Topographic- and wavefront-guided customized ablations with the NIDEK-EC5000CXII in LASIK for myopia

PURPOSE: To assess refractive outcomes, changes in the total higher order root mean square (RMS) aberration, and changes in higher order wavefront aberrations after LASIK for myopia and myopic astigmatism with the NIDEK Advanced Vision Excimer Laser platform (NAVEX) using either an aspheric or topography-based or whole eye wavefront ablation algorithm. METHODS: This was a retrospective study of 1459 eyes that underwent LASIK for myopia and myopic astigmatism. The mean preoperative spherical equivalent refraction was -4.68 diopters (D) (range: -0.50 to -9.63 D) with astigmatism up to -4.50 D. Treatments were classified into three categories depending on the type of ablation algorithm used--optimized aspheric transition zone (OATz) denoted eyes that underwent aspheric treatment zones; customized aspheric treatment zone (CATz) denoted eyes that underwent customized ablations based on corneal topography; and OPDCAT denoted eyes that underwent customized ablation based on the whole eye wavefront profile. Follow-up data are reported at 3 months (69%) and 12 months (17%) postoperatively. RESULTS: Three months after LASIK, the predictability (10.5 D from target refraction) was 80% for OATz, 91% for CATz, and 76% for OPDCAT. Of all eyes, 96% were within +/- 1.0 D of intended refraction 3 months postoperatively and 100% after 12 months (87% +/- 0.5 D). In the aspheric and custom groups, a notable improvement of uncorrected visual acuity was noted between 3 and 12 months after LASIK. No eye lost >1 line of best spectacle-corrected visual acuity. Mean higher order RMS increased in all groups. CONCLUSIONS: The data support that the treatment of myopia and myopic astigmatism is safe and effective with NAVEX. Customized ablation based on corneal topography rather than on total wavefront error was more predictable.     

Conventional vs wavefront-guided LASIK using the LADARVision4000 excimer laser

PURPOSE: To compare outcomes after LASIK surgery using the conventional LADARVision4000 laser and the wavefront-guided LADARWave CustomCornea wavefront system. METHODS: A prospective study was performed involving 140 myopic eyes receiving conventional or CustomCornea LASIK between May and October 2003. The preoperative manifest spherical equivalent refraction was limited to myopia < or = -7.00 diopters (D). The preoperative manifest cylinder was limited to < or = -2.50 D of astigmatism. Patients were evaluated for 3 months following surgery. Results evaluated were uncorrected visual acuity (UCVA), best spectacle-corrected visual acuity, manifest refraction, dilated wavefront measurements, contrast sensitivity, and patient responses to subjective questionnaires. RESULTS: For the CustomCornea eyes at 3 months, 80% (70/87) had UCVA > or = 20/20 and 95% (83/87) had UCVA > or = 20/25. For the conventional eyes at 3 months, 45% (9/20) had UCVA > or = 20/20 and 80% (16/20) had UCVA > or = 20/25. At the 3-month postoperative visit, 85% (74/87) of the CustomCornea eyes and 55% (11/20) of the conventional eyes were within +/- 0.50 D of their intended correction. At 1 and 3 months, the CustomCornea treated eyes had a statistically significant lower mean increase in higher order aberrations than conventionally treated eyes (P < .05). CONCLUSIONS: CustomCornea wavefront-guided LASIK surgery appears safe and effective and provides clinical benefits that appear to exceed those of conventional LADARVision surgery.     

Alcon CustomCornea wavefront-guided retreatments after laser in situ keratomileusis

PURPOSE: To evaluate the outcome of wavefront-guided ablations for the correction of residual myopia and astigmatism after standard laser in situ keratomileusis (LASIK). METHODS: Twenty nine eyes of 26 patients who underwent wavefront-guided LASIK retreatment with Alcon CustomCornea (Alcon Laboratories Inc, Fort Worth, Tex) were evaluated. Complete ophthalmologic examination, corneal topography, and wavefront measurements were performed. Uncorrected visual acuity (UCVA), best spectacle-corrected visual acuity (BSCVA), manifest refraction, and wavefront analysis were evaluated preoperatively, 1 week, 3 months, and 6 months after surgery. Wavefront measurements were assessed using the LADARWave device. Statistical analysis was performed using the McNemar test and percentages of success. RESULTS: One week postoperatively, UCVA was > or =20/40 in 100% of eyes (> or =20/20 in 31%) and BSCVA was > or =20/40 in 100% (> or =20/20 in 73%). Wavefront analysis showed a decrease in total aberrations, high order aberrations, defocus, coma, spherical aberration, and other terms of higher order aberrations at 1-week follow-up. Three months postoperatively, UCVA was > or =20/40 in 100% of eyes (> or =20/20 in 38%) and BSCVA was > or =20/40 in 100% (> or =20/20 in 81%). Six months postoperatively, UCVA was > or =20/40 in 100% of eyes (> or =20/20 in 60%) and BSCVA was > or =20/40 in 100% (> or =20/20 in 90%). Wavefront analysis showed decrease in total aberration, high order aberration, defocus, coma, and spherical aberration. CONCLUSION: Wavefront-guided LASIK retreatment in post-LASIK eyes represents a good option for laser vision correction. All eyes showed reduction in pre-existing total aberrations. Some high order aberration components decreased in this initial series. Further follow-up is necessary to assess the initial predictability of wavefront-guided LASIK upgrade.     

Visual outcomes of wavefront-guided laser in situ keratomileusis in eyes with moderate or high myopia and compound myopic astigmatism

PURPOSE: To evaluate the safety, efficacy, and clinical outcomes of wavefront-guided laser in situ keratomileusis (LASIK) surgery for the treatment of moderate to high myopia and compound myopic astigmatism. SETTING: Stanford University School of Medicine, Department of Ophthalmology, Stanford, California, USA. METHODS: This retrospective study included patients with moderate (-6.0 to -8.0 diopters [D]) and high (greater than -8.00) myopia treated with wavefront-guided LASIK using the WaveScan linked to the CustomVue system (AMO USA, Inc.). Eyes were analyzed preoperatively and 1, 3, and 12 months postoperatively. RESULTS: The mean patient age was 38.4 years +/- 7.14 (SD). Eighty-nine eyes of 45 patients were evaluated at 3 months and 50 eyes of 25 patients at 12 months. No eye was retreated during the study. The mean manifest refraction spherical equivalent was -8.10 +/- 0.98 D (range -6.00 to -10.63 D) preoperatively and -0.33 +/- 0.55 D (range -1.625 to 1.375 D) 12 months postoperatively. Ninety percent of the eyes were within +/-1.00 D of the intended correction and 64.0%, within +/-0.50 D. For all eyes, the safety index was 1.00 and the efficacy index, 1.18. CONCLUSION: The data support the safety and efficacy of correcting moderate to high myopia and compound myopic astigmatism using wavefront-guided LASIK.     

Clinical results of wavefront-guided laser in situ keratomileusis 3 months after surgery

PURPOSE: To investigate the visual and refractive outcome of wavefront-guided laser in situ keratomileusis (LASIK) to correct myopic astigmatism. SETTING: Departments of Ophthalmology of the Universities of Dresden, Dresden, Germany, and Zurich, Zurich, Switzerland. METHODS: This prospective study comprised 35 eyes of 28 patients who had a mean preoperative spherical refraction of -4.8 diopters (D) +/- 2.3 (SD) and a cylinder of -1.1 +/- 0.9 D. Preoperative and postoperative wavefront analysis was performed with a Tscherning aberrometer. A scanning-spot laser with a 1.0 mm spot size and a 200 Hz repetition rate was used. The eye-tracking system had a response time of less than 6 milliseconds. The treatment area diameter ranged from 6.0 to 7.0 mm with a transition zone of 1.0 mm. RESULTS: At 3 months, 68.0% of the eyes were within +/-0.5 D of emmetropia and 93.5% were within +/-1.0 D. Uncorrected visual acuity was 20/20 or better in 93.5% of eyes. No eye lost more than 1 line of low-contrast, glare, and best spectacle-corrected visual acuity (BSCVA). Supernormal vision (BSCVA of 20/10 or better) was achieved in 16.0% of eyes. The correction of higher-order aberrations (spherical aberration, coma) was insufficient, with an increase factor of the overall root-mean-square wavefront error of 1.44 +/- 0.74. Coma was better corrected than spherical aberration. CONCLUSIONS: Wavefront-guided LASIK is a promising technique that offers the potential to correct refractive errors, to improve visual acuity, and to increase the quality of vision, especially under mesopic conditions. Studies that include selective overcorrection of different Zernike components are needed to achieve better correction of the aberrations. Prospective controlled clinical studies must clarify the major benefits of wavefront-guided LASIK.     

Clinical outcome of wavefront-guided laser in situ keratomileusis in eyes with moderate to high myopia with thin corneas

PURPOSE: To evaluate the clinical outcome of wavefront-guided laser in situ keratomileusis (LASIK) for the treatment of moderate to high myopia associated with a thin cornea. SETTING: Enaim Laser Medical Center, Tel Aviv, Israel. METHODS: This retrospective study included 98 eyes of 49 patients with moderate to high myopia (-5.20 to -10.35 diopters [D]) and thin corneas (456 to 498 mum) treated with wavefront-guided LASIK (Zyoptix, Bausch & Lomb) and followed for 36 months. Preoperative wavefront analysis was performed with a Hartmann-Shack aberrometer, and treatment was performed with the Technolas 217 z excimer laser system (Bausch & Lomb). Final refraction data, uncorrected visual acuity (UCVA), best corrected visual acuity (BCVA), optic zone size, ablation depth, optical aberrations, and night glare complaints were evaluated. RESULTS: Mean patient age was 28 years +/- 7 (SD), and mean preoperative spherical equivalent refraction was -7.06 D (range -5.20 to -10.35 D). Final UCVA ranged between 6/6 and 6/30. The safety index of the technique was 1.03, and the efficacy index was 0.67. Undercorrection of more than 0.50 D was observed in 41.3% of the high-myopic eyes (-7.00 to -10.35 D, n = 58) compared with 10% in the moderately myopic eyes (-5.00 to -6.75 D, n = 40). A significant reduction in spherical aberration (Z(4)0) was found 12 months postoperatively in all eyes. Night glare was documented in 4 eyes (4%) in the high myopia group. There were no cases of corneal ectasia. CONCLUSION: Zyoptix was safe in eyes with moderate to high myopia with relatively thin corneas (<498 microm). For myopia between -7.00 D and -10.35 D, a small optical zone (4.3 to 5.6 mm) may be applied as night glare was relatively rare, but significant undercorrection should be expected.     

Total and corneal optical aberrations induced by laser in situ keratomileusis for hyperopia

PURPOSE: To evaluate changes induced by standard laser in situ keratomileusis (LASIK) for hyperopia on total and corneal optical quality. METHODS: Total and corneal aberrations were measured before and after standard hyperopic LASIK in 13 eyes (preoperative spherical equivalent refractive error +3.17 +/- 1.10 D). The Chiron Technolas 217C laser with PlanoScan was used. Total aberrations (measured using laser ray tracing) and corneal aberrations (estimated from a videokeratoscope) were described using Zernike terms. Root-mean-square wavefront error for both total and corneal aberrations, and through-focus Strehl ratio for the point spread function of the whole eye were used to assess optical changes induced by surgery. RESULTS: Third and higher order aberrations increased significantly after hyperopic LASIK (by a factor of 2.20 for total and 1.78 for corneal aberrations, for a 6.5-mm pupil). Spherical aberration changed to negative values (corneal average decreased by -0.85 +/- 0.48 microm and total average by -0.70 +/- 0.30 microm). Best Strehl ratio for the whole eye decreased by a factor of 1.84. Hyperopic LASIK induced larger changes than myopic LASIK, compared to an equivalent group of myopic eyes from a previous study. Induced corneal spherical aberration was six times larger after hyperopic LASIK, for a similar range of correction, and of opposite sign. As with myopic LASIK, changes in internal spherical aberration are of opposite sign to those induced on the corneal anterior surface. CONCLUSIONS: Hyperopic LASIK induced significant amounts of aberrations. The largest increase occurred in spherical aberration, which showed a shift (toward negative values) of opposite sign; increase was greater than for myopic LASIK.     

Customized LASIK treatment for myopia: relationship between preoperative higher order aberrations and refractive outcome

PURPOSE: To analyze the effect of preoperative higher order aberrations on postoperative sphere and cylinder outcome. METHODS: Three hundred thirty myopic eyes (mean: -3.32 +/- 1.54 diopters [D], range: -1.0 to -7.0 D) treated with customized ablation using the Technolas 217z laser (Bausch & Lomb) were followed through 6 months after LASIK. Pre- and postoperative visual acuity, higher order root mean square (RMS), third order RMS, and spherical aberration were compared to study the safety and efficacy of the treatment. The relationship between preoperative higher order aberrations and manifest refraction after LASIK was analyzed. RESULTS: Following LASIK, 91.5% of eyes obtained an uncorrected visual acuity of > or = 20/20 and 70.3% of eyes obtained 20/16 without retreatment; 99% had a best spectacle-corrected visual acuity of > or = 20/20 (75.9% of eyes were within +/- 0.50 D). Mean value of significant increase in postoperative higher order aberrations was 0.12 +/- 0.18 microm (P<.0001). Increased spherical aberration was associated with increased myopia treatment (P<.0001). Greater positive spherical aberration after LASIK was significantly correlated to postoperative hyperopia (overcorrection). Change in third order RMS was significantly correlated to change in spherical equivalent refraction among eyes with postoperative astigmatism (P<.0001). CONCLUSIONS: With the Bausch & Lomb Technolas 217z Zyoptix software, treatment of higher order aberrations, especially third order (coma and trefoil) and spherical aberration, significantly improved postoperative refractive status.     

Correction and induction of high-order aberrations after standard and wavefront-guided LASIK and their influence on the postoperative contrast sensitivity

BACKGROUND: Wavefront-guided LASIK-treatments should reduce high-order aberrations (HOA). However, both the microkeratome cut as well as the ablation itself induce HOA. The purpose of this study was to investigate the amount of corrected preoperative measured HOA and induction of new HOA. METHODS: In this retrospective study 67 eyes of 45 myopic patients (- 2 to - 8.1 D SE; spherical equivalent) were treated by standard and wavefront-guided LASIK (Keracor 217z). Pre- and postoperative measurements of total aberrations and contrast sensitivity were performed. The follow-up time was 5.7 +/- 0.9 months. RESULTS: Patients with preoperative increased aberrations of 3rd and 4th order and myopia up to 5 D showed a slightly reduction of wavefront deformation. Cases of higher myopic corrections and lower preoperative spherical aberrations developed an increase of spherical aberrations after LASIK. The changes of other HOA showed no correlation with the amount of corrected myopia. Up to - 5 D patients showed the trend to better postoperative contrast sensitivity under 3 and 85 cd/m (2) after wavefront-guided LASIK than after standard LASIK. A significant advantage of wavefront-guided LASIK can be detected under a spatial frequency of 3 CPD (cycles per degree) and 85 cd/m (2). No advantages of any treatment procedure were shown after higher myopic corrections. CONCLUSION: If preoperative aberrations of 3rd and 4th order were increased and the myopia is < 5 D (SE) -- wavefront-guided LASIK can reduce total ocular HOA. Aberrometric findings after wavefront-guided LASIK in patients with lower preoperative HOA and myopia > 5 D (SE) are comparable with the results after standard treatment.     

LADARWave wavefront measurement in normal eyes

PURPOSE: We evaluated the correlation of Alcon LADARWave wavefront measurements with clinical refraction and corneal topography. METHODS: In a retrospective, non-comparative case series, 60 eyes (30 patients) of healthy individuals evaluated by preoperative examination for refractive surgery were enrolled (manifest sphere, -11.00 to +4.50 D; manifest cylinder, 0 to -4.75 D; 45 eyes were myopic, 12 eyes were hyperopic, and 3 had mixed astigmatism). Correlation of manifest refraction, cycloplegic refraction, and topographic data with wavefront refraction and higher order aberration was assessed. Match percentage given by the wavefront was analyzed. This number represents how much of the wavefront refraction is due to sphere and cylinder (high percentage match) or is influenced by higher order aberration (low percentage match), in which case aberrometer refraction will not be close to phoropter refraction. Pearson's correlation coefficient was assessed for two continuous variables, adjusting for repeated measurements. RESULTS: The median match percentage was 91%. Mean values for all higher order aberration components in a 7.0-mm pupil were: coma = 0.35 +/- 0.29 microm, spherical aberrations = 0.36 +/- 0.31 microm, and other terms of higher order aberrations = 0.31 +/- 0.14 microm. Wavefront sphere, cylinder, and axis terms were highly correlated to manifest and cycloplegic measurements. The high match subgroup had a higher correlation coefficient than the low match subgroup for refraction. Topographic cylinder and axis were not strongly correlated to wavefront refraction, but manifest axis was significantly correlated to topographic axis. CONCLUSION: In 60 normal eyes, the Alcon LADARWave wavefront measurement was highly correlated with refraction, but less well with corneal topography.     

近视眼患者波前像差的分析研究

目的：对近视眼患者存在的波前像差进行相关因素分析。 方法：用波前像差仪对前来我院行LASIK手术的115例218眼进行波前像差的检查,并进行常规角膜屈光手术的各项术前检查,同时用对比敏感度检查表进行对比敏感度的检查,将各项结果分别与波前像差进行相关性分析。 结果：像差成分以低阶像差为主,高阶像差有明显的个体差异,最大值是最小值的62倍;术前像差和瞳孔直径呈正相关关系,即随着瞳孔直径的增加高阶像差增加;高阶像差与中频区对比敏感度存在弱的负相关性;波前像差和患者的屈光度的高低有关系;随着散光度数的增加,波前像差增加。术前像差各成分和性别无显著相关性。 结论：近视眼患者的波前像差受患者具体条件的影响,个性化手术去除波前像差应考虑周全。     

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）     

虹膜定位对波前像差引导的LASIK效果影响

目的 探讨虹膜定位成功与否,对波前像差引导的准分子激光角膜原位磨镶术(LASIK)后的临床效果是否具有影响.方法 行CustomVueTM波前像差引导的LASIK手术单眼虹膜定位成功的近视患者31例62只眼.分别在术前和术后进行视力、屈光度和波前像差等检查,并进行双眼比较.结果 虹膜定位成功眼与未成功眼的术前检查无显著性差异.两组的术后视力分组无显著性差异(P＞0.05).虹膜定位成功眼的术后屈光度的可预测性略高于未成功眼.两组术眼的术后高阶像差RMS值均高于术前.其中术后球差均高于术前(P均＜0.01),但对于彗差和二级散光,IR成功组的术后和术前无显著性变化,而在IR未成功组术后测量值明显高于术前.IR成功组的术后彗差增加值低于IR未成功组(P＜0.05),其余各项指标两组之间无显著性差异(P＞0.05).结论 虹膜定位技术应用于波前像差引导的IASIK手术,可防止术后彗差的增加,但对其他临床结果尚未发现明显影响.     

常规LASIK与波前像差引导的LASIK治疗中高度近视散光的对比研究

目的 比较常规准分子激光原位角膜磨镶术（简称常规LASIK）和波前像差引导的个体化LISIK（简称波前像差引导LASIK）矫正中高度近视散光后的视觉质量.方法 随机选取2011年1月至2012年12月在我院行准分子激光手术者,其中散光度数≥-2.00 DC作为入选对象共82例（163只眼）.其中选择行波前像差引导的LASIK术者42例（83只眼）,散光（-3.55±1.09） DC;接受常规LASIK术者40例（80只眼）,散光（-3.47±1.23） DC.所有患者术前与术后7 d、1个月、6个月分别进行视力、角膜地形图、波前像差的检查和视疲劳满意度调查,比较两组的差别.结果 （1）术后7 d、1个月、6个月波前像差引导的LASIK术者视力分别优于常规LASIK术者（P＜0.05）.（2）角膜地形图查残余角膜散光度：波前像差组7 d、1个月、6个月分别为（-0.35±0.24） DC、（-0.42±0.13） DC、（-0.51±0.19） DC;常规组7 d、1个月、6个月分别为（-0.75±0.28） DC、（-0.92±0.23） DC、（-1.21±0.21） DC,两组差异有统计学意义（P＜0.05）.（3）波前像差组和常规组高阶像差均呈增加趋势,以彗差和球差增加为主.波前像差组在总高阶像差（HOAROM）、30°三叶草（Z6）、垂直彗差（Z7）和水平彗差（Z8）高阶像差的改变显著优于常规组（P＜0.05）.（4）视疲劳满意度调查：波前像差组明显优于常规组.结论 波前像差引导的个性化LASIK较常规LASIK能更好地矫正中高度近视散光,使患者术后角膜残余散光更少,高阶像差的增加更少,视力恢复更理想,视觉质量更佳,患者的满意度更好.     

Comparison of Collamer toric implantable [corrected] contact lens implantation and wavefront-guided laser in situ keratomileusis for high myopic astigmatism

PURPOSE: To compare the postoperative visual outcomes after implantation of a Collamer toric implantable contact lens (ICL) and after wavefront-guided laser in situ keratomileusis in high myopic astigmatism. SETTING: Department of Ophthalmology, Kitasato University, Kanagawa, Japan. METHODS: This study comprised 30 eyes (18 patients) having toric ICL implantation and 24 eyes (17 patients) having wavefront-guided LASIK (Technolas 217z) to correct high myopic astigmatism (manifest spherical equivalent [SE] or=1.0 D). The safety, efficacy, predictability, stability, and adverse events were assessed preoperatively and 1 week and 1, 3, and 6 months postoperatively. RESULTS: At 6 months, the mean safety index was 1.28+/-0.25 (SD) in the ICL group and 1.01+/-0.16 in the LASIK group and the mean efficacy index, 0.87+/-0.15 and 0.83+/-0.23, respectively. All eyes in the ICL group and 71% of eyes in the LASIK group were within +/-1.00 D of the targeted SE correction at 6 months. The mean change in manifest refraction from 1 week to 6 months was -0.04+/-0.24 D in the ICL group and -0.60+/-0.49 D in the LASIK group. There were no significant complications in the ICL group; 2 eyes (8.3%) in the LASIK group required enhancement ablations. CONCLUSION: Toric ICL implantation was better than wavefront-guided LASIK in eyes with high myopic astigmatism in almost all measures of safety, efficacy, predictability, and stability, suggesting that toric ICL implantation may become a viable surgical option to treat high myopic astigmatism.     

Prospective randomized comparison of wavefront-guided and conventional photorefractive keratectomy for myopia with the meditec MEL 70 laser

PURPOSE: To study refractive results and aberrometric changes in myopic patients treated with wavefront-guided photorefractive keratectomy (PRK) in comparison with standard PRK. METHODS: Sixty eyes of 60 patients with myopic astigmatism were randomly divided into two groups. Group 1 included 30 eyes (mean spherical equivalent refraction -4.39 +/- 1.31 D; range -2.50 to -6.50 D) treated with wavefront-guided PRK using the WASCA workstation and the Asclepion Meditec flying spot MEL 70 excimer laser. Group 2 had 30 eyes (mean spherical equivalent refraction -4.33 +/- 1.22 D; range -2.50 to -6.50 D) that underwent conventional PRK using the same laser, and served as the control group. Wavefront analysis of high order aberrations was performed before and 6 months after surgery. RESULTS: Postoperatively, wavefront error increased in both groups (5.0-mm wavefront aperture diameter). Six months after surgery, the eyes that received the WASCA ablation had a smaller increase in root-mean-square (RMS; 70% of increment) compared to the conventional PRK group (139% of increment) (P<.001). In the standard PRK group, all aberrations notably increased; in the wavefront-guided PRK group there was a smaller increase of trefoil and spherical aberrations (P<.001) and a decrease of coma aberrations (P<.001). The smaller increase of wavefront error in the wavefront-guided PRK group compared to the standard PRK group was more evident when preoperative RMS values were higher than 0.4 microm (P<.01). The visual parameters (spherical equivalent refraction, uncorrected and best spectacle-corrected visual acuity) did not show significant differences between the two groups. CONCLUSION: Wavefront-guided PRK induced a smaller increase of postoperative wavefront-error compared to conventional PRK, particularly in patients with higher preoperative higher order aberrations.     

Laser in situ keratomileusis for the correction of myopia and myopic astigmatism

PURPOSE: To evaluate the efficacy, safety, predictability, and surgically induced astigmatism (SIA) of laser in situ keratomileusis (LASIK) for the correction of myopia and myopic astigmatism. SETTING: Department of Ophthalmology, National Taiwan University Hospital, Taipei, Taiwan. METHODS: This retrospective study comprised 69 eyes that had LASIK to correct myopia and 74 eyes that had LASIK to correct myopic astigmatism. The excimer laser keratectomy was performed using a Summit Apex Plus machine. Refraction, visual acuity, and computerized corneal videokeratography data from the preoperative and postoperative examinations were collected. The astigmatic change was calculated by the Alpins vector analysis method. RESULTS: The preoperative spherical equivalent at the glasses plane in the myopia and myopic astigmatism groups was -8.08 diopters (D) and -9.73 D, respectively. At 6 months, the spherical equivalent and residual corneal astigmatism were -0.25 D and 0.85 D, respectively, in the myopia group and -0.71 D and 0.82 D, respectively, in the myopic astigmatism group. In the myopia group, 88% of eyes were within +/-1.0 D of the intended myopia correction and in the myopic astigmatism group, 85% were within +/-1.0 D of the targeted spherical equivalent and 90% were within +/-1.0 D of the intended astigmatism correction. The uncorrected visual acuity was 20/40 or better in 94.1% of eyes in the myopia group and 92.5% of eyes in the myopic astigmatism group. The SIA magnitude was 0.66 D with the axis randomly distributed in the myopia group. The mean astigmatism correction index was 0.97, the mean magnitude of error was 0.13 D +/- 0.62 (SD), and the mean angle of error was -3.70 +/- 13.73 degrees in the myopic astigmatism group. CONCLUSION: Laser in situ keratomileusis had similar predictability, safety, and efficacy in the treatment of myopia and myopic astigmatism. The astigmatism correction was effective, but the results suggest that subjective astigmatism of less than 1.0 D need not be treated with the Summit Apex Plus laser.     

Zyoptix wavefront-guided versus standard photorefractive keratectomy (PRK) in low and moderate myopia: randomized controlled 6-month study

PURPOSE: To evaluate the refractive and aberrometric outcome of wavefront-guided photorefractive keratectomy (PRK) compared to standard PRK in myopic patients. METHODS: Fifty-six eyes of 56 patients were included in the study and were randomly divided into two groups. The study group consisted of 28 eyes with a mean spherical equivalent (SE) of -2.25+/-0.76 diopters (D) (range: -1.5 to -3.5 D) treated with wavefront-guided PRK using the Zywave ablation profile and the Bausch & Lomb Technolas 217z excimer laser (Zyoptix system) and the control group included 28 eyes with a SE of -2.35+/-1.01 D (range: -1.5 to -3.5 D) treated with standard PRK (PlanoScan ablation) using the same laser. A Zywave aberrometer was used to analyze and calculate the root-mean-square (RMS) of total high order aberrations (HOA) and Zernike coefficients of third and fourth order before and after (over a 6-month follow-up period) surgery in both groups. Preoperative and postoperative SE, un-corrected visual acuity (UCVA), and best-corrected visual acuity (BCVA) were evaluated in all cases. RESULTS: There was a high correlation between achieved and intended correction. The differences between the two treatment groups were not statistically significant for UCVA, BCVA, or SE cycloplegic refraction . Postoperatively the RMS value of high order aberrations was raised in both groups. At 6-month control, on average it increased by a factor of 1.17 in the Zyoptix PRK group and 1.54 in the PlanoScan PRK group (p=0.22). In the Zyoptix group there was a decrease of coma aberration, while in the PlanoScan group this third order aberration increased. The difference between postoperative and preoperative values between the two groups was statistically significant for coma aberration (p=0.013). No statistically significant difference was observed for spherical-like aberration between the two groups. In the study group eyes with a low amount of preoperative aberrations (HOA RMS lower than the median value; <0.28 microm) showed an increase of HOA RMS while eyes with RMS higher than 0.28 microm showed a decrease (p<0.05). CONCLUSIONS: Zyoptix wavefront-guided PRK is as safe and efficacious for the correction of myopia and myopic astigmatism as PlanoScan PRK. Moreover this technique induces a smaller increase of third order coma aberration compared to standard PRK. The use of Zyoptix wavefront-guided PRK is particularly indicated in eyes with higher preoperative RMS values.     

Laser in situ keratomileusis for myopic astigmatism with the Nidek EC-5000 laser

PURPOSE: We studied the efficacy, predictability, and safety of laser in situ keratomileusis (LASIK) for moderate to high simple and compound myopic astigmatism. METHODS: Ninety-two eyes of 46 consecutive patients who had LASIK for myopic astigmatism (64 eyes, astigmatism 3.00 to 9.00 D; myopia 0 to -20.00 D), or simple myopia (28 eyes, myopia -4.00 to -20.00 D; astigmatism 0 to 0.50 D) were retrospectively studied. Mean baseline spherical equivalent refraction (SE) in the myopia group was -8.11 +/- 3.94 D and in the astigmatism group, -8.55 +/- 4.49 D. All eyes underwent LASIK using the Nidek EC-5000 laser by the same surgeon. RESULTS: At 6 months after LASIK in the myopia group versus the astigmatism group, 24 eyes (85%) vs. 54 eyes (84%) were available for follow-up, 12 eyes (50%) vs. 13 eyes (24%) had uncorrected visual acuity (UCVA) of 20/20, 19 eyes (79%) vs. 44 eyes (81%) had UCVA of 20/40, 8 eyes (33%) vs. 18 eyes (33%) had SE within +/- 0.50 D, 15 eyes (62%) vs. 39 eyes (72%) had SE within +/- 1.00 D, and mean SE was -1.22 +/- 1.17 D vs. -0.74 +/- 1.46 D. Mean astigmatism (vertexed to the corneal plane) in the astigmatism group was 2.77 D at 0 degrees before surgery and 0.32 D at 7 degrees at 6 months. None of the myopic eyes and three of the astigmatic eyes (5%) lost > or = 2 lines of best spectacle-corrected visual acuity. CONCLUSION: LASIK with the Nidek EC-5000 laser for myopic astigmatism was reasonably effective, predictable, and safe. Astigmatism was under-corrected with the nomogram implemented in this study.     

Clinical outcomes of wavefront-guided laser in situ keratomileusis: 6-month follow-up

PURPOSE: To evaluate the clinical outcomes 6 months after wavefront-guided laser in situ keratomileusis (LASIK) for myopia in Japan. SETTING: Department of Ophthalmology, Sanno Hospital, Tokyo, Japan. METHODS: This prospective study comprised 22 eyes of 12 patients treated with wavefront-guided LASIK who were available for evaluation at 6 months. The mean patient age was 31.2 years +/- 8.4 (SD) (range 23 to 50 years), and the mean preoperative spherical equivalent refraction was -7.30 +/- 2.72 diopters (D) (range -2.75 to -11.88 D). In all cases, preoperative wavefront analysis was performed with a Hartmann-Shack aberrometer and the Technolas 217z flying-spot excimer laser system (Bausch & Lomb) was used with 1.0 mm and 2.0 mm spot sizes and an active eye tracker with a 120 Hz tracking rate. The clinical outcomes of wavefront-guided LASIK were evaluated in terms of safety, efficacy, predictability, stability, complications, and preoperative and postoperative aberrations. RESULTS: At 6 months, 10 eyes had no change in best spectacle-correct visual acuity and 10 gained 1 or more lines. The safety index was 1.11 and the efficacy index, 0.82. Slight undercorrections were observed in highly myopic eyes. In all eyes, the postoperative refraction tended slightly toward myopia for 3 months and stabilized after that. No complication such as epithelial ingrowth, diffuse lamellar keratitis, or infection was observed. Comparison of the preoperative and postoperative aberrations showed that 2nd-order aberrations decreased and higher-order aberrations increased. In the 3rd order, aberrations increased in the high-myopia group (-6.0 D or worse) and decreased in the low to moderate-myopia group (better than -6.0 D). CONCLUSION: Wavefront-guided LASIK was a good option for refractive surgery, although a longer follow-up in a larger study is required.