实时虹膜识别引导LASIK与常规LASIK治疗近视性散光疗效对比研究

目的 对比观察实时虹膜识别引导的LASIK与常规LASIK治疗近视性散光的临床疗效.方法 采用随机对照研究.接受实时虹膜识别引导LASIK手术的近视性散光患者105例(196只眼)作为试验组,接受常规LASIK手术的近视性散光患者104例(195只眼)作为对照组,对两组患者术后1个月、3个月、6个月的裸眼视力、最佳矫正视力、散光度、散光轴向等进行比较.结果 静态虹膜识别检测出眼球旋转偏移角度为(2.74±2.05)°,动态虹膜识别检测眼球旋转变化范围为0～6.5°.术后6个月两组裸眼视力均≥0.5,术后最佳矫正视力均未丢失;术后6个月时,试验组裸眼视力≥术前最佳矫正视力的患者(181只眼,92.3％)多于对照组(167只眼,85.6％);试验组的平均散光(-0.22±0.20)D低于对照组(-0.34±0.35)D,差异均有统计学意义(P＜0.01).术后6个月,试验组无散光眼(79只眼,40.3％)多于对照组(55只眼,28.2％),差异有统计学意义(P＜0.05);对照组斜轴散光明显增加.结论 实时虹膜识别引导的LASIK能够有效校正LASIK术前和术中的眼球旋转偏差,使散光度数和轴向的治疗更加精确.     

实时虹膜识别技术在准分子激光原位角膜磨镶术矫正中高度近视性散光中的应用

目的 评价实时虹膜识别技术在准分子激光原位角膜磨镶术(LASIK)矫正中高度近视性散光中的价值.方法 采用随机对照研究,接受实时虹膜识别引导LASIK手术的近视性散光49例(90眼)作为试验组,接受常规LASIK手术的近视性散光49例(91眼)作为对照组.对两组术后1个月、3个月、6个月的裸眼视力、最佳矫正视力、散光度、散光轴向等进行比较.结果 静态虹膜识别检测出眼球旋转偏移角度为2.83°±2.65°,动态虹膜识别检测眼球旋转变化范围为0°～6°.术后6个月时,试验组裸眼视力≥术前最佳矫正视力86眼(95.6％)多于对照组75眼(82.4％)(P＜0.01);试验组的平均散光(-0.29 ±0.23)D低于对照组(-0.45 ±0.31)D(P ＜0.05).术后6个月,试验组无散光眼40眼(44.4％)多于对照组26眼(28.6％)(P＜0.05);对照组斜轴散光明显增加.结论 实时虹膜识别技术能够有效校正LASIK术前和术中的眼球旋转偏差,使散光度数和轴向的治疗更加精确.     

实时虹膜识别联合波前引导LASIK治疗中高度近视性散光

目的:评价实时虹膜识别技术应用在波前引导准分子激光原位角膜磨镶术（laser in situkeratomileusis, LASIK）治疗中高度近视性散光中的准确性、稳定性。方法:采用随机对照研究,接受实时虹膜识别联合波前引导LASIK手术的近视性散光患者57例104眼作为试验组,接受常规波前引导LASIK手术的近视性散光患者58例107眼作为对照组,对两组患者术后1,3,6mo的裸眼视力、最佳矫正视力、散光度、散光轴向、波前像差等进行比较。结果:静态虹膜识别检测出眼球旋转偏移角度为2.61°±2.08°,动态虹膜识别检测眼球旋转变化范围为0°～5°。术后6mo时,试验组裸眼视力≥术前最佳矫正视力的患者（96眼,92.3%）多于对照组（78眼,72.9%）,差异有统计学意义(P＜0.01);试验组的平均散光（-0.28±0.26D）低于对照组(-0.44±0.35D),差异有统计学意义(P＜0.05)。术后6mo,试验组无散光眼（49眼,47.1%）多于对照组（31眼,29.0%）, 差异有统计学意义(P＜0.01)。当瞳孔直径为6mm时,试验组彗差的增加少于对照组,差异有统计学意义(P＜0.01)。结论:实时虹膜识别技术能够有效校正LASIK术前和术中的眼球旋转偏差及瞳孔中心移位,使散光度数和轴向的治疗更加精确,同时提高视觉质量。     

Zyoptix虹膜识别技术引导的LASIK治疗近视散光的临床疗效分析

目的 评价Zyoptix系统虹膜识别技术应用在LASIK治疗近视散光眼的准确性、稳定性及可预测性。方法 对接受LASIK治疗近视散光患者193人（363眼）,采用随机表分为Zyoptix、Planoscan两组,Zyoptix组97人（181眼）为试验组采用虹膜识别引导的LASIK治疗,Planoscan组96人（180眼）为对照组采用传统LASIK模式进行治疗。两组术前均用Zywave像差仪检测散瞳前后瞳孔偏移数据,Zyoptix组治疗前进行虹膜识别,确定患者个人信息、瞳孔中心总体偏移量和眼球旋转角度并在治疗时加以补偿、术后随访6个月对手术前后视力、散光度及轴向变化进行观察。结果 术后6个月两组裸眼视力均≥0.5,术后最佳矫正视力（BCVA）均未丢失,Zyoptix组比术前BCVA≥1行的有62眼（34.3%）,≥2行的有24眼（13.3%）,Planoscan组比术前BCVA≥1行的有51眼（28.3%）,≥2行的有16眼（8.9%）。术后6个月Zyoptix组散光度为（-0.26±0.25）D,Planoscan组（-0.37±0.36）D,两者比较差异显著有统计学意义（t=3.37,P〈0.01）,两组SimK’sAsting分别为（-0.72±0.82）D、（-0.94±0.86）D两者比较差异有统计学意义（t=2.49,P〈0.05）。术后6个月无散光例数Zyoptix组为67眼（37.0%）,Planoscan组为47眼（26.1%）,两者比较差异有统计学意义（X2=4.97,P〈0.05）。结论 虹膜识别引导下LASIK对于散光矫正的准确性、可预测性优于传统LASIK。     

个性化波前引导的LASIK矫正中度以上近视散光的初步观察

目的探讨个性化波前引导的LASIK矫正中、高度散光的效果和安全性。方法接受LASIK治疗的近视散光患者76例（145只眼）,随机分为波前组和对照组：波前组39例（73只眼）,对照组37例（72只眼）;两组性别,散光度数大致相同。波前组行波前和虹膜识别引导的LASIK,对照组行普通LASIK,对比观察两者的治疗效果。结果术后3个月时,波前组裸眼视力1．0以上者为69只眼（94．5％）;对照组为63只眼（87．5％）。波前组最佳矫正视力提高1行以上的患者比例为36只眼（49．3％）,对照组为19只眼（26．4％）,两者比较有显著性差异（P〈0．01）。当瞳孔直径为6mm时,对照组术后高阶像差RMS平均增幅为107％,波前组平均增幅明显小于对照组,为41％,两组间比较有显著性差异（P〈0．01）。对照组有16只眼（22．2％）暗环境下有眩光主述,波前组有5只眼（6．8％）,两组眩光症状比较,有统计学意义（P〈0．05）。结论波前引导与虹膜识别相结合的LASIK在治疗近视散光时,矫正的精确性明显优于常规LASIK,视觉质量更好。     

机械法-准分子激光上皮瓣下角膜磨镶术矫正中高度近视散光

目的探讨机械法一准分子激光上皮瓣下角膜磨镶术（Epi—LASIK）矫正中高度近视散光的临床疗效及影响因素。方法对散光等于和高于-1．00D的复性近视散光和单纯近视散光214例（417眼）运用Epi—LASIK矫正,顺规散光138例（270眼）,逆规散光46例（91眼）,斜向散光30例（56眼）。散光-1．00D～-3．00D者344眼,～3．00D- -6．00D者73眼。结果术后刺激症状轻微,314眼（76．29％）疼痛评分为0～1分。术后6月达到预期矫正视力者384眼（92．09％）,实际矫正散光度接近术前预测矫正散光度。角膜地形图由术前354眼（84．93％）对称蝴蝶结形和不对称蝴蝶结形,术后6个月321眼（77．14％）为圆形和椭圆。术后hase反应-1．00D～-3．00D和-3．00D以上两组对比,hase2级及2级以上差异有统计学意义（P〈0．01）。结论Epi—LASIK矫正中高度近视散光安全有效,haze反应轻,视觉质量好。     

人工虹膜识别定位技术在准分子激光原位角膜磨镶术中的应用

目的 探讨人工虹膜识别定位技术在准分子激光原位角膜磨镶术（LASIK）中的应用价值.方法 2008年3月至2010年1月在我院行LASIK术治疗的复合性近视散光患者314例（410眼）,分为两组：Ⅰ组162例（205眼）,年龄为18～35岁,散光度为-1.0～-3.0 D,球镜屈光度为-1.25～-4.75 D,LASIK术中采用人工虹膜识别定位技术;Ⅱ组152例（205眼）,年龄为18～40岁,散光度为-1.0～-2.5 D,球镜屈光度为-1.00～-5.50 D,同期行常规LASIK手术.人工虹膜识别定位方法：术前应用数码照相裂隙灯,照取水平细裂隙光带投照在虹膜瞳孔中央的清晰虹膜像,术中以该图像为依据来确定、标记术眼水平轴,激光治疗中始终保持该轴在视野中央并与手术显微镜中水平基准轴平行.术前、术后6个月,分别在电脑验光基础上应用综合验光方法测定散光度和轴向.采用SPSS 17.0统计软件,对两组术后残余散光度及轴向进行配对t检验.结果 两组手术均顺利完成,无LASIK相关并发症发生;术后恢复顺利,术后6个月内裸眼视力与预期相符,无明显不适主诉.Ⅰ组术后散光度为（-0.73±0.34）D,Ⅱ组术后散光度为（-0.68±0.53）D,两组差异无统计学意义（t=-1.200,P=0.231）;Ⅰ组术后散光轴向为（13.25±13.09）.,Ⅱ组为（17.48±17.93）.,两组差异有统计学意义（t=-2.755,P=0.006）.结论 人工虹膜识别定位技术在LASIK术中矫正散光及调整眼位有较好的应用价值,可在多种屈光手术中推广使用.     

实时虹膜识别在波前引导LASIK术中的应用价值

目的 评价实时虹膜识别技术在波前像差引导准分子激光原位角膜磨镶术（LASIK）中的价值。方法 随机对照研究。接受实时虹膜识别联合波前引导LASIK手术的近视患者50例（100眼）作为虹膜识别组,接受常规波前引导LASIK手术的近视患者51例（102眼）作为对照组,对两组患者术后1、3、6个月的裸眼视力、屈光度、高阶像差、对比敏感度等进行比较。采用配对t检验、成组t检验、方差分析和卡方检验。结果 术后6个月时,虹膜识别组最佳矫正视力提高1行以上的患者（62眼,62.0%）多于对照组（48眼,47.1%）,差异有统计学意义（x²=4.99,P＜0.05）;虹膜识别组的平均散光（-0.19±0.24）D低于对照组（-0.30±0.36）D,差异有统计学意义（t=2.49,P<0.05）。术后6个月,当瞳孔直径为6 mm时,虹膜识别组彗差、三叶草像差均方根值均小于对照组,差异均有统计学意义（t=2.22、3.31,P<0.05）。术后6个月对照组对比敏感度恢复到术前水平,而虹膜识别组略优于术前。结论 实时虹膜识别技术能够提高波前像差引导LASIK手术的视觉质量。     

Epi—LASIK和LASIK治疗近视散光的早期疗效对比观察

目的：探讨分析角膜微型刀上皮瓣下准分子激光原位角膜磨镶术（epipolislaserinsitukeratomileusis,Epi—LASIK）和准分子激光原位角膜磨镶术（1aserinsitukeratomileusis,LASIK）治疗近视散光的疗效。方法：近视散光行Epi—LASIK治疗的患者32例64眼,LASIK治疗的患者63例126眼,将患者根据柱镜度数分为2组：I组（柱镜-0．25～-2．75D,Epi—LASIK20例、LASIK48例）、II组（柱镜-3．00—-5．00D,Epi—LASIK12例、LASIK15例）。随访6too观察两种术式的疗效。对比两组患者的术后裸眼视力（uncorrectedvisualacuity,UCVA）、最佳矫正视力（bestcorrectedvisualacuity,BCVA）、残余散光度、角膜愈合情况、眼压及角膜地形图等。结果：术后6mo,Ⅱ组中UCVA较术前明显提高,Epi—LASIK为21眼（87．5％）,LASIK为19眼（63．3％）,两术式相比较差异有显著性（,=4．055,P〈0．05）;残余散光度Epi—LASIK为-0．41±0．30D,LASIK为-0．74_＋0．36D,两术式相比较差异有显著性（t=2．672,P〈0．05）;角膜散光Epi—LASIK为0．63±0．34D,LASIK为0．81±0．52D,两术式相比较差异有显著性（t=2．234,P〈0．05）。结论：Epi—LASIK治疗≥-3．00D散光与LASIK相比具有更好的效果和预测性。     

波前像差引导准分子激光原位角膜磨镶术治疗近视散光的疗效分析

目的比较波前像差引导准分子激光原位角膜磨镶术（laser in situ keratomileusis,LASIK）与传统LASIK术治疗中高度近视散光（柱镜-1．0D以上）的疗效。方法波前像差引导LASIK术治疗近视散光44例86眼作为试验组，同期接受常规LASIK术治疗者45例90眼作为对照组。比较术后第1天和3个月2组的裸眼视力、残留散光和高阶像差。结果试验组和对照组裸眼视力1．0以上者术后第1天分别为80眼和71眼（x^2=7．209，P〈0．01）；术后3个月分别为86眼和85眼（x^2=4．917，P〈0．05）。术后3个月裸眼视力1．2以上者分别为78眼和55眼（x^2=20．850。P〈0．01）。术后3个月，试验组残留散光（0．24±0．19）D，对照组残留散光（0．51±0．39）D（t=5．879，P〈0、01）；试验组和对照组总高阶像差的均方根值分别为0．591±0．272和0．721±0．231（t=3．410，P〈0．01）。结论对于中高度近视散光，波前像差引导的LASIK术较传统LASIK术治疗效果更好，具有视力恢复更快、术后视力更好、残留散光更少和高阶像差增加更少的优点。     

Wavefront-guided laser in situ keratomileusis with the Bausch & Lomb Zyoptix system

PURPOSE: To evaluate the clinical results of wavefront-guided laser in situ keratomileusis (LASIK) with the Zyoptix system. METHODS: Twelve patients (24 eyes) underwent wavefront-guided LASIK with the Bausch & Lomb Zyoptix system. Uncorrected and best spectacle-corrected visual acuity and manifest refraction were measured at postoperative day 1, week 1, and months 1 and 3. A subjective vision quality questionnaire evaluated light sensitivity, dryness, tearing, glare, halos, ghost images, and difficulties in night driving, preoperatively and 3 months postoperatively. RESULTS: Preoperatively, mean sphere was -3.70 +/- 2.33 D (range -0.50 to -8.00 D), mean cylinder was -0.90 +/- 0.98 D (range 0 to -3.00 D), and mean spherical equivalent refraction was -4.15 +/- 2.16 D (range -1.38 to -8.25 D). Three-month postoperative spherical equivalent refraction was within +/- 0.50 D of emmetropia in 17 eyes (70.8%) and within +/- 1.00 D in 22 eyes (91.7%). At 3 months postoperatively, no eyes lost any lines of BSCVA and eight eyes (33.3%) gained 2 lines. The ratio of postoperative BSCVA to preoperative BSCVA (safety) was 1.05 +/- 0.09 (range 1.00 to 1.20) at 1 month and 1.07 +/- 0.10 (range 1.00 to 1.29) at 3 months. The ratio of postoperative UCVA to preoperative BSCVA (efficacy) was 0.96 +/- 0.12 (range 0.80 to 1.20) at 1 month and 0.95 +/- 0.12 (range 0.8 to 1.2) at 3 months. The subjective vision quality questionnaire revealed less tearing, fewer halos, and less difficulty in night driving after wavefront-guided LASIK. Comparison of higher order optical aberrations before and after surgery was not done. CONCLUSIONS: Wavefront-guided LASIK with the Bausch & Lomb Zyoptix system was safe and effective in correcting low to moderate myopic refractive error.     

LASIK for post penetrating keratoplasty astigmatism and myopia

AIMS: To report the results of a series of patients who were treated with LASIK to correct post penetrating keratoplasty ametropia. METHODS: 26 eyes of 24 patients underwent LASIK to correct astigmatism and myopia after corneal transplantation; 14 eyes also received arcuate cuts in the stromal bed at the time of surgery. The mean preoperative spherical equivalent was -5.20D and the mean preoperative astigmatism was 8.67D. RESULTS: The results of 25 eyes are reported. The mean 1 month values for spherical equivalent and astigmatism were -0.24D and 2.48D respectively. 18 eyes have been followed up for 6 months or more. The final follow up results for these eyes are -1.91D and 2.92D for spherical equivalent and astigmatism. The patients undergoing arcuate cuts were less myopic but had greater astigmatism than those not. The patients receiving arcuate cuts had a greater target induced astigmatism, surgically induced astigmatism, and astigmatism correction index than those eyes that did not. One eye suffered a surgical complication. No eyes lost more than one line of BSCVA and all eyes gained between 0 and 6 lines UCVA. CONCLUSIONS: LASIK after penetrating keratoplasty is a relatively safe and effective procedure. It reduces both the spherical error and the cylindrical component of the ametropia. Correction of high astigmatism may be augmented by performing arcuate cuts in the stromal bed.     

The safety and efficacy of photorefractive keratectomy after laser in situ keratomileusis

PURPOSE: To determine the safety and efficacy of performing photorefractive keratectomy (PRK) in corneas previously treated with laser in situ keratomileusis (LASIK) surgery. METHODS: Fifteen eyes of 14 patients who had initially received LASIK for the treatment of myopia and compound myopic astigmatism were evaluated. Variables included existence of and/or type of flap complication associated with the original LASIK procedure, refractions before and after (3 and 6 months) PRK, uncorrected visual acuity (UCVA), best spectacle-corrected visual acuity (BSCVA), and the development of complications after PRK such as haze, scarring, double vision, or ghosting. RESULTS: All 15 eyes were available for analysis at 6 months. Eleven eyes had experienced flap complications during the initial LASIK procedure and 4 eyes had experienced complications in the LASIK postoperative period. Characteristics prior to performing PRK included 11 myopic and 4 hyperopic eyes. By 6 months after PRK treatment, 87% of eyes had UCVA > or = 20/40, 53% had > or = 20/25, and 40% had > or = 20/20. All eyes had BSCVA of > or = 20/30, with 73% being > or = 20/20. No eye had lost 2 lines of BSCVA and only 1 eye lost 1 line of BSCVA. Sixty percent of eyes were within 1.0 diopters (D) of emmetropia, and 40% were within 0.5 D of emmetropia. A trend towards undercorrection and surgical induction of astigmatism as confirmed by vector analysis was noted. No eye developed significant haze or scarring. CONCLUSIONS: Photorefractive keratectomy may be a safe procedure to perform in corneas previously treated with LASIK surgery. Results show good reduction of refractive error and improvement of UCVA and BSCVA. A significant undercorrection of astigmatism was attributed to surgically induced astigmatism. Further studies are necessary to determine the long-term safety and stability of outcomes.     

LASIK for myopia with the Zeiss meditec MEL 80

PURPOSE: To prospectively evaluate a new high-speed, small spot-scanner laser for the correction of myopia and myopic astigmatism. METHODS: Seventy-six consecutive eyes with myopia and myopic astigmatism between -1.00 and -8.25 diopters (D) and up to -2.75 D astigmatism underwent LASIK treatment using the MEL 80 laser (Carl Zeiss Meditec, Jena, Germany). Parameters evaluated were uncorrected visual acuity (UCVA), best spectacle-corrected visual acuity (BSCVA), residual refractive error, regression of correction, and aberrometry. RESULTS: Mean preoperative BSCVA was 20/20, which improved to 20/18 postoperatively. Postoperative UCVA was 20/20 at 1 month and 20/18 at 1 year. Uncorrected visual acuity > or = 20/20 was achieved in 58 (83%) of 70 eyes at 1 month and in 60 (88%) of 68 eyes at 1 year. The average refractive error before LASIK was -4.41 +/- 1.98 D. The mean residual refractive error was 0.14 +/- 0.31 D at 1 month and 0.13 +/- 0.30 D at 1 year. At 1-month and 1-year follow-up, respectively, 66 (94%) of 70 eyes and 65 (96%) of 68 eyes were within +/- 0.50 D of intended refractive correction. No eye lost two lines. At 1 month 17% of eyes and at 1 year 13% of eyes gained two lines or more. Between 1-month and 1-year follow-up, 100% of eyes were stable. Mean root-mean-square high order aberration changed from 0.20 microm preoperatively to 0.28 microm postoperatively. CONCLUSIONS: The MEL 80 is effective and safe in the treatment of myopia and myopic astigmatism.     

Nomogram adjustment of laser in situ keratomileusis for myopia and myopic astigmatism with the Alcon LADARVision system

PURPOSE: To evaluate the visual and refractive results of conventional (non-wavefront) laser in situ keratomileusis (LASIK) for treatment of myopia and myopic astigmatism using the Alcon LADARVision 4000 excimer laser system and nomogram adjustment techniques. METHODS: A retrospective analysis of 499 eyes that had LASIK for myopia and myopic astigmatism was performed. Preoperative manifest spherical equivalent refraction ranged from -0.43 to -6.00 D and preoperative astigmatism ranged from 0 to -4.75 D. Patients were evaluated during 3 months following surgery. RESULTS: One month after surgery, 72% of eyes examined (298/415 eyes) had uncorrected visual acuity (UCVA) of 20/20 or better. Three months after surgery, 83% of eyes examined (216/261 eyes) had UCVA of 20/20 or better. One and three months after surgery, 82% and 83% of eyes, respectively, were within +/-0.50 D of attempted correction; 97% of eyes were within +/-1.00 D at both 1 and 3 months. No eye lost more than 1 line of best spectacle-corrected visual acuity (BSCVA) at 3 months after surgery. At the 3-month examination, 83% of eyes had UCVA better than or equal to preoperative BSCVA. CONCLUSIONS: Conventional LASIK to correct myopia and myopic astigmatism was safe and effective using the Alcon LADARVision 4000 excimer laser system. Outcomes were substantially improved throughout development of an accurate nomogram, derived from continually updated regression analysis of previous refractive results.     

Laser in situ keratomileusis for compound myopic astigmatism using the Meditec MEL 70 G-Scan excimer laser

PURPOSE: To determine the safety, efficacy, predictability, and stability of laser in situ keratomileusis (LASIK) in treating patients with myopic astigmatism using the Meditec MEL 70 G-Scan excimer laser. METHODS: Seventy-four eyes of 42 patients with myopia ranging from -4.50 to -9.88 D and astigmatism ranging from 0.50 to 4.00 D who underwent LASIK with the Meditec MEL 70 G-Scan excimer laser and the Summit Krumeich-Barraquer microkeratome were studied. Patients were followed for 1 year. RESULTS: Mean baseline spherical equivalent refraction was -7.12 +/- 1.70 D and cylinder was 1.62 +/- 1.72 D. At 12 months, mean postoperative spherical equivalent refraction was -0.49 +/- 0.57 D and mean refractive cylinder was 0.59 +/- 0.32 D. Mean change in spherical equivalent refraction between 1 and 12 months after surgery was -0.09 +/- 0.31 D, toward myopia. At baseline, no eyes had best spectacle-corrected visual acuity (BSCVA) of 20/20 or better, and 65% had 20/40 or better. At 12 months after surgery, 10% of eyes had BSCVA of 20/20 or better and 88% of eyes had 20/40 or better. The unusually low postoperative BSCVA results were thought to be due to amblyopia or existence of a higher percentage of some optical aberrations in this group of eyes. Mean uncorrected visual acuity was -1.38 +/- 0.42 LogMAR units (20/400) at baseline and -0.29 +/- 0.25 LogMAR units (20/40) at the 12-month postoperative examination. No eyes lost two or more lines of spectacle-corrected visual acuity. No vision threatening complications were observed. CONCLUSIONS: LASIK with the Meditec MEL 70 G-Scan excimer laser appeared to be safe, effective, reasonably predictable, and stable for correction of myopic astigmatism with a spherical component between -4.25 and -8.25 D and a cylindrical component between 0.50 and 4.00 D. However, astigmatism was slightly undercorrected with the algorithm used.     

Astigmatic changes after excimer laser refractive surgery

PURPOSE: To compare the astigmatic changes induced by spherical and elliptical excimer laser in situ keratomileusis (LASIK) and photorefractive keratectomy (PRK). SETTING: University-based refractive surgery practice. METHODS: Three-month refractive data from 317 eyes of consecutive patients having spherical PRK, astigmatic PRK (A-PRK), spherical LASIK, and astigmatic LASIK (A-LASIK) by a single surgeon (J.S.P.) using VISX 2020B and Star lasers over 2 years were studied for astigmatic changes resulting from the surgical procedure. RESULTS: At 3 months, the mean change in absolute astigmatism was +0.15 diopter (D) and -0.07 D in the spherical PRK and LASIK groups, respectively. Photorefractive keratectomy tended to induce with-the-rule (WTR) astigmatism, while LASIK was astigmatically neutral. As expected, the eyes treated with A-PRK and A-LASIK achieved a greater reduction in absolute astigmatism (-1.02 D and -1.28 D, respectively) than those treated with spherical PRK and LASIK. The qualitative nature of the astigmatic change was different between flap-based and PRK-based procedures. CONCLUSIONS: Spherical PRK is more likely than spherical LASIK to induce astigmatism, with a tendency toward WTR astigmatism. The eyes treated with spherical LASIK had no preponderant change in the direction of astigmatic magnitude or axis. Astigmatic PRK and LASIK effectively reduced astigmatism along the preoperative axis; A-LASIK tended to induce a random resultant axis in most patients.     

Laser in situ keratomileusis for myopic astigmatism

PURPOSE: To evaluate the refractive results of laser in situ keratomileusis (LASIK) for myopic astigmatic eyes, and to assess the efficacy, accuracy, stability, and safety of the procedure. METHODS: LASIK was performed on 113 eyes of 73 patients for correction of myopic astigmatism ranging from 1.00 to 5.00 D, as measured by manifest refraction, with a mean baseline refractive astigmatism of 2.09 +/- 1.12 D. The Chiron Automated Corneal Shaper was used to create a corneal flap, and laser ablation was performed using the Chiron-Technolas Keracor 116 excimer laser. Follow-up time was 12 months for all eyes. RESULTS: Refractive astigmatism was stable by 3 months after surgery. At 1 year after LASIK, refractive astigmatism was reduced to a mean of 0.25 +/- 0.31 D (range 0 to 1.00 D). Sixty-one eyes (54%) had no residual astigmatism and 98 eyes (86.7%) had 0 to 0.50 D of refractive astigmatism. The mean percent reduction of preoperative astigmatism was 87.9 +/- 14.9%. The mean axis deviation of the surgically induced astigmatism was 2.1 +/- 3.1 degrees, with 96 eyes (84.9%) within 5 degrees of the desired axis. The percent correction of preoperative astigmatism in the proper axis was 97.1 +/- 15.5%. Spectacle-corrected visual acuity improved by 2 lines in 11 eyes (9.7%), and was reduced by 1 line only in 1 eye. There were no other significant complications. CONCLUSION: LASIK with the Chiron-Technolas Keracor 116 excimer laser was effective for correction of myopic astigmatism, with good stability after 3 months. The results were predictable with an acceptable degree of accuracy. LASIK is a safe procedure with very few complications.