Reasons for not performing LASIK in refractive surgery candidates

PURPOSE: To analyze the reasons for which LASIK was rejected in eyes of patients who requested surgical correction of their refractive errors. METHODS: A retrospective study was performed in which data pertaining to refractive and ocular status of 338 patients who presented for refractive surgery at our LASIK facility between November 2002 and December 2003 were reviewed. The reasons for not performing LASIK in cases that were rejected were also noted. RESULTS: Among the 338 patients who requested refractive surgery, 223 (66%) underwent LASIK; surgery was not performed in 115 (34%) patients. The most common reason for rejecting LASIK was suboptimal central corneal thickness (55.1%). High myopia > -12.00 diopters (18.4%), keratoconus (9.6%), and hyperopia (5.9%) were other significant reasons. CONCLUSIONS: Suboptimal corneal thickness combined with a high amount of refractive error was found to be the leading cause of rejection of patients for LASIK in India.     

Dry eye after LASIK: Comparison of outcomes for Asian and Caucasian eyes

Background : Dry eye is a common complication of LASIK surgery. Our clinical impression was that post‐LASIK dry eye was more problematic for our Asian patients. The aim of this study was to determine if dry eye after LASIK is more prevalent, more sustained and more severe in Asian eyes compared with Caucasian eyes. Methods : This study was based on a retrospective analysis of a clinical database. Data (n = 932 eyes, 932 patients) was collected before and after (week 2 and months 1, 3 and 6) LASIK surgery. Patients were defined as Asian if both parents were of East Asian ethic origin. Assessments included dry eye symptoms, ocular surface staining, tear volume, tear secretion, tear film stability and corneal sensation. Results : Asian eyes had greater ocular surface staining, poorer tear film stability and lower tear volume before LASIK and at all times after LASIK. Dry eye symptoms occurring ‘often or constantly’ were more prevalent at all time points after LASIK in Asian eyes. Chronic dry eye persisting six months or more after LASIK was diagnosed in 28 per cent of Asian eyes and 5 per cent of Caucasian eyes (p < 0.001). Asian patients with chronic dry eye were predominantly female, reported dry eye symptoms, had greater ocular surface staining and lower tear secretion, stability and volume before surgery. After LASIK, Asian eyes had a slower return to pre‐operative values for ocular surface staining, tear volume and corneal sensation. Discussion : The risk of chronic dry eye after LASIK was significantly higher in Asian eyes. Contributing factors could include racial differences in eyelid and orbital anatomy, tear film parameters and blinking dynamics and higher attempted refractive corrections in Asian eyes.     

Reasons for not performing refractive surgery

PURPOSE: To analyze the reasons that laser in situ keratomileusis (LASIK) or photorefractive keratectomy (PRK) were not performed in patients who requested surgical correction of their refractive errors. SETTING: Minamiaoyama Eye Clinic, Tokyo, Japan. METHODS: This retrospective review comprised 2784 consecutive patients who visited our clinic between June 1997 and August 2000. The reasons they did not receive refractive surgery (PRK or LASIK) were analyzed. RESULTS: Among the 2784 patients who requested surgery for refractive errors, 2079 patients (74.7%) had PRK or LASIK and 705 patients (25.3%) did not. The most common reasons for not treating patients surgically were myopia greater than -12.0 diopters and/or high astigmatism (20.7%), insufficient corneal thickness (8.2%), keratoconus (6.4%), cataract (5.7%), and hyperopia and/or hyperopic astigmatism (4.1%). CONCLUSIONS: Patients who request surgery have a variety of problems. Attention must be given to these individual problems, and the indications must be considered.     

LASIK手术常见临床禁忌证分析

目的:探讨常见LASIK手术禁忌证的发生情况。方法:对拟行LASIK手术2693例(5304眼)进行详细术前检查,对未行手术的476例906眼进行原因分析。结果:476例906眼未能手术患者的原因包括角膜厚度不够(<450μm)、矫正视力<0.5、超高度近视、眼压高、圆锥角膜、视网膜变性或裂孔、瞳孔偏大、角膜瘢痕、慢性泪囊炎、瘢痕体质、思想顾虑大等。其中最常见的原因为角膜厚度不够298眼(32.89%)、矫正视力<0.5者155眼(17.11%)和思想顾虑大134眼(14.79%)。结论:LASIK术前必须进行严格的检查,除外手术的禁忌证,以保证手术的安全性。     

299例未行准分子激光原位角膜磨镶术的原因分析

目的 :探讨未行准分子激光原位角膜磨镶术病例的原因。方法 :对 15 99例中经检查后未行LASIK手术的 2 99例 (占 18.6 % )患者的原因进行了分析。结果 :2 99例中 15 3例对手术有顾虑 (占 5 1.2 % ) ;角膜厚度不足有 4 4例 (占 14 .7% ) ;角膜屈光力偏大 34例 (占 11.0 % ) ;矫正视力不良 2 9例 (占 9.7% ) ;高眼压 18例 (占 6 .0 % ) ,眼底病变 11例 (占 3.7% ) ;其他原因 10例 (占 3.3% )。结论 :LASIK手术有明显的选择性 ,患者术前存在着明显的心理因素     

Contact lens fitting difficulties following refractive surgery for high myopia.

PURPOSE: To describe the clinical and optical problems encountered in contact lens fitting following refractive surgery for high myopia. METHODS: Following refractive surgery for high myopia (greater than -10.00 D) we corrected residual refractive errors with contact lenses in the four eyes of two patients. The first patient had undergone bilateral laser in situ keratomileusis (LASIK),with two subsequent LASIK retreatments in the left eye. Ten months later she was fit with rigid gas permeable (RGP) lenses in both eyes. The second patient had undergone a clear lens extraction in the right eye and radial keratotomy followed by photorefractive keratectomy(PRK) in the left eye. She was fit with toric soft lenses six years postoperatively. RESULTS: Final visual acuity obtained with contact lenses was 20/25-20/20 in all eyes. The first patient required significant minus lens power compensation. Furthermore, the RGP lens in the left eye was slightly decentered due to corneal irregularity induced by LASIK. The second patient had regular corneal surfaces and was successfully fit with daily wear toric soft lenses despite the 2.75 D of residual astigmatism in the left eye. CONCLUSIONS: Following refractive surgery for high myopia a proportion of patients will remain undercorrected. In these patients the alterations in corneal architecture that ensue make contact lens fitting more challenging. Patients with regular astigmatism may be fitted successfully with toric soft lenses. Patients with corneal irregularities should be fit with RGP lenses.     

Two cases of a penetrating keratoplasty with tissue from a donor who had undergone LASIK surgery.

PURPOSE: To report two cases of penetrating keratoplasty using tissue from a donor who had undergone laser-assisted in situ keratomileusis (LASIK) surgery before its transplantation. PARTICIPANTS: Two patients who had penetrating keratoplasties and received donor corneas from eyes that had previous LASIK. INTERVENTION: The two patients underwent corneal transplantation by two different surgeons who were unaware that the donor eyes had previous LASIK treatment. RESULTS: Penetrating keratoplasty was completed without complication in both cases, although a separation of the corneal lamellae was noted during surgery in one of the cases. The two patients are doing well at 5.5 months postsurgery. CONCLUSION: With the increasing popularity of laser refractive surgery, eye banks should increase their awareness and refine screening techniques to rule out refractive surgery in the donor corneas. The long-term follow-up of those patients will reveal if surgical success was compromised by prior refractive surgery.     

Refractive changes caused by hypoxia after laser in situ keratomileusis surgery

OBJECTIVE: To determine whether hypoxia induces refractive changes in subjects who have had laser in situ keratomileusis (LASIK) refractive surgery. DESIGN: Prospective paired eye clinical trial. PARTICIPANTS: There were 20 LASIK subjects (40 eyes) and 20 myopic non-LASIK controls (40 eyes). INTERVENTION: Each subject had one eye exposed to ocular surface hypoxia (humidified nitrogen) by use of an airtight goggle system at sea level for 2 hours. The other eye was simultaneously exposed to humidified, compressed air (21% oxygen) with the same airtight goggle system. MAIN OUTCOME MEASURES: Keratometry, cycloplegic refraction, and pachymetry were compared before and after exposure by use of repeated measures analysis of variance. RESULTS: A significant myopic shift (P: < 0.01) occurred in LASIK corneas exposed to hypoxia compared with myopic control subjects. A significant increase in corneal thickening occurred symmetrically in both LASIK and control subjects exposed to hypoxia. There was a trend toward corneal steepening (keratometry) in LASIK subjects, but this was not statistically significant. CONCLUSIONS: These results suggest that ocular surface hypoxia induces a myopic shift in LASIK subjects.     

Chronic dry eye and regression after laser in situ keratomileusis for myopia

PURPOSE: To examine the relationship between chronic dry eye and refractive regression after laser in situ keratomileusis (LASIK) for myopia. SETTING: Excimer Laser Vision Centre and Centre for Eye Research, Queensland University of Technology, Brisbane, Australia. METHODS: This study was based on a retrospective analysis of a clinical database and a case study series. Data (N = 565 eyes) were collected before and after (2 weeks and 1, 3, 6, and 12 months) LASIK. Three case studies, which highlight appropriate management strategies for LASIK candidates with dry eye, are presented. RESULTS: Regression after LASIK was related to chronic dry eye. It occurred in 12 (27%) of 45 patients with chronic dry eye and in 34 (7%) of 520 patients without (P<.0001). Patients with chronic dry eye had significantly worse myopic outcomes than those without (1 month, P =.02; 3 months, P =.01; 6 months, P =.004; 12 months, P =.008). The risk for chronic dry eye was significantly associated with female sex, higher attempted refractive correction, greater ablation depth, and the following pre-LASIK variables: increased ocular surface staining; lower tear volume, tear stability, and corneal sensation; and dry-eye symptoms before LASIK. The risk for regression was significantly associated with higher attempted refractive correction, greater ablation depth, and dry-eye symptoms after LASIK. Case studies demonstrated that intensive dry-eye treatment may improve the refractive outcome and alleviate the need for enhancement surgery. CONCLUSION: The risk for refractive regression after LASIK was increased in patients with chronic dry eye.     

近视未行LASIK手术824例分析

目的:探讨近视行术前检查而未行准分子激光原位角膜磨镶术(laser in situkeratomileusis,LASIK)原因。方法:对2891例近视患者常规进行术前检查,未行手术824例进行原因分析。结果:未行LASIK手术824例中,角膜厚度不足297例(36.0%);存在思想顾虑194例(23.5%);瞳孔过大96例(11.6%);角膜前后表面高度(眼前节全景仪Pentacam基于Scheimpflug成像原理,获得全角膜前、后表面角膜地形图及各点角膜厚度,可应用于圆锥角膜筛查和早期诊断)偏高50例(6.1%),高曲率46例(5.6%),矫正视力不佳43例(5.2%),眼底病变31例(3.8%),干眼31例(3.8%),其它36例(4.4%)。结论:LASIK手术是一种选择性手术,必须进行严格的术前筛查,全面科学评估检查结果,医患之间加强沟通,严格掌握手术的适应证和禁忌证。     

Refractive change in response to acute hyperbaric stress in refractive surgery patients

PURPOSE: To determine whether acute hyperbaric stress affects visual acuity or refractive power after keratorefractive surgery. SETTING: Clinical multiplace hyperbaric chamber and ophthalmology clinic, University of California, San Diego, California, USA. METHODS: This prospective convenience sample study included 3 groups: 3 patients who had had bilateral myopic radial keratotomy (RK); 2 who had had bilateral myopic laser in situ keratomileusis (LASIK); and 4 control subjects who had no previous corneal refractive surgery or ocular pathology but had a myopic refractive error (-1.25 to -8.38 diopters [D]) similar to that in the treated patients before refractive surgery. One additional patient had had unilateral LASIK only and was included in the LASIK and control groups. Best spectacle-corrected visual acuity (BSCVA), manifest spherocylindrical refractive error, and intraocular pressure were measured at baseline, at 4 atmospheres absolute (atm abs), and on return to ambient pressure. Corneal pachymetry and keratometry were measured at baseline and on return to ambient pressure. RESULTS: The mean BSCVA changed from 0.06 logMAR (20/25 Snellen equivalent) at baseline to 0.10 logMAR (20/25) at 4 atm abs in the RK group and from 0.00 logMAR (20/20) to -0.06 logMAR (20/15) in the LASIK group; it did not change in the control group. The mean refractive error changed from 0.25 D at baseline to 0.50 D at 4 atm abs in the RK group, from -0.90 to -1.02 D in the LASIK group, and from -4.58 to -4.53 D in the control group. CONCLUSIONS: Acute hyperbaric stress did not appear to alter refractive power after corneal surgery.     

未行LASIK手术239例原因分析

目的:探讨经常规准分子激光原位角膜磨镶术(laserin situ keratomileusis,LASIK)术前检查后未行手术的原因。方法:对行LASIK术前检查的884例屈光不正患者中未行手术的239例患者进行原因分析。结果:未行LASIK手术的239例中,角膜厚度不足76例(31.8%);高眼压33例(13.8%);高角膜曲率27例(11.3%);Diff值(Orbscan-Ⅱ角膜地形图仪测得,为角膜后表面高度图的最高点超出参照面高度,是诊断早期圆锥角膜的客观依据之一)偏高21例(8.8%);视网膜出血、囊变、裂孔17例(7.1%);角膜炎16例(6.7%);干眼9例(3.8%);矫正视力不佳7例(2.9%);瞳孔过大3例(1.3%);全身病3例(1.3%);心理精神因素9例(3.8%);其他18例(7.5%)。结论:LASIK手术是一种选择性手术,必须严格细致地进行术前检查,对患者进行全面的术前评估,掌握其适应证及禁忌证,才能保证手术的安全性,使手术取得满意的效果。     

LASIK术后角膜基质床及全角膜厚度的变化及相关因素分析

目的:通过观察LASIK手术的患者术前、术中及术后1wk;1,3,6mo角膜厚度及屈光状态的变化,探讨LASIK术后屈光度数回退的原因及影响因素。方法:选择我院进行LASIK手术的患者856例856眼,分别测量其术前角膜厚度、术中角膜瓣及基质床厚度;术后1wk;1,3,6mo角膜厚度,观察屈光状态的变化,分析实际切削深度与预计切削深度的差异,屈光回退的可能原因。结果:实际角膜切削深度较准分子激光机显示理论角膜切削深度深22.15±7.23μm。角膜中央厚度变化在术后6mo以后趋于稳定。屈光度数回退量与年龄、角膜床厚度呈负相关,与术前屈光度呈正相关。结论:LASIK手术中实际切削深度与预计切削深度稍有差异,充分考虑这点有助于提高手术的安全性。准确掌握术中的实际切削深度是提高手术安全性的保障。     

Prospective, paired comparison of laser in situ keratomileusis and laser epithelial keratomileusis for myopia less than -6.00 diopters

PURPOSE: To compare visual and refractive results, contrast sensitivity, and tear stability after laser in situ keratomileusis (LASIK) in one eye and laser epithelial keratomileusis (LASEK) in the fellow eye for low myopia. METHODS: Patients diagnosed with low myopia, with a maximum difference of 1 D between their two eyes, were randomly assigned to receive LASEK on one eye and LASIK on the other eye. A total of 64 eyes of 32 patients with a mean age of 26.83 +/- 5.33 years were included in the study. Preoperative myopia ranged from -1.00 to -6.00 D. Follow-up was 6 to 12 months. Uncorrected (UCVA) and best spectacle-corrected visual acuity (BSCVA), Schirmer test results, tear break-up time, corneal asphericity, corneal uniformity index, predicted corneal acuity, and contrast sensitivity values were compared with preoperative values. A Wilcoxon test was used for statistical comparisons and a P-value less than .05 was considered significant. RESULTS: At 6 months after surgery, there was no statistically significant difference in UCVA, BSCVA, spherical and cylindrical refractive error, Schirmer test, or tear break-up time between groups. Contrast sensitivity values in the LASIK eyes were lower in comparison to preoperative values, but there was no change in the LASEK group. CONCLUSIONS: Based on 6-month results, LASEK for low myopia was safe and effective with predictable results, offered early refractive stability, and may be considered an alternative for LASIK.     

Dry eye after LASIK for myopia: Incidence and risk factors

PURPOSE: Patients frequently experience dry eye symptoms after laser-assisted in situ keratomileusis (LASIK). The purpose of this study was to determine the incidence and risk factors of dry eye after myopic LASIK. METHODS: In this retrospective case series 190 eyes that underwent LASIK were examined for a dry eye syndrome. All patents were asymptomatic for dry eyes before surgery. Assessments included subjective complaints of dry eye, tear break-up time (TBUT), corneal staining, corneal sensitivity test, and Schirmer I test. All values were compared before and at 1 week and 1.3 and 6 months after surgery. RESULTS: For the 190 eyes, chronic dry eye persisting 6 months or more after LASIK was diagnosed in 20 percent of the eyes. Mean patient age was 31 +/- 8 years. The risk for chronic dry eye was significantly associated with higher attempted refractive correction, greater ablation depth, and female sex (p=0.001). Subjective score for dryness was increased after LASIK. The greatest change from preoperative levels for all parameters was noted at 1 week. There were obvious decreases in TBUT and Schirmer value at 1, 3, and 6 months postoperatively relative to preoperative level (p<0.05). The Schirmer I test result was higher at 1 day but without statistical significance (p>0.05), but lower at 1 week and 3 and 6 months (p<0.05) after LASIK. Corneal sensitivity was decreased at 1 month and 3 months, and returned to the preoperative level at 6 months after LASIK. There was a statistically significant effect of age, sex, and mean spherical equivalent refraction on corneal sensitivity (p<0.001). CONCLUSIONS: Patients undergoing LASIK for myopia develop dry eye with compromised tear function at least 6 months after surgery. Women and patients requiring higher refractive correction have an increased risk for developing dry eye.     

LASIK术后干眼症研究

目的:研究LASIK术后干眼症的发病率在高度近视人群和低度近视人群之间的差异性以及探讨预防的方法与机制。方法:这项研究是基于对2010-05/2011-05在武汉市爱尔眼科医院接受LASIK手术388例患者的回顾性分析。患者被区分为高度近视和低度近视,数据包括干眼症状、泪液量、泪液分泌、泪膜稳定性、角膜上皮缺损等,分析采用SPSS15.0统计学软件。结果:LASIK术后高度近视患者中干眼症症状的发病率明显高于低度近视人群,高度近视患者在LASIK手术前和手术后的各个观察时间段的泪液量较低,泪膜稳定性较差,术后患干眼症症状的比率显著高于低度近视患者。结论:无论是高度近视人群还是低度近视人群,女性患干眼症的比率明显高于男性。LASIK术后高度近视患者患干眼症的几率明显高于低度近视患者,而且高度近视患者比低度近视患者在术后患干眼症的症状更严重,更持久,治疗恢复时间也更长。预防和处置LASIK术后干眼症的发病几率要重在术前检查筛选,提前治疗干预。对于高度近视患者,要尽可能选择ICL或TICL手术来进行屈光矫正。     

Considerations of glaucoma in patients undergoing corneal refractive surgery

Glaucoma patients present a unique set of challenges to physicians performing corneal refractive surgery. Corneal thickness, which is modified during corneal refractive surgery, plays an important role in monitoring glaucoma patients because of its effect on the measured intraocular pressure. Patients undergo a transient but significant rise in intraocular pressure during the laser-assisted in situ keratomileusis (LASIK) procedure with risk of further optic nerve damage or retinal vein occlusion. Glaucoma patients with filtering blebs are also at risk of damage to the bleb by the suction ring. Steroids, typically used after refractive surgery, can increase intraocular pressure in steroid responders, which is more prevalent among glaucoma patients. Flap interface fluid after LASIK, causing an artificially low pressure reading and masking an elevated pressure has been reported. The refractive surgeon's awareness of these potential complications and challenges will better prepare them for proper management of glaucoma patients who request corneal refractive surgery.     

飞秒激光制瓣与机械板层刀制瓣的LASIK术后临床疗效的比较

目的：比较飞秒激光制瓣的LASIK(Femto-LASIK)与经典的机械板层刀制瓣的准分子激光原位角膜磨镶术两种手术方式矫治近视患者的安全性、有效性及术后视觉质量的区别。

方法：回顾性病例对照研究,选取2016-07/2017-06在襄阳市中心医院飞秒激光中心进行板层刀制瓣-LASIK(62例124眼)或Femto-LASIK(58例116眼)手术的近视患者120例240眼。测量两种不同制瓣术式中制作的角膜瓣厚度以及术后视力、屈光状态及角膜地形图参数和像差等并进行比较。

结果：所有患者角膜瓣均制作成功,并且都顺利地完成了手术,术中及术后无明显的并发症发生。术后两组间患者的裸眼视力、屈光度差异无统计学意义(P>0.05)。术中Femto-LASIK组制作的角膜瓣厚度与预设差值小于板层刀制瓣-LASIK组(t=26.67,P<0.01),且球差、彗差和总高阶像差增幅均小于板层刀制瓣-LASIK组(t=-4.16、-4.92、-22.19,均P<0.01)。板层刀制瓣-LASIK组和Femto-LASIK术后角膜表面规则指数(SRI)分别为0.31±0.09、0.25±0.04,二者比较差异有统计学意义(t=6.59,P<0.01)。

结论：飞秒激光制作角膜瓣比板层刀制瓣较为精确,并且术后角膜的像差相对较小,飞秒激光制瓣可提供相对较好的视觉质量,但是这两种制瓣方式术后患者的裸眼视力和屈光状态无明显差异。     

准分子激光原位角膜磨镶术后干眼和屈光回退的相关性(英文)

目的:探讨准分子激光原位角膜磨镶术后干眼和屈光回退的相关性。方法:近视患者225例分别在LASIK术前及术后6mo进行Schirmer试验、泪膜破裂时间、角膜知觉和角、结膜荧光素染色检查,并接受McMonnies问卷调查。综合病史及治疗效果对结果作比较分析。结果:LASIK术后干眼和屈光回退显著相关。术后发生干眼症的32例患者中8例(25.0%)同时伴有屈光回退,而未发生干眼症的193例患者中仅18例(9.3%)伴有屈光回退,差异有极显著意义(P<0.01)。结论:LASIK术后干眼患者屈光回退的危险性增加。     

接受术前检查后未行准分子激光原位角膜磨镶术原因分析

目的分析屈光不正患者已接受准分子激光原位角膜磨镶术(laser in situ keratomileusis,LASIK)术前常规检查后最终未实施手术治疗的原因。方法自2003年1月开展LASIK治疗近视至2005年9月,共检查屈光不正患者1841例,其中185例(10.05%)最终未行LASIK,分析其原因。结果未行LASIK的原因为:角膜厚度不足74例(40.00%),思想顾虑47例(25.41%),社会因素34例(18.38%),视网膜严重病变11例(5.95%),青光眼或可疑青光眼9例(4.86%),矫正视力差7例(3.78%),圆锥角膜或可疑圆锥角膜3例(1.62%)。结论对近视度数相对高、角膜厚度相对薄的病例,LASIK具有明显的局限性。正确引导LASIK,术前认真检查和宣教,严格掌握手术适应证和禁忌证是减少医疗纠纷的关键。同时,应减少社会因素对近视手术选择的影响。