区直径为(7.35±0.33)mm,平均偏中心(0.22±0.21)mm.结论使用小光斑高速飞点扫描准分子激光系统的LASIK治疗近视的初期临床结果较好,较大的切削光区和良好的中心定位可有效减少手术并发症和提高术后的预测性.     

Correction of myopia and astigmatism after penetrating keratoplasty with laser in situ keratomileusis

PURPOSE: We evaluated whether laser in situ keratomileusis (LASIK) was a safe and effective treatment for myopia and astigmatism after penetrating keratoplasty (PK). METHODS: We performed a retrospective review of medical records of all the patients who underwent LASIK following PK at the University of Minnesota between January 1999 and March 2000. RESULTS: Seventeen patients (20 eyes) underwent LASIK following PK between January 1999 and March 2000. Mean age of the patients at the time of LASIK was 37 years (range, 20-62). Keratoconus was the indication for PK in the majority of the eyes (73.7%). Anisometropia and/or contact lens intolerance was the indication for LASIK following PK. No intraoperative complications occurred. Following LASIK, the best spectacle-corrected visual acuity remained within 1 line of preoperative visual acuity in 94.7% of the eyes. The mean sphere was reduced by 3.93 diopters (80.0%) and the mean cylinder was reduced by 2.83 diopters (69.9%) from the preoperative values at the last follow-up visit. Uncorrected visual acuity became 20/40 or better in 73.7% of the eyes after LASIK. CONCLUSIONS: LASIK is a safe procedure in eyes in which PK has previously been performed. LASIK is effective in the treatment of myopia and astigmatism following PK.     

Laser in situ keratomileusis retreatment for residual myopia and astigmatism

PURPOSE: To evaluate the visual and refractive results of laser in situ keratomileusis (LASIK) retreatment on eyes with residual myopia with or without astigmatism. METHODS: LASIK retreatment was performed on 35 eyes of 23 patients for correction of residual myopia, with or without astigmatism, with a mean manifest spherical equivalent refraction of -2.17+/-0.82 D (range, -1.00 to -3.87 D) and mean refractive astigmatism of -0.55+/-0.61 D (range, 0 to -1.75 D). Retreatment was performed 3 to 18 months after primary LASIK (mean, 5.1+/-2.6 mo). The corneal flap of the previous LASIK was lifted and laser ablation was performed using the Chiron-Technolas Keracor 116 excimer laser. Follow-up was 12 months for all eyes. RESULTS: At 1 year after retreatment, manifest spherical equivalent refraction was reduced to a mean -0.23+/-0.28 D (range, 0 to -0.87 D), and refractive astigmatism was reduced to a mean -0.16+/-0.25 D (range, 0 to -0.75 D). Thirty-two eyes (91.5%) had a manifest spherical equivalent refraction within +/-0.50 D of emmetropia, and 33 eyes (94.3%) had 0 to 0.50 D of refractive astigmatism. Uncorrected visual acuity was 20/20 or better in 11 eyes (31.4%). Spectacle-corrected visual acuity was not reduced in any eye after retreatment. There were no significant complications. CONCLUSION: LASIK retreatment was effective for correction of residual myopia or astigmatism after primary LASIK. Refractive results were predictable with good stability after 3 months. Lifting the flap during LASIK retreatment was relatively easy to perform and did not result in visual morbidity in eyes treated from 3 up to 18 months after primary LASIK.     

Multiple regression and vector analyses of laser in situ keratomileusis for myopia and astigmatism.

PURPOSE: To construct a quantitative model relating refractive results to laser settings and other factors. METHODS: A prospective clinical trial was performed, including 14 surgeons and 523 eyes of 278 patients who desired correction of myopia from -1.00 to -16.00 D (mean, -6.20 D) and astigmatism up to 6.00 D (mean, 1.10 D). Myopia and astigmatism were corrected by laser in situ keratomileusis (LASIK) with sequential spherical and cylindrical ablations using a 5.5-mm ablation zone and a transition zone to 7.0 mm. The Nidek EC-5000 excimer laser and the Chiron Automated Corneal Shaper were used. RESULTS: Surgically induced refractive changes 3 months after surgery were measured. Spherical ablation by LASIK produced a 19% greater refractive change than that predicted by the Nidek PRK algorithm. The laser setting needed to achieve each 1.00 D of cylinder correction induced 1.30 D change in spherical equivalent refraction (0.80 D more than expected). Patient age and nonlinear effects had small but statistically significant influences on refractive outcome. Sex, left/right eye, and surgeon were not significant factors. Residual variations in spherical equivalent refraction included a 0.50-D constant plus 9% of the predicted spherical equivlanet change. Residual variations in the parallel and orthogonal components of cylinder correction were, respectively, 28% and 13% of the predicted cylinder change plus a 0.30-D constant component. The standard deviation of axis alignment error for cylinder ablation was 3.7 degrees. CONCLUSIONS: Cylindrical ablation produced a spherical change that was larger than expected. To compensate for this, spherical ablation should be reduced in eyes with astigmatism. Variability in the correction of astigmatism was proportionally larger than that for spherical correction and was primarily due to magnitude rather than axis error.