重视角膜生物力学特性在提高激光角膜屈光手术远期安全性中的作用

角膜激光近视手术在我国已开展近三十年,手术的临床效果良好,手术的稳定性、远期安全性更是一直被关注的焦点。角膜组织是一种典型的黏弹性组织,作为人眼重要的屈光介质,其生物力学特性是影响角膜屈光手术可预测性及稳定性的重要因素,涉及手术方式及设计、手术安全性及稳定性等多个方面。角膜生物力学特性的异常改变与角膜屈光术后发生角膜扩张、屈光回退密切相关。因此,重视角膜生物力学特性在角膜屈光手术中的作用,对于提高角膜屈光手术的安全性、有效性及可预测性十分重要。     

角膜黏合抗张力与准分子激光角膜屈光手术

近20年来,准分子激光角膜屈光手术经历了飞速发展,手术量不断增加。然而,并发症的发生也日益凸显。角膜扩张是严重的术后并发症,它的发生影响了手术的安全性和有效性。近年,关于角膜生物力学的研究,试图找到准分子激光术后角膜扩张的原因和预防措施。角膜黏合抗张力的研究为角膜扩张的术前预防提供了全新的思路与依据。     

角膜屈光手术对角膜稳定性的影响

角膜做为眼屈光系统的重要组成部分 ,其形态、透明度、稳定性等都对维持正常的眼屈光状态起着至关重要的作用。角膜屈光手术正是通过改变角膜的弯曲度 ,从而达到矫治屈光不正的目的。近年来的角膜屈光手术发展迅速 ,精确度及安全性不断提高 ,有效地矫治了各种屈光不正。但越来越多的学者发现 ,角膜屈光手术由于改变了角膜的正常结构 ,对角膜的稳定性产生了较大的影响 ,有些甚至发生严重的并发症。本文就此方面做一简要综述。一、各种角膜屈光手术对角膜稳定性的影响1 放射状角膜切开术 (RK) :195 3年 ,Sato首次在人角膜前、后表面放射状切…     

相干光断层扫描技术在角膜屈光手术中的应用

相干光断层扫描（optical coherence tomography, OCT）是一项非接触性、非侵入性、高分辨率的生物组织结构显像技术,可提供形态学图像和量化分析。其在角膜屈光手术方面的应用除了角膜厚度的测量、角膜瓣的评估、负压对视网膜影响的评估等方面之外,在圆锥角膜的筛查、角膜病变的观察与手术设计、术前黄斑区病变的筛查和术后视力预测等方面也发挥重要的作用。重视OCT在角膜屈光手术中的综合应用,有利于提高角膜屈光手术的效果。     

个性化角膜屈光手术的研究进展

角膜屈光手术目前正广泛开展，是矫正屈光不正最常见的手术方式。传统角膜屈光手术可能会出现医源性高阶像差，且对不规则角膜的矫正的能力不足，可能导致视觉质量下降、夜间主观症状增加。个性化角膜屈光手术能考虑到角膜形态、厚度与患者需求，为患者提供更好的术后视力及视觉质量。除了作为一期屈光不正的矫正手段外，个性化手术也能为术后角膜形态不规则、高阶像差及主观症状明显的患者提供增效治疗。现就个性化角膜屈光手术的设计原理、适应证、临床应用、并发症、手术效果及患者满意度等方面进行综述。     

角膜屈光手术后角膜生物力学变化特点的研究进展

角膜生物力学是对角膜黏性阻力、整体硬度等特性进行研究和分析的一门科学。角膜的生物力学特性是影响角膜屈光手术可预测性及稳定性的重要因素之一,且与不同的手术方式和切削深度相关,如板层切削较表层切削对角膜硬度影响大,厚角膜瓣术后角膜滞后量和阻力因子均较术前显著下降,切削深度大者角膜阻力因子明显下降。这些改变与术后发生角膜扩张、屈光回退等并发症有高度相关性。     

飞秒激光用于角膜屈光手术应注意的问题

虽然大量的临床数据显示飞秒激光辅助下角膜屈光手术治疗屈光不正安全、可靠,但尚需在视觉质量上与常规方法相比较来证实。在飞秒激光角膜屈光手术中合理选择手术适应证,注意操作要点,个性化选择手术方案,防范并发症的发生是提高患者视觉质量的重要前提。（眼科, 2014, 23： 289-291）     

规避潜在圆锥角膜对角膜屈光手术影响的方法

圆锥角膜是一类以角膜形态呈圆锥形前突并且角膜变薄为特征的非炎症性疾病。典型临床表现的圆锥角膜诊断比较容易,但要辨别早期潜在圆锥角膜较为困难,未被发现的角膜膨隆在角膜屈光手术后可发生进行性角膜扩张,常导致严重后果。因此为规避早期潜在圆锥角膜对角膜屈光术后的影响,可从不同方面运用多项检测系统辅助诊断,于术前筛查潜在圆锥角膜,更有利于开展角膜屈光手术并能有效预防术后并发症的发生。     

准分子激光角膜屈光手术的发展趋势

随着飞秒激光定制薄角膜瓣技术、改良表层切削技术、波阵面像差与角膜地形图引导技术、眼球定位及联机跟踪技术,以及老视补偿技术的不断改进和广泛应用,未来5～10年,准分子激光角膜屈光手术仍将是屈光手术的主流.术前筛选出亚临床圆锥角膜,是预防屈光手术后角膜扩张及继发性圆锥角膜的关键.为保持角膜生物力学的完整性和更好的视觉质量,可选择有晶状体眼人工晶状体植入术矫治超高度近视.     

角膜屈光矫正手术后白内障手术

目的:探讨角膜屈光矫正手术后白内障手术的诊疗特点。方法:对2005/2008年间于我院就诊的4例角膜屈光矫正手术后白内障患者行白内障超声乳化吸出术+人工晶状体植入术。依据患者提供的角膜屈光手术资料,分别采用临床病史法或角膜后表面曲率法计算矫正角膜曲率及人工晶状体度数。术后随访观察角膜情况、手术并发症、裸眼视力、最佳矫正视力、术后屈光状态等。结果:术后最佳矫正视力较术前明显提高。术后稳定屈光度与手术前预留屈光状态比较误差范围为-1.00～+1.25D。结论:对角膜屈光手术后的白内障患者施行白内障超声乳化吸出术+人工晶状体植入术是可行的。然而只有了解这类患者病情特点,掌握手术前后诊疗方法,准确计算人工晶状体度数,才能达到满意的疗效。     

近视激光角膜屈光术后屈光回退机制与药物防治的研究进展

激光角膜屈光手术作为矫治近视的有效方法，其术后长期稳定性是医生及患者所共同关注的问题。然而，屈光回退仍是术后常见的远期并发症之一，对于术后的屈光状态及视觉质量都有较大影响。屈光回退可能与角膜上皮及基质重塑、角膜生物力学与眼压失衡等因素有关。尽管增效手术可达到治疗屈光回退的目的，但存在角膜扩张等风险。某些降眼压药物可望重新建立眼压与角膜生物力学的平衡关系，并通过影响角膜上皮厚度以防治术后屈光回退。降眼压药物的选择、作用时间与方式等，均可能对屈光回退的防治效果产生一定影响。     

Corneal refractive surgery combined with simultaneous corneal cross‐linking: Indications,protocols and clinical outcomes—A review

Corneal refractive surgery is one of the most common approaches for correction of refractive errors. Combined corneal refractive surgery and corneal cross‐linking (CXL) has been proposed as a method to achieve better refractive stability and to prevent iatrogenic corneal ectasia. However, there are concerns regarding its indications, surgical safety, standardization of protocols and long‐term effect on corneal tissue. This review article aims to discuss the current knowledge and recent updates on combination of CXL and refractive surgery.     

应重视准分子激光角膜屈光手术对角膜生物力学结构完整性的影响

准分子激光角膜屈光手术,仍然是屈光手术的主流术式,角膜扩张或继发性圆锥角膜是术后严重的并发症之一,其主要原因为角膜生物力学结构完整性遭受破坏.保持正常角膜生物力学结构的完整性,是维持手术疗效及长期稳定性与安全性的基础.合理的手术适应证、术式选择及围手术期用药,对于保持术后角膜生物力学的完整性、避免屈光回退、角膜扩张甚至继发性圆锥角膜的风险均具有十分重要的意义.

Abstract：

Until now, in the territory of surgical methods, excimer laser refractive surgeries have being the main stream for correcting the ametropic eyes. The main cause of iatrogenic corneal ectasia and keratoconus, one of the most severe complications of corneal refractive surgeries, is the destruction of corneal biomechanics. Keeping corneal biomechanical integrality is the basis for long term effectiveness, stableness,and safety of the corneal refractive surgeries. The reasonable indication and surgical method decision,perioperative medical cares play very important roles in preventing those severe complications.     

LASIK complications: etiology, management, and prevention

Laser in situ keratomileusis (LASIK) is a rapidly evolving ophthalmic surgical procedure. Several anatomic and refractive complications have been identified. Anatomic complications include corneal flap abnormalities, epithelial ingrowth, and corneal ectasia. Refractive complications include unexpected refractive outcomes, irregular astigmatism, decentration, visual aberrations, and loss of vision. Infectious keratitis, dry eyes, and diffuse lamellar keratitis may also occur following LASIK. By examining the etiology, management, and prevention of these complications, the refractive surgeon may be able to improve visual outcomes and prevent vision-threatening problems. Reporting outcomes and mishaps of LASIK surgery will help refine our approach to the management of emerging complications.     

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.     

Scientific and rational performance of corneal refractive surgery

Domestic corneal refractive surgery is embarking on a steady development stage, and following the introduction of femto-second laser, which will open up a new era of corneal surgery. Facing new historical opportunity and challenge, it is vital for scientifical and healthy performance of the surgery both concerning on the improvement of visual quality and preventing the occurrence of complications. Only under a harmony and healthy environment, we will achieve the win-win situation between doctors and patients and sustainable development of corneal refractive surgery in the future.     

Caution to perform excimer laser corneal ablation on the ametropia with corneal guttata

It is very important to avoid inadequate patients to perform excimer laser keratectomy in order to prevent from surgical complications. The ametropic eyes with corneal guttata is considered very carefully whether to perform excimer laser corneal ablation or not, especially for the patient with corneal guttata companied by Fuchs endothelial dystrophy family history is contraindicated to perform laser corneal refractive surgery.