Risk factors and prognosis for corneal ectasia after LASIK

PURPOSE: To review cases of corneal ectasia after laser in situ keratomileusis (LASIK), identify preoperative risk factors, and evaluate methods and success rates of visual rehabilitation for these cases. DESIGN: Retrospective nonrandomized comparative trial. PARTICIPANTS: Ten eyes from seven patients identified as developing corneal ectasia after LASIK, 33 previously reported ectasia cases, and two control groups with uneventful LASIK and normal postoperative courses: 100 consecutive cases (first control group), and 100 consecutive cases with high myopia (> 8 diopters [D]) preoperatively (second control group). METHODS: Retrospective review of preoperative and postoperative data for each case compared with that of previously reported cases and cases with uneventful postoperative courses. MAIN OUTCOME MEASURES: Preoperative refraction, topographic features, residual stromal bed thickness (RSB), time to the development of ectasia, number of enhancements, final best-corrected visual acuity (BCVA), and method of final correction. RESULTS: Length of follow-up averaged 23.4 months (range, 6-48 months) after LASIK. Mean time to the development of ectasia averaged 16.3 months (range, 1-45 months). Preoperative refraction averaged -8.69 D compared with -5.37 D for the first control group (P = 0.005). Preoperatively, 88% of ectasia cases met criteria for forme fruste keratoconus, compared with 2% of the first control group (P < 0.0000001) and 4% of the second control group (P = 0.0000001). Seven eyes (70%) had RSB <250 microm, as did 16% of eyes in the first control group and 46% of the second control group. The mean RSB for ectasia cases (222.8 microm) was significantly less than that for the first control group (293.6 micro m, P = 0.0004) and the second control group (256.5 microm; P = 0.04). Seven eyes (70%) had enhancements. Only 10% of eyes lost more than one line of BCVA, and all patients eventually achieved corrected vision of 20/30 or better. One case required penetrating keratoplasty (10%), while all others required rigid gas-permeable contact lenses for correction. CONCLUSIONS: Significant risk factors for the development of ectasia after LASIK include high myopia, forme fruste keratoconus, and low RSB. All patients had at least one risk factor other than high myopia, and significant differences remained even when controlling for myopia. Multiple enhancements were common among affected cases, but their causative role remains unknown. We did not identify any patients who developed ectasia without recognizable preoperative risk factors.     

Late onset corneal ectasia after LASIK surgery

Purpose

To report late onset corneal ectasia following myopic LASIK.

Methods

A retrospective cohort case series. Nineteen patients with late onset corneal ectasia following LASIK procedure were examined at The Eye Center, Riyadh, Saudi Arabia. Patients underwent LASIK for myopia with spherical equivalent ranging from −1.4 to −13.75 diopters. Age and gender, history of systemic or local diseases, and time of onset of corneal ectasia were recorded. Eye examination and corneal topographical analyses were done before and after LASIK surgery.

Results

Nineteen patients (29 eyes) with late onset corneal ectasia were identified from 1998 to 2008 in 13 male and six female patients. The mean follow-up period was 108 ± 23 months (range 72–144 months). No patient had pre-operative identifiable risk factors for corneal ectasia and the mean time of onset was 57 ± 24 months (range 24–120 months after LASIK). The pre-operative values included mean central pachymetry 553 ± 25 μm, mean keratometry reading of 42.9 ± 1.5 diopters, average oblique cylinder of 1.4 ± 1.2 diopters, posterior surface elevation of 26 ± 2.1 diopters, corneal flap thickness of 160 μm, mean spherical equivalent of −5.6 ± 3.6 diopters, and calculated residual corneal stromal bed thickness was 288 ± 35 μm. Three (5 eyes) patients developed ectasia after pregnancy. Three (4 eyes) patients developed corneal ectasia following severe adenoviral keratoconjunctivitis and had positive PCR for adenovirus type 8.

Conclusions

Corneal ectasia may develop many years after LASIK surgery and symptoms could go undetected for some time. Pregnancy and adenoviral keratoconjunctivitis occurred post-operatively in six patients.     

近视LASIK术后角膜膨隆的研究进展

角膜膨隆是近视LASIK术后少见而严重的并发症之一。它严重损害视功能,是对公众健康的潜在危胁。本文从近视LASIK术后角膜膨隆的一般概况、发病的危险因素、病理变化、发病机制、临床特征及诊断、处理等方面总结了近年来对其研究现状及进展。     

PTK-PRK-CXL和PTK-CXL治疗LASIK术后角膜膨隆的疗效

目的评价准分子激光治疗性角膜切削术(phototherapeutic keratectomy,PTK)联合角膜交联(corneal cross-linking,CXL)术(PTK-CXL)和准分子激光治疗性角膜切削术、准分子激光屈光性角膜切削术(photorefractive keratectomy,PRK)联合CXL术(PTK-PRK-CXL)治疗准分子激光原位角膜磨镶术(laser in situ keratomileusis,LASIK)术后角膜膨隆的临床效果。方法选取LASIK术后角膜膨隆的患者28例(40眼),根据手术方式不同分为PTK-CXL组和PTK-PRK-CXL组。分别在治疗前及治疗后6个月、12个月测量患者的视敏度、屈光度、最大角膜曲率(maximum keratometry,Kmax)、最薄点角膜厚度(thinnest corneal thickness,TCT)、角膜内皮细胞计数(endothelial cell count,ECC)。将术后不同时间点的观察结果与术前做自身对照,并比较两组不同观察指标的变化量差异。结果两组均能有效降低患者的角膜曲率和屈光度,提高...     

Posterior corneal ectasia following LASIK

PURPOSE: To evaluate the cases of posterior corneal ectasia following laser in situ keratomileusis. MATERIAL AND METHODS: Thirteen eyes of 7 patients, that were diagnosed to have posterior corneal ectasia (?0.060 mm) on Orbscan topographic system following LASIK, were identified. The parameters evaluated were uncorrected visual acuity (UCVA), best-corrected visual acuity (BCVA), refraction, contrast sensitivity, glare, corneal topography, keratometry and pachymetry. The preoperative and postoperative data at day 1, 1 week, 1 month, 3 months, 6 months and 1 year were retrospectively analyzed. RESULTS: The mean UCVA of the patients before LASIK surgery was 0.032 +/- 0.04. It was 0.320 +/- 0.159 in follow-up of LASIK surgery after 1 year. The mean Pre-LASIK BCVA was 0.59 +/- 0.11. There was no change in mean BCVA at 1 year. The mean preoperative spherical equivalent was -14.25 +/- 2.91 D except in 2 hyperopic eyes in which the mean spherical equivalent preoperatively was +5.75 +/- 0.35 D. The mean postoperative spherical equivalent after 1 year of LASIK surgery in last follow-up (+/- enhancement) was - 3.45 +/- 2.08 in the myopic eyes and + 1.0 +/- 0.70 in the two hyperopic eyes. The mean preoperative posterior corneal elevation was 0.022 +/- 0.011 mm, which at the end of 1 week following LASIK was 0.067 +/- 0.009 and at 1 year/ last follow-up following LASIK, it was 0.068 +/- 0.006 mm. CONCLUSIONS: Higher amplitudes of refractive correction may lead to the occurrence of posterior corneal ectasia.     

Corneal ectasia after hyperopic LASIK

PURPOSE: To report two cases of corneal ectasia, which developed after hyperopic LASIK. METHODS: Preoperative pellucid marginal corneal degeneration was observed in patient 1. Patient 2 had no preoperative risk factors. RESULTS: Patient 1, a 47-year-old man, developed corneal ectasia in his right eye 6 months after unilateral hyperopic LASIK. Preoperative manifest refraction was +2.00 +1.50 x 178 in the right eye and +1.00 sphere in the left eye. Corneal thickness was 585 microm and 575 microm (right and left eye, respectively). Preoperative topography of the right eye demonstrated inferior steepening in the far periphery, suggestive of early pellucid marginal corneal degeneration. Patient 2, a 35-year-old man, developed corneal ectasia in his right eye > 3 years after bilateral LASIK. Preoperative manifest refraction was +2.50 sphere and +3.25 sphere (right and left eye, respectively), and corneal thickness was 556 microm in both eyes. Preoperative topography was normal in both eyes with no evidence of asymmetry, steepening, or irregularity. CONCLUSIONS: Corneal ectasia can occur after hyperopic LASIK in patients with or without recognized preoperative risk factors. Although uncommon, patients with pellucid marginal corneal degeneration can have hyperopic refractions and are at high risk for developing corneal ectasia after LASIK.     

LASIK后角膜异物的临床观察与处理

目的 探讨ＬＡＳＩＫ后角膜异物的临床特点,寻找较好的处理方法,避免产生严重并发症。方法 对３４例ＬＡＳＩＫ后角膜异物,根据异物的大小、化学性质、嵌入角膜的深浅、所引起角膜与前房的反应情况及ＬＡＳＩＫ后时间的长短,给予不同处理。结果 所有病例均无角膜瓣移位及皱折,除外角膜瞳孔区留有瘢痕者,其余均对矫正视力无影响。结论ＬＡＳＩＫ后早期,患者对角膜异物感觉不明显,自觉症状较正常情况轻,一旦异物损伤角膜较     

Risk factors for night vision complaints after LASIK for myopia

PURPOSE: To study the preoperative risk factors for night vision complaints (NVCs) after LASIK in a clinical setting. DESIGN: Retrospective noncomparative case series. PARTICIPANTS: Seven hundred ninety-five patients (1488 eyes) who underwent LASIK for myopia up to -9.75 diopters (D) (from January 1 to December 31, 1999). SETTING: Private clinic. METHODS: A complete preoperative examination was performed. Patients had bilateral LASIK surgery using the Nidek EC-5000 non-wavefront guided slit-scanning excimer laser and the Moria LSK One microkeratome. Patients were observed postoperatively for 12 months. MAIN OUTCOME MEASURES: The reported NVCs for each eye were rated on a subjective scale based on functional visual comfort. Clinically important NVC odds ratios (ORs) were calculated. RESULTS: Reports of NVCs decreased considerably from 25.6% at 1 month to 4.7% at 12 months postoperatively, at which time all patients reported similar NVCs in both eyes. Stratification of risk factors at 12 months postoperatively showed a 2.8-times increase in NVCs for initial myopia of >5 D, a 2.5-times increase for an optical zone of 相似文献   

LASIK术后角膜后表面高度变化及影响因素

目的 研究准分子激光原位角膜磨镶术(LASIK)后角膜后表面高度的变化及影响因素.方法 回顾性系列病例研究.对51(102眼)例近视眼患者施行LASIK手术,于术前、术后1个月和3个月进行Pentacam眼前节分析系统检查.在角膜中央4 mm区域将角膜分为4个象限(颞上、颞下、鼻上和鼻下),每个象限取7个点,分别分析4个象限和角膜顶点后表面高度的变化.数据采用配对t检验和相关分析.结果 角膜中央4 mm区域,术后1个月角膜顶点、颞上、颞下、鼻上、鼻下象限角膜后表面高度变化平均为(-0.12±1.50)μm、(0.18±1.70)μm、(-0.16±1.50)μm、(0.15±1.62)μm、(0.01±1.45)μm;3个月时分别为(0.58±1.49)μm、(0.42±1.85) μm、(-0.50±1.99)μm、(0.59±1.67)μm、(-0.36±1.70)μm;术后1个月和3个月比较角膜顶点后表面高度变化有统计学意义(t=2.05,P＜0.05),其余各象限变化均没有统计学意义.角膜后表面高度变化术后1个月各部位与平均角膜中央厚度(CCT)、平均剩余角膜基质床厚度(RBT)、平均手术切削深度(AD)、等效球镜(SE)均没有相关性;3个月时角膜顶点后表面高度变化与SE成正相关(r=0.26,P＜0.01),其余各象限与CCT、RBT、AD、SE均没有相关性.结论 角膜中央直径4 mm范围内,LASIK术后各部位角膜后表面高度变化量(前凸和后移)均微小.同时随着预矫屈光度的增加角膜顶点后表面前移量逐渐增加.