LASIK术后角膜后表面形态变化的研究

目的研究准分子激光原位角膜磨镶术（LASIK）术后角膜后表面的形态变化,探讨手术后应保留角膜的安全厚度。方法对135例（269眼）近视使用Orbscan裂隙扫描角膜地形图/角膜测厚系统,观察LASIK术后角膜后表面Diff值的变化。结果术后根据保留角膜厚度的不同分为3组,第1组保留角膜厚度〉450μm,Diff值为（0.041±0.008）mm,第2组保留角膜厚度为410～450μm,Diff值为（0.057±0.013）mm,第3组保留角膜厚度为〈410μm,Diff值为（0.080±0.014）mm。3组间比较均差异非常显著。术后保留角膜床厚度〉280μm者,角膜后表面前凸值为（0.016±0.005）mm,保留角膜床厚度〈280μm,前凸值为（0.034±0.009）mm,角膜后表面前凸值平均为（0.017±0.006）mm。结论 LASIK术后角膜后表面中央部均有不同程度的前凸。保留角膜床厚度和角膜后表面前凸值呈负相关。LASIK后角膜厚度至少应在410μm,残留角膜床厚度安全值应为280μm。     

准分子激光原位角膜磨镶术后角膜后表面高度研究

目的 观察准分子激光原位角膜磨镶术(LASIK)术后角膜后表面高度的改变,探讨角膜后表面膨隆与剩余角膜基质床厚度(RBT),以及与激光切削所占角膜厚度比例(AP/TCT)的关系.方法 回顾分析LASIK 157例(157眼),根据RBT分组:组1为79眼,RBT≥350 μm;组2为52眼,300 μm≤RBT＜ 350 μm;组3为26眼,250 μm≤RBT＜ 300 μm.根据AP/TCT分组:组A为44眼,AP/TCT≤10%;组B为84眼,10%＜AP/TCT≤20%;组C为29眼,AP/TCT＞ 20%.术前、术后1周、术后1个月、术后3个月、术后6个月应用OrbscanⅡ行角膜地形图检查,分析比较各组各个不同时间点的角膜后表面膨隆程度.结果 角膜后表面高度各组术后1周、术后1个月、术后3个月、术后6个月与术前比较,差异均有统计学意义(P均＜0.05);术后同一时间点,组1、组2、组3组间及组A、组B、组C组间角膜后表面高度差异值( PED)两两比较差异有统计学意义(P均＜0.05).术后6个月PED值与RBT呈线性负相关(r= -0.77,P=0.00);与AP/TCT呈线性正相关( r=0.90,P=0.00),且与AP/TCT相关性更好.结论 LASIK术后角膜后表面均有不同程度的膨隆,并与RBT和AP/TCT相关;RBT不应为LASIK术后评价角膜后表面膨隆风险的唯一指标,AP/TCT是重要补充指标.(中国眼耳鼻喉科杂志,2011,11:215-218)     

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.     

准分子激光原位角膜磨镶术后角膜后表面屈光力变化

目的 探讨准分子激光原位角膜磨镶术(LASIK)后角膜后表面屈光力变化对角膜总屈光力的影响及其在术后屈光回退中所起的作用;分析角膜后表面屈光力变化的相关因素。 方法 对47例89眼施行LASIK,其中49眼高度近视,40眼中低度近视。术前与术后1个月,应用裂隙扫描角膜地形网检测角膜前后表面屈光力及隆起度。分析角膜后表面屈光力及角膜后表面隆起度变化的相关因素。 结果LASIK术后.角膜后表面屈光力与角膜后表面隆起度的改变均具有统计学意义(-6.64±0.23)D/(-7.19±O.28)D,P<0.05;(24.57±10.74)μm/(56.98±15.60)μm,P相似文献   

近视LASIK术后屈光回退眼和非回退眼角膜形态改变的差异

目的　比较近视LASIK术后屈光回退眼和非回退眼角膜形态改变的差异,并评价这种差异在近视回退中的可能作用机制。 方法　近视回退组 15眼;非回退组 21眼。运用OrbscanⅡ系统分别在LASIK术前,术后 1周、1个月和3个月测量两组的角膜前 /后表面曲率半径和中央角膜厚度。 结果　两组术后的中央角膜厚度值都随着随访时间而增长,术后 1周值显著低于术后 1个月(P=0 000)和术后 3个月值(P=0 000)。但两组术后角膜前后表面的变化过程不一致,回退组角膜后表面曲率半径保持相对稳定(P>0 05),而术后 3个月前表面曲率显著凸于 1周值 (P=0 002);非回退组角膜后表面随时间而变扁平(P<0 05),而前表面曲率半径保持相对稳定 (P>0 05)。 结论　LASIK术后全角膜向前膨隆可能是近视回退的主要因素。     

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。     

高度近视波前引导的LASIK后屈光回退角膜后表面形态变化

目的 观察高度近视波前引导的LASIK后屈光回退角膜后表面屈光力和后高度的变化及后表面高度最大值与角膜厚度最薄点的关系.方法 采用眼前节全景仪测量13眼高度近视渡前引导的LASIK后屈光回退患者的角膜后表面屈光力及后高度值,对这些参数进行统计学分析.结果 本次选取的46例(90眼)患者中术后12个月时发生屈光回退患者8例13眼.13眼术后12个月时角膜后表面屈光力及后高度值均比术前增加,差异均有统计学意义(均为P<0.05).角膜后表面顶点和最大高度的平均变化值分别为(3.21±1.62)μm和(2.30±1.11)μm,高于正常眼角膜后表面顶点和最大高度的平均变化值,但差异均无统计学意义(均为P>0.05).角膜后表面高度最大值与角膜厚度最薄点均不在同一位置.结论 重视高度近视渡前引导的LASIK后出现屈光回退时角膜后表面屈光力及后高度的变化,防止或及时发现术后圆锥角膜.     

SBK与LASIK治疗高度近视眼患者的临床对比研究

目的 比较前弹力层下准分子激光原位角膜磨镶术(sub-Bowman keratomileusis,SBK)和传统准分子激光原住角膜磨镶术(laser in situ keratomileusis,LASIK)治疗高度近视眼患者的有效性和安全性.方法 随机使用SBK和LASIK 2种方法治疗近视度数大于-6.00 D的近视眼患者95例(95眼),术中测量角膜基质床厚度及角膜瓣厚度并进行比较.术后1个月、3个月、6个月、12个月检查并记录裸眼视力、屈光状态、角膜情况等并进行比较.结果 SBK组角膜瓣平均厚度为(108.23 ±11.63)μm,LASIK组为(143.89±21.65)μm,2组比较差异有显著统计学意义(t=-13.321,P=0.000).术后1个月、3个月、6个月、12个月,裸眼视力≥1.0者SBK组分别占95.9%、93.9%、91.8%和91.8%,LASIK组分别占91.3%、93.5%、87.O%和84.8%;屈光度在±0.50 D之间者SBK组分别占69.4%、73.5%、79.6%和83.7%,LASIK组分别占63.O%、67.4%、69.6%和67.4%,差异均无统计学意义(X2=0.428、0.422、1.263、3.428,P=0.513、0.516、0.261、0.064).SBK组1例出现轻微角膜上皮下混浊,LASIK组2例出现屈光回退.SBK组泪膜破裂时间术后3个月恢复至术前水平,LASIK组6个月恢复至术前水平.SBK组角膜基质床厚度平均为(323.27±20.57)μm,LASIK组平均为(295.74±14.58)μm,2组比较差异有统计学意义(t=7.480,P=0.038).术后12个月时角膜后表面Diff值SBK组为(0.037±0.011)mm,LASIK组为(0.050±0.012)mm,2组比较差异无统计学意义(t=-5.242,P=0.390).结论 SBK组治疗高度近视的安全性和有效性与LASIK组相同,SBK组术后早期的裸眼视力及12个月时屈光状态优于LASIK组,而治疗后保留的角膜基质更多,干眼恢复更快,生物力学稳定性更好.     

准分子激光原位角膜磨镶术术后角膜后表面前凸和屈光力的变化

目的研究准分子激光原位角膜磨镶术(laser insitu keratomileusis,LASIK)术后角膜后表面前凸和屈光力的变化及影响二者变化的相关因素。方法对接受LASIK手术并有术后6个月随访记录、近视屈光度(等效球镜)为(-6.50±2.75)D的52例患者(76眼),于术前及术后第1个月、第2个月和第6个月分别行Orbscan-Ⅱ裂隙光扫描角膜地形图检查,测量角膜后表面前凸值、角膜后表面屈光力,观察其变化。用多元逐级回归法分析术前角膜最薄点厚度,以及眼内压、切削量与术后角膜后表面前凸的相关性。结果术后第1个月角膜后表面前凸值为(38.81±17.87)μm,术后第2个月为(35.61±13.60)μm,术后第6个月为(36.45±14.34)μm;3.0 mm直径角膜后表面屈光力均值术后第1个月为(-6.85±0.23)D,术后第2个月为(-6.83±0.28)D,术后第6个月为(-6.81±0.25)D;5.0 mm直径角膜后表面屈光力均值术后第1个月为(-6.34±0.24)D,术后第2个月为(-6.38±0.21)D,术后第6个月为(-6.39±0.25)D,上述观察值与术前比较差异有显著性(P<0.01),但术后第1个月同术后第2个月、第6个月比较差异无显著性。角膜后表面前凸值与角膜后表面屈光力线性相关(r=0.6,P<0.01)。多元逐级回归分析与术后角膜后表面前凸的变化有关系的变量为切削量(非标准系数B=0.405,P<0.01),角膜最薄点厚度(非标准系数B=-0.109,P<0.01),术前眼内压未进入最后回归方程。结论LASIK术后角膜后表面形态有显著性改变,角膜后表面呈锥形前凸,随术后时间延长角膜后表面形态趋于稳定;角膜厚度越薄、切削量越大则术后的角膜前凸值就越大。     

LASIK后角膜后表面形态的研究

目的：研究激光角膜原位磨镶术（LASIK）前后,角膜后表面屈光度及曲率半径的改变以及影响因素。方法：随机选择停戴隐形眼镜一月以上的中高度近视41眼进行LASIK治疗,依角膜光学区直径的不同,分3mm区及5mm区两组,应用Orbscan分别观察分析其术前及术后3天、3月角膜后表达屈光度和曲率半径。结果：各组术前与术后各期相比,角膜后表面屈光度和曲率半径的改变均有显著性意义（P＜0.05),角膜中央变化较周边明显（P＜0.05）,角膜3mm区术后3月与3天相比差异有显著性意义（P＜0.05),角膜后表面曲率半径的改变与患眼正常眼压无关,与 术后角膜厚度存在统计学相关性（r=-0.6,P＜0.05),厚度小于350μm时角膜后表面形态变化较厚度大于350μm时明显（P＜0.01)。结论：激光角膜原位磨镶术可引起角膜后表面屈光度增大,曲率半径减少,术后角膜厚度是主要影响因素,将术后角膜厚度大于350μm作为安全指标仍需作进一步的研究。     

美容性角膜覆盖术疗效观察

目的:评价美容性角膜覆盖术治疗角膜(角巩膜)葡萄肿的临床效果。方法:对22例角膜(角巩膜)葡萄肿患者进行了美容性角膜覆盖术治疗。术后对所有病例的临床效果进行了随访观察。结果:22例均治愈,残留部分视力的2例的视力术后有所改善(2例2眼从术前手动/眼前到术后指数/眼前)。22例无1例发生排斥,角膜覆盖片的颜色除第1例因缺乏经验术眼的颜色明显深于对侧正常或正常人群眼的颜色外,其它无1例褪色。结论:应用角膜覆盖术治疗角膜(角巩膜)葡萄肿22例(22眼)临床证明疗效确实、安全可靠。     

Lamellar corneal autograft for corneal perforation

BACKGROUND: Corneal perforation secondary to exteriorization of the haptic foot of the anterior chamber intraocular lens (IOL) is a rare complication in IOL surgery. CASE REPORT: A superior penetrating corneal defect developed in the right eye of a 74-year-old woman associated with exteriorization of the superior haptic of an anterior chamber IOL. METHODS: We describe the technique of repositioning and successful patching of the defect using a lamellar cornea-sclera rotational autograft. CONCLUSIONS: This technique is useful for small perforations when cornea donor tissue is not available.     

Influence of corneal astigmatism, corneal curvature and meridional differences on corneal hysteresis and corneal resistance factor

Background: This study investigated the influence of corneal astigmatism, corneal curvature and meridional differences on corneal hysteresis (CH) and the corneal resistance factor (CRF) in a group of normal Chinese persons. Methods: Ninety‐five participants were recruited and data from the eye with higher corneal astigmatism were analysed. The anterior corneal curvature was measured by corneal topography. The Goldmann‐correlated intraocular pressure (IOPg), corneal‐compensated intraocular pressure (IOPcc), CH and CRF at different meridians (default horizontal position, 10°, 20° and 30° along the superotemporal and inferonasal meridians) were obtained from an ocular response analyser. The corneal powers at these specific meridians also were calculated. Results: At the default position, the IOPg and CRF had weak correlations with corneal astigmatism, while the IOPcc and CH were not significantly correlated with corneal astigmatism. Both the IOPg and IOPcc were measured significantly higher at the default position. The CH and CRF were lower at the default position but the difference in the CRF from obliquity could not reach statistical significance. The CH was not significantly correlated with the corneal power at all meridians. The CRF correlated with the corneal power only at 30° superotemporal. Conclusion: Corneal astigmatism and head tilt did not have much effect on the measurement of CH and the CRF, both of which were lowest along the horizontal meridian. Clinically, the difference was small. The influence of corneal power on CH and the CRF was minimal.     

Anterior amorphous corneal opacity and corneal thinning

PurposeTo present the clinical features of four cases with bilateral anterior amorphous corneal opacity.MethodsA retrospective study in four patients with bilateral anterior amorphous corneal opacity was conducted. Examinations included visual acuity, keratometry, slit-lamp biomicroscopy, confocal microscopy, anterior segment optical coherence topography, and histology.ResultsThree female and one male patients (mean age, 52.3 ± 8.9 years) showed bilaterally oval, amorphous sheetlike corneal opacities with central depression and thinning. Superior limbal opacities were observed in two of these patients. The best-corrected visual acuity ranged from 20/50 to 20/400, and the mean of the keratometry was 39.81 ± 3.97 D (diopters). They had mild dry eyes. The anterior segment optical coherence topography demonstrated hyporeflective abnormalities in the anterior depressed stroma in these four patients. Confocal microscopy revealed large round cells at the epithelial layer in one patient, and amorphous opacities with some strand-shaped opacities in the anterior stroma in all four patients. The mean of the corneal endothelial cells density in the eight eyes was 1521 ± 402 cells/mm². Central corneal stromalysis occurred in three patients, and descemetocele developed in two eyes. One patient received penetrating keratoplasty and two underwent lamellar keratoplasty. The histology of the corneal specimen revealed edematous basal epithelial cells, focal collagen disorganization in the thin stroma, and wartlike excrescences in a thickened Descemet's membrane.ConclusionAnterior amorphous corneal opacity is a rare keratopathy and may be one kind of rare corneal degeneration or dystrophy. Corneal stromalysis may occur in hyporefrective amorphous opacities and progress to descemetocele.     

Macular corneal dystrophy and associated corneal thinning

Purpose

To identify the molecular genetic cause of macular corneal dystrophy (MCD) in four probands, and characterize phenotypic similarities between MCD and keratoconus.

Methods

We performed ophthalmological examination, Scheimpflug imaging (Pentacam, Oculus Inc.), histopathological examination of excised corneal buttons, and direct sequencing of the CHST6 coding region.

Results

Pentacam measurements were taken in six eyes of three probands. All showed diffuse corneal thinning with paracentral steepening of the anterior corneal surface that was graded as keratoconus by the integrated software, but without associated ectasia of the posterior corneal surface or regional thinning. Homozygous or compound heterozygous CHST6 mutations were identified in all cases, including two novel mutations, c.13C>T; p.(Arg5Cys) and c.289C>T; p.(Arg97Cys).

Discussion

Localized elevation of the anterior corneal curvature can occur in MCD in the absence of other features of keratoconus. The identification of a further two Czech probands with the compound allele c.[484C>G; 599T>G] supports the enrichment of this allele in the study population.     

角膜生物力学与光密度相关性研究

目的:探究角膜生物力学与角膜光密度的相关性。方法:前瞻性研究。选取2019-03/06在云南省第二人民医院拟行角膜屈光手术术前检查的患者为研究对象。采用Pentacam HR眼前节分析系统进行角膜光密度测量,以角膜顶点为中心,分为0~2mm、> 2~6mm、> 6~10mm直径范围3个区域,以角膜厚度分为前、中、后3层。选取Pentacam HR中角膜最薄点厚度值纳入研究。采用Corvis ST角膜生物力学分析仪测量,相关参数包括第一次压平的长度(AP1L)和速率(AP1V)、第2次压平的长度(AP2L)和速率(AP2V)、最大凹陷时顶点距离(PD)、曲率半径(HCR)和形变幅度(DA)。运用Pentacam&Corvis ST生物力学联合诊断平台软件综合分析检查结果,得出综合角膜生物力学参数(CBI)以及其它独立参数包括硬度参数(SP)、综合半径(IR)、Ambrosio相关厚度-水平方向(ARTh)、形变幅度比(DAR)。各区域光密度间差异采用方差分析,角膜生物力学各项参数与各区域光密度的相关性采用Pearson或Spearman分析。结果:不同直径范围、不同层面间光密度有差异(F=35.101,P<0.01;F=1002.897,P<0.01),CBI与独立生物力学参数中AP2L、AP2V、PD、DA、SP、IR、ARTh、DAR具有相关性(rs=-0.502,P<0.01;rs=-0.457,P=0.001;rs=0.428,P=0.002;rs=0.539,P<0.01;rs=-0.687,P<0.01;rs=0.716,P<0.01;rs=-0.728,P<0.01;rs=0.750,P<0.01)。CBI与角膜0~2mm范围内光密度呈正相关(r=0.343,P=0.015)。0~2mm范围内光密度与独立生物力学参数中AP2L、IR、ARTh、DAR有相关性(rs=-0.298,P=0.035;rs=0.368,P=0.009;rs=-0.419,P=0.002;rs=0.493,P<0.01)。结论:角膜中央区域光密度与角膜生物力学具有显著的关联,临床中可以通过光密度和生物力学对角膜健康状况进行综合评价。     

Evaluation of corneal hysteresis and corneal resistance factor after corneal cross-linking for keratoconus

Background  

To evaluate corneal hysteresis (CH) and corneal resistance factor (CRF) in keratoconic (KC) eyes before and after corneal collagen cross-linking (CXL). Furthermore, to determine potential correlations with a series of corneal and demographic factors.     

Response of corneal hysteresis and central corneal thickness following clear corneal cataract surgery

Purpose: To evaluate the effect of routine phacoemulsification in corneal viscoelastic properties determined by corneal hysteresis (CH) and central corneal thickness (CCT) and to explore the impact of phaco energy on the above parameters. Methods: Forty‐one eyes of 41 patients undergoing cataract surgery were enrolled in this prospective study. CH and CCT were measured preoperatively, 1 day and 1 week postoperatively. CCT measurement was performed using a non‐contact optical pachymeter followed by ocular response analyzer (ORA) examination. Intraoperatively ultrasound time, average phaco power and effective phaco time (EPT) were recorded. Results: Mean CH was 10.05 ± 1.86 mmHg preoperatively, 8.25 ± 1.85 mmHg 1 day and 9.12 ± 1.37 mmHg 1 week postoperatively (p < 0.001). The mean CCT was 534 ± 37.33 μm preoperatively, 592.22 ± 46.34 μm 1 day and 563.21 ± 49.84 μm 1 week postoperatively (p < 0.001). CCT and CH were statistically significantly correlated preoperatively (p = 0.01, r = 0.396). This correlation was not sustained on the first postoperative day (p = 0.094, r = 0.265) and was re‐established 1 week postoperatively (p = 0.002, r = 0.568). On the first postoperative day, the CCT increase was positively correlated with EPT (p = 0.009, r = 0.404), which was not found between CH change and EPT. Conclusion: Structural corneal alterations following cataract surgery resulted in a statistical change in CH and CCT. These two parameters responded in a different manner that clearly demarcates their different nature. On the first postoperative day, CCT increase was correlated at a statistically significant level with intraoperative EPT. This correlation was not found with CH reduction. Other factors, besides cornea oedema or phacoemulsification energy, could be responsible for this CH modification.