角膜激光矫正术后上皮重塑的研究进展

角膜上皮细胞具有重塑性,角膜激光手术后,为了维持角膜前表面的光滑,上皮细胞重新排列,上皮厚度在不同区域和象限呈现不均匀分布。角膜上皮厚度的变化幅度受拟矫正屈光度、手术方式、眼表状态等因素的影响。角膜上皮重塑与术后的屈光回退有一定的相关性。认识角膜激光矫正术后上皮重塑的规律有助于提高屈光手术的精确性。现笔者对目前角膜上皮...     

屈光手术后角膜上皮厚度的变化规律及影响因素

人类角膜上皮具有较强的重塑能力, 当角膜表面呈现不规则形态时, 角膜上皮会以增厚的形式在一定程度上重塑角膜。角膜屈光手术后角膜形态发生改变, 这种变化会刺激角膜上皮细胞重新排列, 呈现出角膜上皮厚度的变化。角膜上皮增厚的程度与手术方式、屈光不正的矫正量、切削深度和切削区域相关:经上皮准分子激光屈光性角膜切削术(transepithelial photorefractive keratectomy, Trans-PRK)后1个月表现出明显的角膜上皮增厚且增厚区域主要在周边区;飞秒激光辅助原位角膜磨镶术(femtosecond laser-assisted in situkeratomileusis, FS-LASIK)和飞秒激光小切口微透镜取出术(femtosecond laser small incision lenticule extraction, SMILE)在术后1周就表现出明显的角膜上皮增厚, 不同的是FS-LASIK增厚区域主要为旁中央区, 而SMILE增厚区域为周边区。角膜上皮厚度的变化对术后视力恢复、术后屈光度的预测以及对角膜屈光稳定性的影响不容忽视。(国际眼科纵览, ...     

LASIK术后早期角膜上皮改变的共焦显微镜观察

目的 评价LASIK术后不同时间角膜中央上皮厚度变化，探讨上皮厚度变化与屈光状态之间的关系。方法 设计自身配对研究。选择2002年11月29日至2003年1月24日于天津医科大学眼科中心屈光手术门诊进行原位角膜磨镶术病例24例(48眼)，分别在术前、术后第1、3、7、10、30、60、90天，观察屈光状态的变化，应用活体共聚焦显微镜(Confoscan 3．0)测量中央角膜上皮厚度，并对上皮厚度变化与屈光状态的相关性进行分析。结果 与术前相比，LASIK术后角膜上皮厚度平均增加了10．7％。等效球镜度数变化与上皮厚度的变化呈正相关(r=0．538，P=0．047)。结论 LASIK术后角膜上皮厚度增加，上皮参与了早期角膜组织修复的过程。术后屈光状态变化与上皮厚度的增减有关。     

角膜上皮重塑影响因素的研究进展

角膜上皮重塑及其影响因素在临床实践中受到越来越多的关注。角膜上皮细胞具有独特的重塑能力, 能够对角膜基质和曲率的变化作出反应, 通过局部性的增厚或变薄来适应不同状态, 以维持眼表的稳定性和清晰的视觉。值得注意的是, 这种重塑能力是非均匀的, 且受多种内外因素影响。因此, 标准化评估角膜上皮厚度变化对于深入理解角膜上皮重塑过程至关重要。现笔者探讨不同眼表疾病、屈光手术方式和药物对角膜上皮重塑的影响, 以期能协助临床医师进行相关疾病的早期诊疗, 提高屈光手术的精确性。     

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。     

角膜屈光术后眼压测量方法及影响因素的研究进展

角膜屈光术后由于角膜厚度、角膜生物力学的改变，术后眼压测量值较真实眼压有偏差。角膜屈光术后眼压的准确评估在临床工作中至关重要。术后眼压测量受到眼压计、角膜厚度、角膜滞后量及角膜阻力因子等因素的影响。现就角膜屈光手术后眼压测量方法及影响因素进行综述。     

角膜伤口愈合与角膜屈光手术

角膜伤口愈合的状况直接影响角膜屈光手术的预后。任何角膜屈光手术后，必须有良好的上皮愈合。上皮基底膜和Ｂｏｗｍａｎ氏层损伤会影响上皮的再覆盖。上皮糜烂和上皮下长可能导致手术失败。实质层的愈合，与切口形态及缝合等因素有关。愈合过程经历一系列基质和细胞的变化，其每一环节都将影响伤口愈合的结果。不同术角膜屈光手术也有其愈合的特殊性。若屈光手术成功，应当控制伤口愈合。     

角膜基质透镜植入联合角膜胶原交联术治疗圆锥角膜术后角膜上皮重塑

目的：观察飞秒激光辅助下的角膜基质透镜植入联合角膜胶原交联术(SLAK-CXL)治疗进展期圆锥角膜术后角膜上皮重塑情况，探讨角膜上皮重塑规律和影响因素，为进一步屈光矫正提供良好的时机选择。

方法：回顾性、观察性研究。纳入2020-09/2021-10于我院接受SLAK-CXL的圆锥角膜患者28例29眼，记录手术前后视力、眼压(IOP)、屈光度、角膜曲率及角膜上皮厚度(CET)，观察CET变化趋势，并根据透镜厚度和植入深度分析影响CET变化的因素。

结果：与术前比较，纳入患者术后1mo角膜前表面曲率平坦值(K_f)和陡峭值(K_s)均升高(P<0.05)，术后1、2、6mo，1a角膜最薄点厚度(TCT)均升高(P<0.05)。纳入患者术后CET随时间变化而变化，中央区CET变化趋势较明显。与术前相比，术后1、2、6mo，1a旁中央区上方、鼻上方、鼻侧和颞上方CET均降低，中周区上方、颞侧、颞上方CET均降低，外周区鼻上方CET均增加。术后1a，不同植入透镜深度和厚度患者各分区角膜上皮厚度变化量均无差异(P>0.05)。

结论：首次发现SLAK-CXL治疗圆锥角膜术后角膜形态发生变化，CET呈先减少再增加再减少趋势，术后1a中央区、旁中央区CET降低，中周区、外周区CET增加，且角膜上皮重塑程度与术中植入透镜深度和厚度均无关。     

角膜屈光术后角膜瓣下上皮细胞植入的研究进展

角膜瓣下上皮细胞植入或内生是角膜屈光术后并发症之一,近年来随着手术设备和技术的提高,其发生率已经明显降低。但外伤致角膜瓣移位发生角膜瓣下上皮植入病例仍时有报道。若上皮细胞植入处理不及时可引起患者屈光状态改变、角膜瓣融解等严重并发症。故本文对角膜屈光术后角膜层间上皮植入研究进展予以综述。     

角膜屈光手术医师应注意抗炎类滴眼液对术后角膜生物力学的影响

伴随科学技术的进步，角膜屈光手术疗效得到了不断的提高，人们在改善患者视觉质量的同时，也关注到角膜屈光手术后角膜生物力学改变带来的影响。角膜生物力学相关参数不但受角膜屈光手术的直接影响，同时也受到人体生理周期以及术后一些药物的影响，而这些影响是导致部分手术疗效不“稳定”的重要因素。手术对角膜生物力学的影响已受到了较多的关注，但对于术后部分抗炎类滴眼液的应用可能引发眼压升高、屈光回退、甚至视觉质量下降等了解尚不够。本文对抗炎类滴眼液在角膜屈光手术后局部应用的作用及其不良反应进行阐述，特别是角膜屈光手术后角膜生物力学变化的特点，以及部分抗炎类滴眼液应用后眼压升高对术后角膜生物力学进一步的影响进行讨论，提出了角膜屈光手术医师应加强抗炎类滴眼液对术后角膜生物力学潜在影响的重视。     

Short-term effects of proparacaine on human corneal thickness.

.5% proparacaine HCl is commonly used for topical anaesthesia in ultrasound pachometry prior to refractive surgery. This drug is known to alter corneal epithelial adhesion. Does 0.5% proparacaine result in an alteration in corneal thickness due to changes in the corneal epithelium? Corneal thickness was measured by optical pachometry at 30 sec intervals for 15 min under 3 experimental conditions; 1) 2 drops of artificial tears, 2) 1 drop of 0.5% proparacaine, 3) 2 drops of 0.5% proparacaine. Baseline measurements were recorded before each trial. No significant differences were found between the mean corneal thicknesses measured in the baseline, 2 drops of artificial tears and 1 drop of 0.5% proparacaine conditions. The mean corneal thickness in the 2 drops of 0.5% proparacaine condition was significantly greater than those measured in the other conditions. In particular the measured corneal thickness was significantly different from the baseline measurements 1 to 2 min after instillation of the 2 drops of 0.5% proparacaine. Exponential modelling of the corneal edema recovery function demonstrated that recovery to baseline corneal thickness occurred 7 to 8 min following the instillation of 2 drops of 0.5% proparacaine. The data of this study suggest that only 1 drop of 0.5% proparacaine should be used for topical anaesthesia prior to ultrasound pachometry. This recommendation may minimize the possibility of measuring artifactually large corneal thickness estimates, and thus reduce the possibility of corneal microperforation during refractive surgery.     

三种不同设备行屈光手术时的角膜切削误差比较

目的调查2种不同的准分子激光设备和1种全飞秒激光手术设备用于准分子激光原位角膜磨镶术（LASIK）时对中央角膜厚度切削误差的影响,探索角膜切削误差的变化规律。方法前瞻性病例对照研究。使用A型超声角膜测厚仪测量分别应用3种不同设备行手术治疗的138例（274眼）患者术前及术后1个月的中央角膜厚度。其中51例（100眼）使用Esiris机器行LASIK手术（Esiris—LASIK）,50例（100眼）使用VisxS4-IR机器行LASIK手术（Visx—LASIK组）,37例（74眼）使用VisuMax机器行SMILE手术（VisuMax—SMILE组）。所有眼按屈光度分为低、中、高度3组,分别计算中央角膜厚度及角膜切削误差,并分析切削误差与不同设备、近视程度、散光程度、角膜切削直径及手术前角膜厚度的关系。采用单样本t检验、双因素方差分析及Pearson相关进行数据分析。结果3组病例中,近视程度、术前中央角膜厚度及术前散光度对角膜切削误差均没有显著影响,设备或手术方式对角膜切削误差有显著的影响。在Esiris—LASIK组中,角膜的实际切削厚度小于预期切削厚度,差异有统计学意义（低度近视组,t=4．672,P〈0．01;中度近视组,t=10．629,P〈0．01;高度近视组,t=11．021,P〈0．01）;Visx—LASIK组中,角膜的实际切削厚度大于预期切削厚度,差异有统计学意义（低度近视组,t=3．910,P〈O．01;中度近视组,t=4．922,P〈0．01;高度近视组,t=4．807,P〈0．01）;在VisuMax—SMILE组中,角膜的实际切削厚度与预期切削厚度差异无统计学意义（中度近视组,t=1．158,P〉O．05;高度近视组,t=0．836,P〉0．05）。结论不同的手术设备会显著影响屈光手术中中央角膜厚度的切削误差。     

Mathematical model of corneal surface smoothing after laser refractive surgery

PURPOSE: To construct a quantitative model of corneal surface smoothing after laser ablation for refractive correction. DESIGN: Experimental study, interventional case series, and meta-analysis of literature. METHODS: A theory of epithelial smoothing in response to corneal contour change is derived from differential equations that describe epithelial migration, growth, and loss. Computer simulations calculate the effects on postoperative epithelial thickness, topography, refraction, and spherical aberration. Model parameter is matched with laser in situ keratomileusis (LASIK) outcome in literature and in a retrospective study of primary spherical myopic (77 eyes) and hyperopic (19 eyes) corrections. Surgically induced refractive change was the main outcome measure. RESULTS: Simulated epithelial remodeling after myopic ablation produces central epithelial thickening, reduction in achieved correction, and induction of oblate spherical aberration. Simulation of hyperopic ablation shows peripheral epithelial thickening, a larger reduction in correction, and induction of prolate spherical aberration. Simulation using a minus cylinder laser ablation pattern shows decreased astigmatism correction and increased hyperopic shift. In the LASIK series, linear regression of achieved correction vs ablation setting in hyperopic and minus cylinder corrections shows slopes of 0.97, 0.71, and 0.74, respectively. These clinical results match model predictions when the smoothing constant is set at 0.32, 0.63, and 0.55 mm, respectively. CONCLUSIONS: Epithelial thickness modulations after ablation can be modeled mathematically to explain clinically observed regression and induction of aberration. The cornea appears to smooth over ablated features smaller than approximately 0.5 mm. The model provides an approach for designing ablation patterns that precompensate for the smoothing to improve final outcome.     

角膜厚度测量的研究进展

中央角膜厚度对角膜疾病、青光眼、角膜屈光手术等眼部疾病和手术有重要影响，获得精准的角膜中央厚度为临床医师提出了更高的要求，也是大家一直非常关注的话题。目前，临床中常用的角膜厚度测量仪器有2类原理：第一类为超声波测量，例如传统的A型超声角膜测厚仪(A超)、超声生物显微镜(UBM)； 第二类是光学测量原理，包括Pentacam眼前节分析仪、角膜内皮镜、光学相干断层扫描仪(OCT)、Lenstar LS900光学生物测量仪。不同的测量方法和相应仪器都具有各自的优点及不足。角膜厚度测量最佳的发展方向应为简单易用、重复性好、准确性高。因此对目前临床常用的角膜厚度测量仪器的原理及特点进行综述，总结当下角膜测厚的研究进展，为临床眼科医生提供理论依据和临床指导。     

角膜伤口愈合机制对准分子激光角膜屈光手术的启示

角膜伤口愈合反应是由细胞因子、生长因子、趋化因子介导的复杂级联反应。角膜上皮细胞和基底膜在这一过程中起了重要的作用,而这二者在准分子激光角膜屈光手术中常常被损伤。因此,深刻理解角膜伤口愈合过程以及并发症产生的原因,对提高准分子激光角膜屈光手术的有效性和安全性具有重要意义。就角膜伤口愈合过程及其机制进行综述。     

Toxic keratopathy-related corneal dehydration after laser in situ keratomileusis

A 33-year-old woman had progressive blurred vision 2 weeks after uneventful laser in situ keratomileusis surgery. Initial satisfactory uncorrected visual acuity (UCVA) was complicated by postoperative dry eye and drug toxicity. Slitlamp biomicroscopy revealed diffuse punctate epithelial keratitis and inferior corneal epithelial defect with rolled-up epithelium on the flaps and the inferior unoperated cornea in both eyes. Diffuse inflammatory cell infiltrates were evident in the stroma. Stromal thinning was evident on serial Orbscan (Bausch & Lomb) and pachymetry examinations, and a hyperopic shift of almost +6 diopters was observed in the refractive error in both eyes. These examinations showed a gradual recovery of stromal thickness after copious hydration with balanced salt solution. The UCVA was 1.0 in both eyes after corneal rehydration.     

准分子激光角膜屈光手术与眼压

准分子激光角膜屈光手术是目前治疗屈光不正的主要手术方式,在改善视力的同时,我们更关心眼压和准分子激光角膜屈光手术的相互关系。本文就准分子激光角膜屈光手术的分类,24h眼压波动,术前、术后角膜厚度、曲率与眼压关系,高度近视合并青光眼的诊断,屈光回退及近视进展与眼压的关系,糖皮质激素性高眼压或青光眼做一综述,对眼科临床的诊断和治疗方面都具有重要意义。     

Dynamic corneal imaging

PURPOSE: To determine the clinical practicability of in vivo dynamic corneal imaging (DCI) to assess the individual elastic properties of normal human eyes, eyes with abnormal findings, and eyes after refractive surgery. SETTING: University Eye Clinic, Paracelsus Private Medical University, Salzburg, Austria. METHODS: The DCI method uses sagittal, stepwise, central indentation of the cornea with electronically controlled microprecision motors and sequential registration of videotopography images. The indentation steps are preselected and range from 50 to 800 mum. The computerized analysis of the videotopography images captured during the process uses Zernike polynomials to establish a newly defined flexing curve for normal eyes and eyes with abnormal findings. RESULTS: Dynamic corneal imaging was done in 187 eyes of 103 patients who had clinically healthy corneas, distinct keratoconus, or previous refractive surgery. The method rapidly evaluated artificially and reversibly induced changes in corneal topography in a clinical setting using a modified Placido disk-based computer-assisted videokeratography system with a small cone. In early analysis, the flexing curve showed a significant correlation with the applied indentation depth. Factors influencing the shape of the curve were central corneal thickness, intraocular pressure, and patient age. The DCI method also allowed easy examination of keratoconic corneas and corneas after refractive surgery. CONCLUSIONS: Dynamic corneal imaging induced a reproducible and reversible change in corneal topography corresponding to the different indentation depths. The results indicate that several clinical parameters are correlated with corneal elastic behavior in vivo and that the technology could increase the predictability of refractive corneal surgery and help in the early diagnosis of corneal diseases and with newly developed therapies.