Inadvertent inversion of corneal flap following microkeratome-assisted laser-assisted in situ keratomileusis

A 28-year-old male underwent microkeratome assisted Laser-assisted in situ keratomileusis (LASIK) for, myopia. On postoperative day 1, patient had a large epithelial defect in OD. The corneal epithelial defect healed within 72 hours, but sub-optimal vision persisted. The patient was referred for further management to us. On evaluation, patient had non-healing of flap margin at 5 o''clock. Fluoroscein stain revealed no corneal epithelial defect, but a large pool of dye beneath the LASIK flap. A clinical diagnosis of non-adherence of LASIK flap was considered. Application of bandage contact lens was done. LASIK flap completely healed in 1 week. Possible etiologies are discussed and literature is reviewed.     

Complications of laser-assisted in situ keratomileusis

Laser-assisted in situ keratomileusis (LASIK) is one of the most commonly performed kerato-refractive surgery globally. Since its introduction in 1990, there has been a constant evolution in its technology to improve the visual outcome. The safety, efficacy, and predictability of LASIK are well known, but complications with this procedure, although rare, are not unknown. Literature review suggests that intraoperative complications include suction loss, free cap, flap tear, buttonhole flap, decentered ablation, central island, interface debris, femtosecond laser-related complications, and others. The postoperative complications include flap striae, flap dislocation, residual refractive error, diffuse lamellar keratitis, microbial keratitis, epithelial ingrowth, refractive regression, corneal ectasia, and others. This review aims to provide a comprehensive knowledge of risk factors, clinical features, and management protocol of all the reported complications of LASIK. This knowledge will help in prevention as well as early identification and timely intervention with the appropriate strategy for achieving optimal visual outcome even in the face of complications.     

Q值引导的个体化准分子激光原位角膜磨镶术后角膜地形图分析

目的 分析Q值引导的个体化准分子激光原位角膜磨镶术后角膜地形图的动态变化.方法 将94例188只眼接受准分子激光原位角膜磨镶术治疗的近视患者分为两组,47例94只眼行非球面个体化切削作为Ⅰ组;另47例94只眼行标准切削作为Ⅱ组,采用Orbscan Ⅱ角膜地形图仪随访6个月.结果 术后各时间点切削区形态、平均偏中心距离和SimK的变化,两组比较差异无统计学意义(P>0.05),各时间点Q值差异两组比较有统计学意义(P<0.05),非球面切削组的Q值明显低于标准切削组,两组术后平均角膜厚度和切削深度的差异有统计学意义(P<0.05).结论 Q值引导的个体化准分子激光原位角膜磨镶术治疗近视具有较高的有效性、安全性和稳定性,且比标准切削更有助于维持角膜的非球面性.角膜地形图为分析评估手术效果提供了客观依据.     

非甾体抗炎药对于LASIK术后干眼的疗效分析

目的：探讨LASIK术后加用非甾体抗炎药对缓解术后干眼症的疗效。 方法：选择2010-10/11在青岛眼科医院行LASIK手术的近视66例132眼。并在术后常规用药基础上,左眼只使用人工泪液,右眼加用1g/L普拉洛芬滴眼液,进行自身对照研究。根据右眼滴用非甾体抗炎药频率不同,分为A组：4次/d（74眼）、B组：6次/d（58眼）。分别于术前、术后10d;1mo进行主观问卷调查、基础泪液分泌试验(SⅠt)、泪膜破裂时间(BUT)、角膜荧光素钠染色(FL)、虎红染色、角膜表面不规则指数(ISV)、角膜表面非对称性指数(IVA)。并对几组结果分别进行统计学分析。 结果：与对照眼比较,除ISV和IVA之外,A,B两组组内比较术后10d及1mo其余指标差异均有统计学意义。A,B两组组间比较,术后10d BUT和虎红染色的差异有统计学意义(P<0.05)。术后1mo各项指标差异无统计学意义。 结论：角膜地形图ISV和IVA对于LASIK术后干眼的诊断具有意义,但对于术后干眼治疗的疗效评价缺乏特异性;在LASIK术后加用非甾体抗炎药,能通过减轻术后炎症反应、延长泪膜破裂时间而有效的缓解术后早期的干眼症状;增加非甾体抗炎药的滴用频率并不能明显增加药效。     

Recalcitrant Pseudomonas keratitis after epipolis laser-assisted in situ keratomileusis: case report and review of the literature

We report a case of recalcitrant microbial keratitis after epipolis laser-assisted in situ keratomileusis (epi-LASIK) surgery caused by Pseudomonas aeruginosa and review the literature on resistant Pseudomonas keratitis after excimer laser surgery. Microbial keratitis occurred two weeks after epi-LASIK surgery and was resistant to fluoroquinolones, aminoglycosides and macrolides but sensitive to meropenem. The patient had total corneal melting and required therapeutic penetrating keratoplasty. The globe could be salvaged and the distance visual acuity was 6/60 in the right eye. Recalcitrant Pseudomonas keratitis might require a therapeutic graft and necessitate the use of intravenous meropenem to prevent recurrence of infection.     

LASIK手术并发症对眼波阵面像差的影响

目的　探讨屈光手术后中央岛、偏中心、不规则散光、多中心切削等并发症对眼波阵面像差的影响。方法　进行一项回顾性的临床研究 ,对接受 L ASIK手术术后发生各种并发症的 2 5例患者 (2 9只眼 )的眼波阵面像差进行了评估。采用主观性波阵面像差仪对眼波阵面像差进行了测量与比较。检查结果通过 Madlab软件分析 ,直接获取 35项 Zemike系数及每阶 Zemike系数的 RMS值。结果　无并发症组患者术前最佳矫正视力 (BCVA)是 1.0 1± 0 .12 ,术后 3月 BCVA为 0 .99± 0 .14 ;并发症组患者术前 BCVA是 1.0 2± 0 .0 9,术后 BCVA为 0 .6 1± 0 .2 4。术前眼波阵面像差的 RMS值为 0 .6 5μm ,术后无并发症组为 1.5 1μm;而中央岛组的 RMS值为 6 .78μm ;偏中心组为 7.94μm;不规则散光组为 9.32μm ;多中心切削组为 7.2 9μm。结论　 L ASIK术中术后所致的并发症可导致眼波阵面像差数倍的增加 ,严重影响患者术后的视觉质量     

Nearwork-induced transient myopia and accommodation function before and after laser-assisted in situ keratomileusis surgery

Purpose:To assess the change in Near Induced Transient Myopia (NITM) and other accommodation parameters, before and after undergoing LASIK surgery for myopia correction.Methods:Twenty-nine myopic subjects were recruited from a tertiary eye hospital in India. Age range was 21 to 35 years with an average age of 26.1 ± 3.5 years. Mean spherical equivalent was –3.86 D ± 1.50 D presurgery. NITM, lag of accommodation, near point of convergence (NPC), accommodative amplitude (AA), and binocular near accommodative facility (AF) were measured. All data were collected 21 days prior to and 30 days after LASIK surgery.Results:NITM, lag of accommodation and amplitude of accommodation were significantly lower (NITM -0.05 ± 0.15, Lag 0.38 ± 0.38, AA 10.27 ± 2.24) after surgery when compared to before (NITM 0.26 ± 0.12, Lag 0.77 ± 0.51, AA 12.18 ± 2.02; P < 0.001). Accommodative facility increased and near point of convergence was significantly more distal following surgery (AF 10.70 ± 2.29, NPC 7.96 ± 1.63) when compared to prior (AF 8.65 ± 2.74, NPC 5.62 ± 1.71; P < 0.001).Conclusion:Significant changes in NITM and accommodation function should be expected in the short term following LASIK surgery. This study supports the importance of evaluating accommodative parameters and patient counselling prior to and following refractive surgery.     

Infections following laser in situ keratomileusis: an integration of the published literature

Infections occurring after laser in situ keratomileusis (LASIK) surgery are uncommon, but the number of reports have steadily increased in recent years. This systematic, comprehensive review and analysis of the published literature has been performed in order to develop an integrative perspective on these infections. We have stratified the data by potential associations, microbiology, treatment, and the degree of visual loss, using Fisher's exact tests and Student's t-tests for analysis. In this review, we found that Gram-positive bacteria and mycobacterium were the most common causative organisms. Type of postoperative antibiotic and steroid use was not associated with particular infecting organisms or severity of visual loss. Gram-positive infections were more likely to present less than 7 days after LASIK, and they were associated with pain, discharge, epithelial defects, and anterior chamber reactions. Fungal infections were associated with redness and tearing on presentation. Mycobacterial infections were more likely to present 10 or more days after LASIK surgery. Moderate or severe visual reductions in visual acuity occurred in 49.4% of eyes. Severe reductions in visual acuity were significantly more associated with fungal infections. Flap lift and repositioning preformed within 3 days of symptom onset may be associated with better visual outcome.     

LASIK术前高度近视眼底病变临床分析及处理

目的探讨准分子激光原位角膜磨镶术（LASIK）术前高度近视眼底病变病情及治疗方法。方法对264例（496只眼）LASIK术前高度近视患者行散瞳眼底检查并作详细眼底检查记录。结果 496只眼中11只眼有干性视网膜裂孔（占2.2%）,9只眼有玻璃体牵引,4只眼伴视网膜脱离,14只眼有严重视网膜变性。11只眼干性视网膜裂孔和2只眼视网膜浅脱离行氩激光光凝治疗,2只眼视网膜脱离行巩膜外硅压术。结论高度近视眼LASIK术前常规散瞳检查眼底对发现病变并及时治疗是非常必要的。     

Analysis of the visual and refractive outcome following laser in situ keratomileusis (LASIK) retreatment over a four-year follow-up period

Purpose To evaluate the safety and refractive stability following LASIK retreatment over a four-year follow-up period. Methods In this retrospective study, 60 eyes of 52 patients underwent LASIK retreatment for residual refractive errors after LASIK. Retreatment was performed by lifting the original flap followed by laser ablation of the stromal bed. The main outcome measures at the latest follow-up visit were efficacy, predictability, safety and stability. The mean follow-up time after retreatment was 22.3 ± 10.5 (range 12–48 months). Results The baseline mean spherical equivalent (SE) was −4.85 ± 2.57 dioptres (D) (range +2.25 to −11.75 D). At the latest follow-up visit, the uncorrected visual acuity (UCVA) was 6/9 or better in 88% of the eyes, the mean SE was −0.33 ± 0.8 D (−2.50 to +2.25 D), and 77% of the eyes were within ±0.50 D of target refraction. None of the patients lost lines of best corrected visual acuity (BCVA) and 25 eyes (41%) gained one or more lines. Three eyes (5%) developed peripheral epithelial in-growth and none of the patients had corneal ectasias or retinal complications. Conclusion LASIK retreatment is a safe and effective procedure for correcting residual refractive errors after LASIK. After retreatment, the visual and refractive outcome remained stable during the four-year follow-up period of the study.     

Laser in situ keratomileusis for treated myopic anisometropic amblyopia in children

Purpose

To evaluate the effects of laser in situ keratomileusis (LASIK) in decreasing myopic anisometropia in children with spectacles or contact lens intolerance and its validity in facilitating treatment of resultant myopic anisometropic amblyopia.

Patients and methods

LASIK was performed in 18 eyes of 18 children having myopic anisometropic amblyopia not successfully treated with the standard amblyopia treatment for 6 months. Children were followed up at 1 week, 1, 2, 6, 12, 18 and 24 months. Postoperative amblyopia therapy was continued with occlusion of the dominant eye for 6 h daily for the first 3 months and then for 4 h per day as long as possible.

Results

The mean spherical equivalent refraction in the operated eye had reduced significantly from −9.08 ± 1.86D preoperatively to −0.97 ± 1.16D at 2 years postoperatively. The mean spherical equivalent in the non-operated fellow eye was −1.0 ± 1.15D preoperatively and −2.50 ± 1.15D at 2 years. The mean spherical equivalent myopic anisometropia was −7.75 ± 2.25D preoperatively and −0.50 ± 0.31D at 2 years, representing a 93.5% reduction in myopic anisometropia. The mean regression value was −2.28 ± 1.62D, however, 18 eyes (72%) were within 3.0D of the fellow eye. The mean BCVA was significantly improved from 0.72 ± 0.13 preoperatively to 0.47 ± 0.17 by 2 years after LASIK with amblyopia treatment.

Conclusion

LASIK is a safe and effective alternative method for correcting myopic anisometropic amblyopia, especially in children with spectacles or contact lens intolerance, with more better visual acuity and binocular vision.     

Diplopia as a complication of laser in situ keratomileusis surgery

A case is presented of a patient with high myopia who developed vertical binocular diplopia after decentred laser in situ keratomileusis (LASIK) surgery with associated decompensation of pre‐existing exophoria into an exotropia. A 40‐year‐old man underwent LASIK surgery for high myopia in his right eye. Preoperatively, he was approximately –26.00/–2.00 × 35° with visual acuity of 6/12^–2 in that eye. He also had an asymptomatic exophoria. After LASIK surgery, he achieved a refraction of –3.25/–0.50 × 80° with 6/21 best‐corrected visual acuity. He also developed binocular diplopia. The ablation zone had been decentred upwards and there was also an exo‐ and hypo‐deviation of his right eye. He was able to superimpose the two images in free space with vertical and horizontal prisms. A hard contact lens also resulted in superimposition of the two images. Vertical decentration of the ablation zone can induce a vertical prism effect after LASIK surgery and result in vertical diplopia. This together with abnormal optics also caused loss of best‐corrected vision and decompensation of his pre‐existing exophoria into an exotropia.     

角膜地形图引导的准分子激光治疗LASIK术后不规则散光

目的：评价角膜地形图引导的准分子激光个性化切削治疗准分子激光原位角膜磨镶术（ LASIK）术后不规则散光的临床疗效。方法选取2013年2月至2015年8月在我院就诊的患者9例（10只眼）,均为LASIK术后存在一定程度的偏中心或不规则散光。在角膜地形图引导下行准分子激光切削,比较手术前后视力、散光度、角膜不规则指数（ CIM）及高阶像差均方根（ High RMS）。结果患者术后裸眼视力由平均0.50±0.13变为术后3个月平均0.98±0.11,差异具有统计学意义（ P ＝0.00）。手术前散光绝度值1．00 D～2．50 D,平均为（1．78±0.39）D,术后3个月平均（0.62±0.22）D,手术前后差异具有统计学意义。术后CIM及High RMS均较术前下降,差异均具有统计学意义（ P ＝0.00）。结论 CRS-MASTER平台角膜地形图引导的准分子激光治疗LASIK术后不规则散光安全、有效。     

Study of change in contrast sensitivity in relation to depth of ablation after wavefront optimized myopic laser-assisted in situ keratomileusis

Purpose:The aim of this work was to study the change in contrast sensitivity (CS) in relation to depth of stromal ablation after wavefront-optimized (WFO) myopic laser in situ keratomileusis (LASIK).Methods:This was as prospective, longitudinal, comparative study. The study participants were divided into two groups: Group 1 ≤50 μ ablation depth; 60 eyes and group 2 >50 μ ablation depth; 60 eyes. All underwent WFO LASIK. Uncorrected and corrected distance visual acuity (UDVA and CDVA) and CS were measured preoperatively and postoperatively at 1 week, 2 weeks, and 2 and 6 months. Two-way repeated-measures analysis of variance (ANOVA), Unpaired t test and one-way repeated measures ANOVA were used to test differences across time periods within each treatment group. A value of P < 0.05 was considered as statistically significant.Results:The mean ablation depths in groups 1 and 2 were 39.30 μ ± 7.22 μ and 69.90 μ ± 12.09 μ, respectively; the maximum depth was 94.62 μ. In group 1, the preoperative mean CS was 1.91 ± 0.07, which improved postoperatively at 1 week (1.93 ± 0.06) and remained stable in subsequent follow-ups (1.94 ± 0.05). In group 2, the mean CS preoperatively was 1.87 ± 0.12, which postoperatively at 1 week and 6 months were 1.93 ± 0.07 and 1.94 ± 0.03, respectively (P < 0.05). Between the groups, preoperative CS was significantly different (P = 0.04), but the change in CS post-LASIK was insignificant (P > 0.05).Conclusion:There was a significant improvement in CS after WFO myopic LASIK in all patients irrespective of ablation depth (up to 94.62 μ).     

Prospective contralateral eye study to compare conventional and wavefront‐guided laser in situ keratomileusis

Purpose: To compare outcomes of customized/wavefront guided with conventional ablation in myopic patients with or without astigmatism undergoing laser in situ keratomileusis. Methods: A prospective, comparative, contralateral eye study was performed. Sixty‐eight eyes of 34 myopic patients with similar refractive error in both eyes were included. One eye was randomly selected to undergo conventional and the fellow eye customized ablation. Surgery was performed using the Technolas 217z laser (Bausch & Lomb, Surrey, UK). Uncorrected visual acuity, manifest refractive spherical equivalent (MRSE), astigmatism, aberrometry and contrast sensitivity were recorded pre and 3 months postoperatively. Results: Mean MRSE treated in the conventional and customized groups were 3.77 ± 1.61 dioptres and ?3.83 ± 1.59 dioptres respectively. Three months postoperatively there was no significant difference between the groups in mean MRSE (p = 0.99) or cylinder (p = 0.56). The factor increase in postoperative total higher order aberrations (HOAs) was less in the customized (1.32) compared with the conventional (1.54) treatment group but did not reach statistical significance (p = 0.08). Scotopic contrast sensitivity decreased significantly postoperatively in the conventional but not in the customized treatment group. Conclusion: Visual acuity and refractive error outcomes were similar in both treatment group and no patient preference was observed. Customized ablation was associated with a smaller but not statistically significant postoperative increase in HOAs, better preservation of scotopic contrast sensitivity, quicker treatment time and removal of less corneal tissue.     

Study on change in corneal biomechanics and effect of percent tissue altered in myopic laser-assisted in situ keratomileusis

Purpose:To evaluate corneal biomechanical changes and their correlation with the percentage of tissue altered (PTA) in myopic femtosecond (FS)-flap LASIK.Methods:Prospective longitudinal observational study of 80 eyes of FS LASIK. Demographic details, LASIK parameters, preoperative and postoperative (day 1, month 1, 3, and 6), UCVA, BCVA, refraction, corneal topography, corneal hysteresis (CH), and a corneal resistance factor (CRF) were noted. Change in CH and CRF and its correlation with PTA were analyzed. Data were analyzed in three subgroups [subgroup 1: PTA 23 to <27%; subgroup 2: 27 to <33%; subgroup 3: 33 to <40%].Results:FS LASIK for MRSE - 3.5D ± 1.6D with mean PTA of 31.6 ± 4.4% (range 23.8–39.8%), showed statistically significant decrease in CH and CRF. Mean CH decreased from a preoperative value of 10.4 ± 1.9 to 8.1 ± 1.1; mean CRF from 10.5 ± 1.6 to 7.5 ± 1.3 at 6-months postoperative period, respectively. Mean preoperative CH decreased by 25%, 24%, 23%, and 21% and mean preoperative CRF decreased by 34%, 28%, 28%, and 28% at postoperative day 1, month 1, 3, and 6 follow-ups. Mean CH and CRF showed a significant negative correlation with PTA (CH: r = - 0.33 [P = <0.0001], CRF: r = - 0.34 [P = <0.001]. Subgroup analysis noted greater decrease in CRF and CH in eyes with higher PTA (subgroup 3).Conclusion:Myopic FS LASIK causes a decrease in corneal biomechanics with a significant negative correlation with PTA indicating a greater decrease in corneal biomechanics with higher PTA.     

Validity of percentage tissue altered as a screening formula for post laser-assisted in-situ keratomileusis ectasia in Indian eyes

Purpose:To calculate a modified percentage tissue altered (mPTA) in post laser-assisted in-situ keratomileusis (LASIK) eyes and to validate its role as an independent factor to evaluate ectasia in the Indian population.Methods:A total of 333 consecutive eyes with normal preoperative corneal topography by combined placido and scheimpflug imaging-based topography system (SIRIUS) who underwent LASIK using a microkeratome between 2011 and 2014 at a tertiary level teaching hospital in south India, were retrospectively analyzed. Preoperatively patient''s refraction, flap thickness (FT), ablation depth (AD), residual stromal bed (RSB), and thinnest corneal thickness (TCT) were recorded. The formula used was mPTA = (FT + AD)/TCT. mPTA was grouped into <0.4 (low risk), 0.40 - 0.45 (moderate risk), and >0.45 (high risk). All patients were called for follow-up and underwent a topography to look for ectasia.Results:In total 60.1%, 29.1%, and 10.8% patients had mPTA of <0.4, 0.40 - 0.45 and >0.45, respectively. However, after a minimum follow-up of 2 years, none of the patients had any sign of ectasia.Conclusion:Careful selection of patients is mandatory before proceeding for LASIK. Factors like corneal thickness, RSB, degree of myopia, and AD are more important. The role of mPTA >0.4 as an independent risk factor for post LASIK ectasia is questionable in Indian eyes. Other factors or a modified formula suitable for Indian eyes needs to be investigated. A larger follow-up period is also required as ectasia has been known to develop even after 2 years.     

LASIK术后角膜地形图的变化及临床效果的分析

目的:探讨准分子激光原位角膜磨镶术治疗近视后角膜地形图的变化,并对其疗效、安全性和术后并发症等方面进行观察。方法:对60例(112眼)近视眼患者行准分子激光原位角膜磨镶术(LASIK),按屈光度将所有病例分为3组,Ⅰ组:-1.45～-6.20D(34眼),Ⅱ组:-6.45～-10.20D(53眼),Ⅲ组:-10.45～-14.00D(25眼)。检查术前和术后1wk;1,3及6mo的视力(裸眼视力和矫正视力)、屈光度、角膜地形图的改变。结果:模拟角膜计度数(simk)较术前降低,术后1wk角膜地形图平滑形占83%,其它形占17%,无中央小岛形成,切削形态随时间延长逐渐变规则。术后3mo裸眼视力≥1.0的各组分布比率是100%、96%、92%,屈光度在3mo术后基本稳定,术后并发症少。结论:LASIK手术是治疗近视的一种安全、有效且可预测性好的手术方法,角膜地形图可帮助我们详细了解角膜表面的形状,预测手术效果。