准分子激光原位角膜磨镶术后角膜后表面Diff值的变化

目的 探讨近视患者准分子激光原位角膜磨镶术（LASIK）术后角膜后表面Diff值变化规律及其对术后视力的影响.方法 对62例（123眼）近视患者于LASIK术前、术后1 d、1周、1个月行角膜地形图检查.分别按照残余基质床厚度、残余基质床厚度占术前角膜厚度的比例及术前屈光度的不同分组,分析各组间及同一组不同时期角膜地形图后表面Diff值的改变及其与术后视力的关系.结果 术后后表面Diff值较术前增大,且随原屈光度增大而增加,随基质床厚度增大而减小.当残余基质床厚度〉300μm或残余基质床厚度占术前角膜厚度的比例≥55%时,后表面Diff值明显减小.术后后表面Diff值与视力呈一定程度负相关.结论 LASIK术后角膜后表面前凸是影响术后视力的原因之一.后表面前凸的主要影响因素包括术前屈光度的高低、残余基质床厚度等,残余基质床厚度在300 μm以上或残余基质床厚度占术前角膜厚度的比例≥55%也许更安全.     

准分子激光原位角膜磨镶术后角膜后表面曲率的改变

LASIK术后角膜层间反应轻,角膜瓣与瓣下基质之间不形成瘢痕组织,角膜的愈合方式虽然保留了清晰的视觉光区,但是角膜的组织结构发生改变可能是导致角膜强度发生变化的主要原因。LASIK术后角膜后表面曲率均有不同程度的向前凸,这与角膜中央厚度、残余角膜基质床的厚度、矫正的屈光度数、术前眼压、角膜瓣厚度、切削深度、切削区的直径、年龄等有关。本文就LASIK术后角膜后表面曲率的变化及影响因素展开综述。     

准分子激光原位角膜磨镶术术后早期角膜空间变化

目的研究和分析近视性准分子激光原位角膜磨镶术(laser in stitu keratomileusis,LASIK)术后角膜空间变化规律。方法采用眼前节扫描系统(ORBSCANⅡ)观察48例(89眼)LASIK术前及术后1~3 d、第1周、第1个月、第3个月、第6个月的角膜前后表面高度和角膜最薄厚度的变化。结果术后角膜前表面高度迅速变平,到第1周时达最大量,此后至术后第6个月缓慢回升;术前等效球面镜度数和角膜基质床厚度与术后第3个月的角膜前表面高度变化呈直线正相关,切削比百分数(切削厚度占最薄角膜厚度比)与之呈直线负相关。LASIK术后角膜后表面即前凸,并达最大量,术后第1周时较快回落,此后至术后第6个月缓慢回落;术前等效球面镜度数、术前最薄角膜厚度、角膜基质床厚度与术后第3个月角膜后表面高度变化呈直线负相关,切削比百分数与之呈直线正相关。术后1~3 d角膜最薄,厚度最小,随着时间延长至术后第6个月均逐渐增厚,但速度逐渐减慢;术后1~3 d的实际角膜最薄厚度平均为(424±65.0)μm,比预计角膜最薄厚度平均值(463.9±42.1)μm低,差异有显著性(t=3.218,0.001相似文献   

准分子激光原位角膜磨镶术后角膜后表面的改变

目的 :研究准分子激光原位角膜磨镶术 (LASIK)后角膜后表面的改变 ,分析角膜后表面变化的相关影响因素。方法 :对 5 3例 96只眼施行LASIK手术 ,术前与术后 1个月使用裂隙扫描角膜地形图系统检测角膜后表面的高度及屈光度差异 ,分析角膜后表面前凸量与术前等效球镜度数、角膜中央厚度、术前眼压、激光切削量、切削百分比等因素的关系。结果 :LASIK术后 ,角膜后表面平均前凸量为 (33.4±2 4 .4 ) μm ,平均屈光度变化量为 (- 0 .6 7± 0 .4 2 )D ,术前术后的变化均具有显著性。与前凸量相关的可解释变量为术前角膜厚度 (偏回归系数B =- 0 .4 4 7,P <0 .0 0 0 1)、切削比 (B=15 4 .77,P =0 .0 0 1)和术前眼压 (B =2 .0 31,P =0 .0 2 4 )。结论 :LASIK术后角膜后表面普遍存在轻微的前凸 ,角膜较薄、眼压较高及切削比较大的受试眼术后角膜后表面前凸程度更大。     

LASIK术后角膜基质床厚度影响因素的析因设计研究

目的:采用析因设计法探讨LASIK术角膜基质床厚度的主要影响因素间的关联及实用性。方法:选取眼科门诊接受LASIK术患者30例60眼,以术前眼压、屈光度、术后角膜基质床厚度为研究因素进行析因设计试验。结果:术前屈光度间、术前眼压与术前屈光度之间差异无统计学意义(P>0.05);术前眼压间(P<0.05)、术前眼压与术后角膜基质床厚度之间(P<0.01)及术前屈光度与术后角膜基质床厚度之间(P<0.01)差异有统计学意义。术前眼压、屈光度、术后角膜基质床厚度间存在交互影响(P<0.01)。结论:析因设计法可用于眼科专业中多因素多水平的研究;术前眼压、屈光度、术后角膜基质床厚度是影响LASIK术成功与否的重要因素,在术前眼压<21mmHg、术前屈光度中度、术后角膜基质床厚度保留300μm以上较安全。     

三种准分子激光手术中角膜切削厚度的对比研究

目的 通过术中利用光学相干厚度测量的方法评估飞秒激光制瓣联合LASIK、LASIK与LASEK三种手术中角膜切削深度的差异。设计 前瞻性比较性病例系列。研究对象 2013年3月到2014年5月行阿玛仕准分子激光矫正手术的患者103例200眼,其中飞秒激光制瓣LASIK组50例100眼,角膜板层刀LASIK组30例57眼,LASEK组23例43眼。方法 术中使用实时角膜厚度测量（OCP）技术分别测量制瓣后激光切削前和激光切削后的中央角膜厚度,从而计算实际角膜基质切削深度。比较各组实际角膜切削深度与激光系统预期最大切削深度的差异及三种术式实际角膜切削深度与理论切削深度差值的组间差异。主要指标 理论角膜切削深度、实际角膜切削深度。结果 飞秒激光制瓣LASIK组OCP所测角膜切削深度（117.22±31.13）μm,准分子激光系统预计角膜切削深度（99.52±25.47）μm（t=-12.55,P<0.001）。角膜板层刀制瓣LASIK组OCP所测角膜切削深度（116.30±22.93）μm,预计角膜切削深度（94.26±16.37）μm （t=-12.44,P<0.001）。LASEK组OCP所测角膜切削深度（106.72±23.77）μm,预计角膜切削深度（99.31±20.46）μm（t=-4.44,P<0.001）。实际角膜切削深度与预计值比较,飞秒激光制瓣LASIK组为（17.69±14.10）μm,角膜板层刀制瓣LASIK组为（22.04±13.38）μm,LASEK组为（7.41±10.95）μm。飞秒激光制瓣及板层刀制瓣LASIK组实际角膜切削深度与理论切削深度差值较LASEK术式组切削深度差值较大（P均<0.001）。飞秒激光组与角膜板层刀组之间差异无统计学意义（P=0.15）。结论 术中实时光学相干厚度测量的方法所测三种准分子激光手术实际角膜切削深度较激光系统预计值大,术前预测角膜基质床厚度时需考虑到预计值与实际值差值存在。（眼科, 2014, 23： 305-307）     

高度近视患者LASIK术后角膜后表面曲率变化的析因分析研究

目的观察准分子激光原位角膜磨镶术（LASIK）术后角膜后曲率的变化,并研究角膜后表面曲率变化与术前眼压及承载因子（术前角膜中央厚度/残留角膜基质床厚度）的关系。方法采用ORBSCANⅡ裂隙扫描角膜地形图系统对高度近视患者40例（80只眼）LASIK术前和术后1、2、3个月及6个月的角膜后表面曲率进行测定,分析LASIK术后角膜后表面曲率的变化,并按术前眼压及承载因子分成4组,对LASIK术后角膜后表面曲率变化与术前眼压、承载因子进行析因分析研究。结果高度近视眼LASIK术后角膜后表面均有不同程度的向前膨隆,LASIK术后1个月较术前角膜后表面曲率半径变化为（0.135±0.098）μm,LASIK术后2个月较术后1个月角膜后表面曲率半径变化为（0.022±0.034）μm。结论高度近视眼LASIK术后早期角膜后表面均有不同程度的向前膨隆,LASIK术后2个月时角膜后表面曲率基本稳定。且术前眼压越高、承载因子越大,术后角膜膨隆越明显。     

角膜厚度和角膜曲率对LASIK术后眼压测量值的影响

目的探讨准分子激光原位角膜磨镶术（LASIK）后角膜厚度和角膜曲率对眼压测量值的影响。方法150例（285眼）近视行LASIK并随访1年，对手术前后的角膜厚度、角膜曲率及眼压进行统计学分析。结果LASIK术后3、6、12个月的角膜厚度、角膜曲率及眼压测量值均较术前明显下降（P〈0．01）。术前及术后3、6、12个月的眼压测量值与角膜厚度、角膜曲率呈正相关。结论LASIK术后眼压测量值低于术前，眼压测量值与角膜厚度和角膜曲率均呈正相关，角膜厚度和角膜曲率是眼压测量值的影响因素。     

LASIK术后角膜后表面稳定性分析

目的:探讨近视眼准分子激光原位角膜磨镶术(laser in situ keratomileusis,LASIK)对角膜后表面稳定性的影响。方法:采用Orbscan-Ⅱz及Pentacam眼前节分析仪测量近视眼LASIK手术前、手术后1wk;1,3,6mo的角膜后表面高度,统计分析其术前、术后变化情况。结果:Orbscan-Ⅱz测量发现LASIK术后角膜后表面向前膨隆(P=0.000),且与术前近视度数、中央角膜厚度呈负相关(r=-0.403,P=0.001;r=-0.349,P=0.004)和切屑深度呈正相关(r=0.411,P=0.001)。Pentacam测量结果显示LASIK术后角膜后表面并未发生前移或后移(P>0.05)。结论:LASIK术后角膜后表面并未发生前凸等改变,Orbscan-Ⅱz眼前节分析系统测量结果显示的LASIK术后角膜后表面前凸可能是因为LASIK手术改变了角膜对Orbscan检查设备成像系统的放大效应。     

影响LASIK术后角膜后表面稳定性的相关因素

目的：探讨影响准分子激光原位角膜磨镶术( laser in situ keratomileusis,LASIK )术后角膜后表面稳定性的相关因素。
　　方法：对来我院行LASIK手术的患者64例64眼分析术后6mo后表面变化与制瓣方式、角膜瓣厚度( flap thickness, FT)、切削厚度( ablation thickness,AT)、术后剩余基质厚度( postoperative residual corneal stroma thickness, RCST )、术前角膜最薄点厚度( preoperative thinnest corneal thickness,CT)、角膜瓣厚度/术前角膜最薄点厚度( flap thickness/ preoperative thinnest corneal thickness, FT/CT )、切削厚度/术前角膜最薄点厚度( ablation thickness/preoperative thinnest corneal thickness, AT/CT )、剩余基质厚度/术前角膜最薄点厚度( postoperative residual corneal stroma thickness /preoperative thinnest corneal thickness, RCST/CT)、术前角膜地形图(前表面高度、后表面高度、后表面diff值)和术前眼压的相关性。
　　结果：本研究表明手术前后角膜后表面diff差值与屈光度(r=0.419,P=0.014),AT(r=0.394,P=0.023),AT/CT(r=0.501,P=0.004),术前角膜后表面diff值(r=0.501,P=0.004),RCST(r=-0.385,P=0.033)和RCST/CT(r=-0.401, P=0.025)相关。手术前后角膜后表面高度差值与屈光度(r=0.520,P=0.002),AT(r=0.504,P=0.003),AT/CT(r=0.442,P=0.013),角膜后表面diff值(r=0.624,P=0.000)和RCST/CT(r=-0.394,P=0.028)相关。
　　结论：AT,RCST,AT/CT,RCST/CT和术前角膜地形图后表面diff值应作为预测术后角膜后表面稳定性的关键性指标,但具体安全限度值有待进一步研究。     

Factors affecting the forward shift of posterior corneal surface after laser in situ keratomileusis

PURPOSE: To evaluate the anteroposterior movement of the corneal back surface after laser in situ keratomileusis (LASIK). DESIGN: Retrospective noncomparative case series. PARTICIPANTS: One hundred ninety-six eyes of 120 subjects with myopic refractive errors of -2.0 to -12.5 diopters. INTERVENTION: LASIK was performed. Corneal topography of the posterior corneal surface was obtained with the scanning slit topography system before and 1 month after surgery. MAIN OUTCOME MEASURES: The amount of forward shift of the posterior corneal surface was determined. Multiple regression analysis was used to assess the factors that affect the forward shift of the posterior corneal surface. RESULTS: After surgery, the posterior corneal surface displayed mean forward shift of 40.9 +/- 24.8 micrometer. Explanatory variables relevant to the forward shift of corneal posterior surface were, in the order of magnitude of influence, the amount of laser ablation (partial regression coefficient B = 0.561, P < 0.0001), preoperative corneal thickness (B = -0.176, P = 0.00096), and preoperative intraocular pressure (B = 1.676, P = 0.0053). Preoperative refraction and achieved myopic correction showed collinearity with the amount of laser ablation. CONCLUSIONS: LASIK induces a forward shift of the cornea. Eyes with thinner corneas, higher intraocular pressure, and higher myopia requiring greater laser ablation are more predisposed to the anterior shift of the cornea.     

Early spatial changes in the posterior corneal surface after laser in situ keratomileusis

PURPOSE: To evaluate the forward shift of the posterior corneal surface after myopic laser in situ keratomileusis (LASIK) relative to the residual stromal bed thickness and the ablation percentage of the total corneal thickness. SETTING: Department of Ophthalmology, Ilsan Paik Hospital, Inje University, Ilsan, Korea. METHODS: Three hundred sixty-three eyes of 182 consecutive patients who had LASIK were examined retrospectively. The range of the refractive errors was -1.5 to -12.0 diopters. Corneal topography using Orbscan II (Bausch & Lomb) and pachymetry were obtained preoperatively and 1 week and 1, 2, and 3 months postoperatively. The patients were divided into 4 groups based on the residual stromal bed thickness: Group 1, 145 eyes with less than 250 microm; Group 2, 129 eyes with 250 to 300 microm; Group 3, 76 eyes with 300 to 350 microm; and Group 4, 13 eyes with more than 350 microm. They were also grouped by the ablation percentage per total corneal thickness: Group A, 16 eyes with less than 10%; Group B, 166 eyes with 10% to 20%; Group C, 146 eyes with 20% to 30%; and Group D, 35 eyes with more than 30%. RESULTS: The increase in the forward shift of the posterior corneal surface postoperatively correlated with the residual corneal bed thickness and the ablation ratio per total corneal thickness. There were no statistically significant changes in the postsurgical forward shift of the posterior corneal surface if the residual corneal thickness remained greater than 350 microm or the ablation percentage was less than 10%. CONCLUSIONS: Increased forward shift of the posterior corneal surface is common after myopic LASIK and correlates with the residual corneal thickness and the ablation percentage per total corneal thickness. An excessively thin residual corneal bed or a large ablation percentage may increase the risk of iatrogenic complications.     

Residual bed thickness and corneal forward shift after laser in situ keratomileusis

PURPOSE: To prospectively assess the forward shift of the cornea after laser in situ keratomileusis (LASIK) in relation to the residual corneal bed thickness. SETTING: Miyata Eye Hospital, Miyazaki, Japan. METHODS: Laser in situ keratomileusis was performed in 164 eyes of 85 patients with a mean myopic refractive error of -5.6 diopters (D) +/- 2.8 (SD) (range -1.25 to -14.5 D). Corneal topography of the posterior corneal surface was obtained using a scanning-slit topography system before and 1 month after surgery. Similar measurements were performed in 20 eyes of 10 normal subjects at an interval of 1 month. The amount of anteroposterior movement of the posterior corneal surface was determined. Multiple regression analysis was used to assess the factors that affected the forward shift of the corneal back surface. RESULTS: The mean residual corneal bed thickness after laser ablation was 388.0 +/- 35.9 microm (range 308 to 489 microm). After surgery, the posterior corneal surface showed a mean forward shift of 46.4 +/- 27.9 microm, which was significantly larger than the absolute difference of 2 measurements obtained in normal subjects, 2.6 +/- 5.7 microm (P<.0001, Student t test). Variables relevant to the forward shift of the corneal posterior surface were, in order of magnitude of influence, the amount of laser ablation (partial regression coefficient B = 0.736, P<.0001) and the preoperative corneal thickness (B = -0.198, P<.0001). The residual corneal bed thickness was not relevant to the forward shift of the cornea. CONCLUSIONS: Even if a residual corneal bed of 300 microm or thicker is preserved, anterior bulging of the cornea after LASIK can occur. Eyes with thin corneas and high myopia requiring greater laser ablation are more predisposed to an anterior shift of the cornea.     

传导性角膜成形术后角膜后表面的改变

目的:探讨传导性角膜成形术(conductive keratoplasty,CK)后角膜后表面的改变及其相关影响因素。方法:接受CK的老视患者30例(36眼),术前及术后1mo采用裂隙扫描角膜地形图系统检测角膜后表面的高度及屈光度差异,分析角膜后表面改变的相关影响因素。结果:CK术后角膜后表面平均前凸量为(32.7±20.4)μm,平均屈光度变化为(-0.64±0.40)D,和术前比较差异均有显著性意义。术前中央角膜厚度、眼压及拟矫正屈光度和角膜后表面前凸有关。结论:CK术后角膜后表面存在轻微的前凸。角膜较薄、眼压较高及拟矫正屈光度较大的受试眼术后角膜后表面前凸程度更大。     

准分子激光原位角膜磨镶术术后早期应用卡替洛尔滴眼液对屈光状态的影响

目的 评估准分子激光原位角膜磨镶术（LASIK）术后早期应用盐酸卡替洛尔滴眼液对屈光状态及眼压的影响。 设计 前瞻性比较性病例系列。研究对象 2009年11月-2011年9月北京同仁医院行LASIK手术的近视患者32例（32眼）。 方法 试验组15眼LASIK术后第1周开始使用2%盐酸卡替洛尔滴眼液每日2次,低中度近视患者持续1个月,高度近视患者持续1.5个月。对照组17眼术后不使用2%盐酸卡替洛尔滴眼液。术前、术后1、3、6个月进行显然验光、Oculyzer眼前节测量系统、眼压等检查。主要指标 等效球镜度、角膜后表面高度、眼压。结果 试验组术后1、3、6个月时等效球镜度分别为（-0.150±0.742）、（-0.170±0.595）和（-0.525±0.618）D;对照组分别为（-0.258±0.581）、（-0.290±0.657）和（-0.459±0.591）D（P均＞0.05）。试验组术后1、3、6个月时角膜后表面高度分别为（7.47±2.326）、（6.60±3.158）和（5.86±2.610）μm;对照组分别为（6.59±3.355）、（7.35±3.622）和（7.33±2.992）μm（P均＞0.05）。试验组术后1、3、6个月眼压分别为（7.80±0.941）、（8.07±1.534）、（8.70±1.337） mm Hg;对照组分别为（9.35±2.827）、（9.59±2.717）、（8.73±1.580）mm Hg。术后1个月时试验组和对照组眼压有统计学差异（P=0.045）,余时间点均无统计学差异。结论 LASIK术后早期应用盐酸卡替洛尔滴眼液通过降低眼压可能对屈光状态具有稳定作用。（眼科,2013,22：49-52）     

Theoretical elastic response of the cornea to refractive surgery: risk factors for keratectasia

PURPOSE: To explore the role that mechanical elastic factors may have in post-refractive surgery corneal phenomena, from mild curvature changes to keratectasia. METHODS: The central cornea near the apex was modeled as an elastic spherical thin shell loaded by the intraocular pressure (IOP). Equations for myopic laser in situ keratomileusis (LASIK) were obtained to estimate shifts and curvature changes of the posterior corneal surface at the apex. The effect of every parameter was studied, identifying potential risk factors for ectasia. RESULTS: Theoretically, corneal thinning by ablation will produce an elastic deformation of the posterior surface that depends on the corneal parameters (curvature, Young's modulus, Poisson ratio, and thickness), the IOP, and the ablation profile. In particular, a forward shift and an increase in power of the posterior surface was predicted for myopic LASIK, in agreement with previous experimental findings. These changes rise non-linearly with the attempted correction, and are greater for thinner preoperative corneas, higher IOP smaller Young's modulus, and thicker flaps. Corneas with Young's modulus half the average or less, or thickness <500 microm, may present high risk of ectasia, especially for high IOP and thick flaps. CONCLUSIONS: Some postoperative effects may be explained in part by elasticity. Research efforts are needed to explain other biomechanical behaviors. The accepted criterion of 250 microm residual bed is insufficient for fine patient screening--depending on the individual ocular parameters, it could be more restrictive. Advances in technology are needed to create a preoperative examination including two-dimensional maps of topography, pachymetry, and Young's modulus.     

近视LASIK术后角膜后表面前凸的影响因素

目的:探讨准分子激光原位角膜磨镶术(laser in situ keratomileusis,LASIK)后影响OrbscanⅡ中角膜后表面前凸量(后表面Diff值)的主要因素。方法:选取120例240眼近视患者眼行LASIK术,应用Orbscan-Ⅱ角膜地形图于术前和术后1,3,6,12mo分别检测术前和术后角膜后表面Diff值,统计分析影响术后Diff值的主要因素。结果:逐步回归方程分析,切削百分比和术前角膜后表面Diff值是术后各时期Diff值的影响因素,术前眼压也是影响术后1mo时Diff值的因素之一。结论:认为LASIK术前重视角膜后表面前凸量,并在保证手术效果的情况下控制切削百分比,同时在术后严密监测眼压,必要时降低患眼眼压,可以尽量避免术后角膜扩张、屈光回退等并发症的发生。