Excimer laser keratectomy for correction of astigmatism

We treated 13 eyes (12 patients) with excimer laser surgery for correction of astigmatism using linear corneal T-excisions. All eyes were followed up for a minimum of three months. We used a newly developed delivery system and special contact masks to deliver the 193-nm excimer light. Astigmatic corrections of up to 4.16 diopters were obtained. The actual corrections corresponded well with the intended values as predicted by a biomechanical theory. The refractive change over time was different than that observed after knife incisions, suggesting different repair mechanisms. An epithelial plug filling the whole T-excision persisted for over one year in all eyes.     

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.     

Q值调整个性化在LASIK治疗中高度散光效果分析

目的 探讨Q值调整的个性化准分子激光原位角膜磨镶术(F-CAT)治疗中高度散光的安全性和有效性.方法 采用德国Wavelight公司的鹰视酷眼准分子激光系统,对36例(53只眼)中高度散光进行F-CAT手术治疗,术前等值柱镜度数-2.00～-6.00D,平均(-2.65±0.93)D.结果 术后12个月的平均裸眼视力为1.01±0.24,裸眼视力达到或超过术前矫正视力48只眼(90.6%).术后散光度较术前明显改善,除2只眼因角膜厚度所限,分别残留-1.5D、-1.75D散光,其余患者术后1年复查散光度均＜1 D,且一直较为稳定.术前Q值介于-0.05～-0.50,其中Q1值-0.29±0.10,Q2值0.33±0.12.目标Q值-0.15～-0.45,平均-0.29±0.09.术后12月角膜中央30度范围内Q值与术前球镜和柱镜之和相关性较强 .结论 F-CAT治疗中高度散光安全有效,视觉质量较好.     

Correction of astigmatism with the Excimer laser

Excimer laser corneal T-excisions for the correction of astigmatism in eight eyes followed up for three months postoperatively revealed an effective change in refraction of up to 4.2 diopters. The effect depends on the depth of the excision. Although the clinical results agree with astigmatism theory predictions from a biomechanical model of the cornea, some features are not explained by the model. The temporal behavior of the changes in refraction subsequent to excimer laser excisions differ from those produced by blade incisions, indicating a different repair mechanism. The keratectomy technique employed did not result in any serious side effects.     

Q-factor customized ablation profile for the correction of myopic astigmatism

PURPOSE: To compare the results of the Q-factor customized aspheric ablation profile with the wavefront-guided customized ablation pattern for the correction of myopic astigmatism. SETTING: Institute for Refractive and Ophthalmic Surgery, Zurich, Switzerland. METHODS: Thirty-five patients were enrolled in a controlled study in which the nondominant eye was treated with the Q-factor customized profile (custom-Q study group) and the dominant eye was treated with wavefront-guided customized ablation (control group). Preoperative and 1-month postoperative high-contrast visual acuity, low-contrast visual acuity, and glare visual acuity, as well as aberrometry and asphericity of the cornea, were compared between the 2 groups. All eyes received laser in situ keratomileusis surgery, and the laser treatment was accomplished with the Wavelight Eye-Q 400 Hz excimer laser. RESULTS: For corrections up to -9 diopters (D) of myopia, there were no statistically significant differences between the 2 groups regarding any visual or optical parameter except coma-like aberrations (3rd Zernike order), where the wavefront-guided group was significantly better 1 month after surgery (P = .002). For corrections up to -5 D (spherical equivalent), the Q-factor optimized treated eyes had a significantly smaller shift toward oblate cornea: DeltaQ15 = 0.25 in Q-factor customized versus DeltaQ15 = 0.38 in wavefront-guided treatment (P = .04). CONCLUSIONS: Regarding safety and refractive efficacy, custom-Q ablation profiles were clinically equivalent to wavefront-guided profiles in corrections of myopia up to -9 D and astigmatism up to 2.5 D. Corneal asphericity was less impaired by the custom-Q treatment up to -5 D of myopia.     

Excimer laser correction of post-traumatic corneal astigmatism on an "artiphakic" eye

A unique clinical case is presented: LASIK in a 12-year-old child for correction of posttraumatic corneal astigmatism after penetrating wound of the eye and extraction of traumatic cataract with IOL implantation. The patient was observed for 3 months postoperation.     

Excimer laser photorefractive keratectomy for high myopia and myopic astigmatism.

BACKGROUND AND OBJECTIVE: To determine the efficacy, safety, and predictability of excimer laser photorefractive keratectomy of high myopia and myopic astigmatism. PATIENTS AND METHODS: 76 eyes of 52 patients with myopia from -8.00 to -23.50 diopters (D) with or without astigmatism up to -5.50D were treated with the VISX 20/20 excimer laser (VISK, Santa Clara, CA) and a multi-zone ablation technique. Visual acuity, manifest refraction, corneal haze, and topography were evaluated at 1 week and 1, 3, 6, 12, and 18 months postoperatively. RESULTS: Postoperative refractions were generally stable after 12 months. At the last follow-up all patients were within - 1.96 D of the intended correction. Eighteen months postoperatively, 68% of patients undergoing photorefractive keratectomy (PRK), and 65% of patients undergoing photo astigmatic refractive keratectomy (PARK), were within 1 D of planned refraction. Furthermore, 87% of patients after PRK and 80% of patients after PARK had a visual acuity of 20/40 or better. CONCLUSIONS: High myopia with or without astigmatism was successfully treated in most of the patients using PRK. The stability of the postoperative refraction during the first 18 months seems to be good. The incidence of adverse effects was low but improvements in the future should further reduce complications, thus increasing the safety of refractive procedures.     

准分子激光角膜表层切削术矫治疑似圆锥角膜的长期临床观察

目的 探讨准分子激光上皮瓣下角膜磨镶术（LASEK）及机械法准分子激光上皮瓣下角膜磨镶术（Epi-LASIK）矫治疑似圆锥角膜引起的近视及散光的长期安全性、有效性和稳定性.方法 回顾性病例系列研究.疑似圆锥角膜患者38例（55眼）,年龄19～44岁,男7例,女31例.近视度-3.25～-7.75 D,平均（-5.54±2.18）D;散光度0～3 D,平均（0.80±0.75）D;中央角膜厚度479～605μm,平均（541.8±30.0）μm.角膜地形图均提示1期圆锥角膜,近视及散光度、角膜地形图形态稳定至少2年.55眼均成功接受了LASEK（38眼）或Epi-LASIK（17眼）.术后6个月及2年以上（2～5年）随访,检查患者的视力、屈光度及角膜地形图.对手术前后的数据进行配对t检验（正态分布）或Wilcoxon Signed Ranks检验（非正态分布）.结果 术后2年以上,48眼（87.3%）的裸眼视力≥1.0,有效指数为1.002;51眼（92.7%）的最佳矫正视力较术前不变或提高,仅4眼（7.3%）下降1行,安全指数为1.053;等效球镜度为（-0.11±0.45）D,在±0.50 D范围内为49眼（89.1%）,在±1.00 D范围内为53眼（96.4%）;近视度和散光度分别为（-0.01±0.45）D和（0.25±0.33）D.术后2年以上的近视及散光度与术后6个月比较,差异均无统计学意义（P＞0.05）.术后2年以上的角膜地形图圆锥角膜指数KI值为1.02±0.04,较术前（1.08±0.01）降低,差异有统计学意义（Z=-6.098,P＜0.01）.随访期间未见明显haze及圆锥角膜进展.结论 疑似圆锥角膜患者的年龄、近视屈光度、角膜厚度及屈光度和角膜地形图的稳定性是其能否接受LASEK或Epi-LASIK治疗的关键.LASEK和Epi-LASIK对于矫治屈光及角膜地形图形态稳定的疑似圆锥角膜的近视及散光,可能是一种安全、有效的方法,但更长期的安全性有待于进一步的观察.     

One year results of presbyLASIK using hybrid bi-aspheric micro-monovision ablation profile in correction of presbyopia and myopic astigmatism

AIM: To observe the effect of inhibiting lncRNA MALAT1 on diabetic neurodegeneration. METHODS: Thirty-six 8-week-old C57BL/6 mice were randomly divided into normal control, diabetic control, diabetic scrambled siRNA and diabetic MALAT1-siRNA groups. After diabetic induction with streptozocin intraperitoneally-injection, the diabetic MALAT1-siRNA group was intravitreally injected with 1 μL 20 μmol/L MALAT1 siRNA, and the diabetic scrambled siRNA group was injected with the same amount of scrambled siRNA. Electroretinography was performed to examine photoreceptor functions 16wk after diabetes induction. MALAT1 expression was detected via RT-PCR. Cone morphological changes were examined using immunofluorescence. Rod morphological changes were examined by determining outer nuclear layer thickness. RESULTS: Retinal MALAT1 expression was upregulated in the diabetic control group, while MALAT1 expression in the diabetic MALAT1-siRNA group was decreased by 91.48% compared to diabetic control group. The diabetic control and diabetic MALAT1-siRNA groups showed lower a-wave and b-wave amplitudes than did the normal control group in scotopic and photopic electroretinogram, while the diabetic MALAT1-siRNA group showed higher amplitudes than diabetic control group. Morphological examination revealed that outer nuclear layer thickness in the diabetic MALAT1-siRNA and diabetic control groups was lower than normal control group. However, outer nuclear layer thickness was greater in the diabetic MALAT1-siRNA group than diabetic control group. Moreover, the diabetic control group showed a sparser cone cell arrangement and shorter outer segment morphology than diabetic MALAT1-siRNA group. CONCLUSION: Inhibiting retinal MALAT1 results in protective effects on the function and morphology of photoreceptors, thus alleviating diabetic neurodegeneration.     

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。     

One-year results of laser vision correction for low to moderate hyperopia

OBJECTIVE: To assess the efficacy and safety of hyperopic laser vision correction using a refined ablation architecture and the VISX STAR Excimer Laser. DESIGN: Prospective noncomparative case series. PARTICIPANTS: Fifty-two eyes with hyperopia from +1 to +6 diopters (D) spherical equivalent (SE) with or without cylinder < or =1.5 D based on cycloplegic refraction. Hyperopia was primary or caused by prior overcorrection of myopia. INTERVENTION: Hyperopic laser vision correction using a 9 mm/5 mm ablation profile and a pulse rate of 10 Hz. We prescribed ciprofloxacin and fluorometholone four times a day for 1 week. MAIN OUTCOME MEASURES: SE; uncorrected visual acuity (UCVA); predictability within +/- 0.5 D, +/- 1.0 D, and +/- 2.0 D of target refraction (emmetropia); loss of best-corrected visual acuity (BCVA); haze, and all complications at 1, 3, 6, and 12 months. RESULTS: We treated 52 eyes (mean preoperative SE; +3.03 D). Forty-one eyes (78.8%) had primary hyperopia. At 3, 6, and 12 months, 66%, 67%, and 79% of all eyes had refraction within +/-0.5 D of emmetropia. At these same intervals, 83%, 88%, and 79% were within +/-1.0 D of emmetropia. At 12 months, all eyes were within +/-2.0 D. At 3 months, 85.4% of eyes had UCVA of 20/40 or better, with 95.3% achieving 20/40 or better at 6 months. At 1 year, all eyes (n = 19) had gained from 1 to 8 Snellen lines of UCVA, with most (n = 16) gaining between 3 and 7 lines. At 12 months, all eyes maintained preoperative BCVA or gained 1 to 4 lines. There was some early, transient haze < or = grade 1.5. There were no corneal infiltrates, decentered ablations, or infections. CONCLUSIONS: These data suggest that the 9 mm/5 mm hyperopic ablation profile of the VISX STAR can produce accurate corrections without significant, progressive regression. Refractive stability was achieved 3 months after surgery. We did not observe any differences in outcomes between eyes treated for primary hyperopia and eyes treated for prior myopic overcorrections. We believe the quicker ablation time (10 Hz pulse rate) helped patients maintain fixation and reduced the risk of decentration. There was a high degree of satisfaction among all patients, especially those with presbyopia.     

Wavefront-guided laser in situ keratomileusis using the WaveScan system for correction of low to moderate myopia with astigmatism: 6-month results in 277 eyes

PURPOSE: To assess the safety and effectiveness of wavefront guided LASIK surgery using the Visx WaveScan system for correction of low to moderate myopia with astigmatism. SETTING: Multicenter study at 6 sites in the United States. METHODS: In this prospective nonrandomized clinical trial, treatments were performed at 6 sites in the United States using the WaveScan (CustomVue) guided excimer laser. A total of 351 eyes were enrolled, and 277 eyes were analyzed at 6 months. RESULTS: At 6 months, 94% of eyes achieved an uncorrected visual acuity (UCVA) of 20/20 or better and 74% achieved a UCVA of 20/16 or better. Sixty-nine percent of eyes had the same or better postoperative UCVA than their preoperative best spectacle-corrected visual acuity (BSCVA). Ninety percent of eyes were within +/-0.5 diopter of intended correction. No eye lost more than 1 line of BSCVA. Total higher-order root-mean square (RMS), coma, and spherical aberration values were stable (P<.05). CONCLUSION: The data support the safety and effectiveness of the WaveScan-guided customized laser ablation using the Visx Star S4 system for correction of low to moderate myopia with astigmatism.     

飞秒激光角膜基质透镜切除术治疗中高度近视散光的临床研究

目的：飞秒激光角膜基质透镜切除( femtosecond lenticule extraction,FLEx )术治疗中高度近视散光并与标准的LASIK术比较,探讨FLEx术的安全性、有效性、可预测性。方法：随机选取行角膜屈光手术的中高度近视散光(近视度数-3.00~-10.00D,散光度≤-6.00D)患者86例172眼,分为两组进行研究,86眼使用FLEx术( A组),86眼使用标准准分子激光原位角膜磨镶术( laser in situ keratomileusis,LASIK)(B组),随访6mo,记录术后裸眼视力、最佳矫正视力、客观验光值、裂隙灯检查、术后有无并发症、角膜瓣厚度、眼压、角膜地形图。
　　结果：术后6mo,两组最佳矫正视力提高一行以上的所占比例差异有统计学意义(P<0.05),A组高于B组;两组残余屈光度数在±0.50D内所占比例(A组83.7%,B组53.4%)有统计学差异(P<0.05);裸眼视力在1.0及1.0以上的A组占100%,B组占90.7%,差异有统计学意义(P<0.05)。结论：FLEx术比传统的LASIK手术具有更好的安全性、可预测性和有效性。     

Laser in situ keratomileusis with a scanning excimer laser for the correction of low to moderate myopia with and without astigmatism

PURPOSE: To evaluate the safety and effectiveness of and patient satisfaction with laser in situ keratomileusis (LASIK) performed with a scanning excimer laser by experienced surgeons to correct low and moderate levels of myopia and astigmatism. SETTING: Clinique Laservue, Montreal, Quebec, Canada. METHODS: A consecutive series of 125 patients (236 eyes) with myopia of -0.5 to -7.0 diopters (D) and cylinder less than 2.5 D were enrolled in this single-center prospective clinical trial. The patients were treated with LASIK and followed for 6 months. The System-ALK Automated Corneal Shaper microkeratome (Bausch & Lomb Surgical) with a 180 microm thickness plate and the Technolas 217 excimer laser (Bausch & Lomb Surgical) with PlanoScan software for the stromal ablation were used in all procedures. Since this version of PlanoScan tended to undercorrect, a mean of 14.7% was added to the standard nomogram. Patient satisfaction was assessed by questionnaires administered preoperatively and 1 and 6 months postoperatively. Retreatments for enhancement were not performed during the 6-month follow-up. RESULTS: Six months after LASIK (86.4% follow-up), the mean postoperative manifest spherical equivalent was +0.02 D +/- 0.64 (SD) compared with a preoperative mean of -4.01 +/- 1.59 D. The uncorrected visual acuity was 20/40 or better in 94.6% of eyes and 20/20 or better in 81.9%. A total of 91.2% were within +/-1.0 D of emmetropia and 73.0% were within +/-0.5 D. Only 2 eyes were overcorrected by >1.0 D. Of the eyes with astigmatic myopia, 86.8% were within +/-1.0 D of the intended cylinder correction (by vector analysis) and 73.0% were within +/-0.5 D. The refractions were generally stable after 1 month, and the change in refraction between postoperative examinations was within +/-0.5 D in 88.0% of eyes. A 1-line decrease in best spectacle-corrected visual acuity was seen in 11.3% of eyes, and no eye lost more than 1 line. An increase of 1 or 2 lines was seen in 45.1%. No intraoperative problems occurred, and the interface was clear in all eyes. At 6 months, most symptoms present significantly more frequently than preoperatively were "mild"; none were "marked" or "severe." A total of 90.5% of eyes were reported with marked to extreme improvement in the overall quality of vision, and 99.0% of patients said they would choose LASIK surgery again. CONCLUSIONS: Mild to moderate myopia, with and without astigmatism, was corrected safely, effectively, and predictably with a high degree of patient satisfaction using LASIK with a scanning excimer laser and the System-ALK Automated Corneal Shaper.     

Excimer laser surface ablation: a review of recent literature

The aim was to review the recently published literature on excimer laser surface ablation procedures, including photorefractive keratectomy (PRK), laser sub‐epithelial keratomileusis (LASEK), microkeratome‐assisted PRK (epi‐LASIK) and trans‐epithelial (laser‐assisted) PRK, to help elucidate where and how surface ablation may best fit into current refractive surgical practice. The emphasis was on publications within the last three years and included systemic reviews, meta‐analyses and randomised controlled trials. Where such evidence did not exist, selective large series cohort studies, case‐controlled studies and case series with follow‐up preferably greater than six months were examined and included. Refractive and visual outcomes are excellent and comparable to those after LASIK even in complex cases after previous corneal surgery. Indeed, surface ablation combined with corneal collagen cross‐linking may be used in selected eyes with biomechanical instability, where LASIK is contraindicated. In addition, there is evidence to suggest that there may be less induction of higher order aberrations with surface techniques. Long‐term stability and safety appear to be extremely satisfactory. The literature supports the use of modern excimer laser surface treatments, with outcomes comparable to those after LASIK and evidence of less induction of higher‐order aberrations. Follow‐up studies at 10 to 20 years indicate excellent stability and safety.     

Excimer laser ablation of a corneal protuberance.

The ablation of a post-traumatic superficial corneal nodule with an argon fluoride excimer laser is reported. Three months postoperatively the area had a smooth surface with no distortion of adjacent cornea.     

Sequential ablation approach to the correction of mixed astigmatism

PURPOSE: To evaluate the safety, efficacy, and stability of LASIK, using positive cylinder and negative sphere nomograms in sequence (sequential ablation) to correct mixed astigmatism. METHODS: This prospective study included 40 eyes of 20 patients with mixed astigmatism. Patients underwent bilateral sequential ablation LASIK using the Technolas 217 excimer laser (Bausch & Lomb Surgical, Rochester, NY). The main outcome measures, uncorrected visual acuity (UCVA) and best spectacle-corrected visual acuity (BSCVA), were evaluated 3 and 12 months after surgery. RESULTS: Preoperative astigmatism ranged from +1.75 to +6.00 diopters (D) and negative sphere from -0.50 to -3.00 D. The postoperative refraction at 3 months remained unchanged at 1 year postoperative in all patients. A total of 32 (80%) eyes showed no significant residual astigmatism (<0.50 D); the remaining 8 (20%) eyes had 0.50 to 1.00 D of residual astigmatism. Residual negative sphere was present in 2 eyes of 2 patients with a planned monovision target. In the remaining 38 (95%) eyes, no significant residual negative sphere was present. Sixteen (40%) eyes had one line of improvement in BSCVA. No eye lost lines of visual acuity. The efficacy index shows that uncorrected vision after surgery is equal or better than corrected vision before surgery. Less corneal tissue is removed and fewer laser spots are required compared to other techniques for the correction of mixed astigmatism. CONCLUSIONS: The sequential ablation approach to the correction of mixed astigmatism was efficacious, safe, and stable 1 year after surgery.