角膜接触镜引起的角膜地形图的改变

应用电子计算机辅助的角膜地形图检测仪对２２眼戴角膜接触镜患者去除接触镜的１天、２周、３周分别进行角膜地形图检测，发现接触镜可引起角膜的ＳＲＩ，ＳＡＩ及形态、屈光的改变，且这种改变在去除接触镜后可以逐渐恢复正常。接触镜引起角膜地形图改变的分析的意义：鉴别临床前期的圆锥角膜，为角膜屈光手术提供真实的角膜形态和手术时间的选择。     

正常戴角膜接触镜患者的角膜地形图变化

通过对戴角膜接触镜患者停镜后进行定期角膜地形图观察，发现戴角膜接触镜可引起角膜变形，如中心区不规则散光、缺乏正常角膜的由中心向周围逐渐变扁平和丧失辐射性对称。停镜后角膜恢复正常形态的时间为2～8周，平均为4．07±1．76周。最长时间为12周。停镜2周左右角膜变化较明显。提示屈光性角膜手术前，对戴角膜接触镜患者要定期检查角膜地形图，直至角膜形态恢复正常，才可进行手术治疗。     

软性角膜接触镜对角膜地形图的影响

目的:探讨软性角膜接触镜对角膜地形图的影响。方法:利用角膜地形图ORBSCANⅡ检查戴软性角膜接触镜患者41例81眼取镜当天及2wk后的角膜中央厚度,角膜中心的屈光度,散光,角膜前、后表面高度和曲率半径的变化。用统计学配对t检验分析结果。结果:角膜中央厚度,角膜屈光度,散光两组数据之间有显著性差异;角膜前、后表面高度和曲率半径两组数据之间无显著性差异。结论:戴软性角膜接触镜会影响角膜形态,角膜中央厚度,角膜屈光度,散光在脱镜2wk的变化有显著性差异。这种改变可能主要与角膜的供氧得到改善,角膜基质水肿减轻有关。     

短期配戴角膜接触镜对角膜形态和厚度的影响

目的探讨短期配戴软性角膜接触镜对角膜形态和厚度的影响。方法对25名青壮年近视志愿者(50眼)(等值球镜:-0.50~-7.25 D)统一配戴软性角膜接触镜1个月,测定摘镜后1个月内不同时间的角膜形态和厚度变化,并与戴镜前比较。结果戴镜前和摘镜后不同时间,角膜地形图形态构成、角膜地形图散光轴向的变化构成及一些角膜前表面形态相关指数无显著性差异(P>0.05)。戴镜前与摘镜后角膜地形图形态完全一致者占62.5%,且均以不对称领结形为著;在摘镜后1 d、1周、2周,角膜地形图散光轴向变化在16°以上及31°以上均超过30%和20%,直到1个月后仍有24%的眼角膜地形图散光轴向的变化在16°以上;角膜厚度在摘镜后1 d、2周均明显高于戴镜前(P<0.05),直到1个月后才与戴镜前接近,且受日均戴镜时间的影响。结论短期配戴软性角膜接触镜对角膜形态和厚度的影响虽轻微但复杂,摘镜后1 d变化最显著,随着时间的延长逐渐恢复,直到1个月后才与戴镜前基本一致。日均戴镜时间对摘镜后角膜厚度变化有影响。     

配戴角膜接触镜后的角膜地形图分析

配戴角膜接触镜可引起角膜形态的改变,停戴接触镜后,角膜形态会逐渐恢复,其恢复时间还与配戴镜片的种类、配戴方式、配戴时间的长短、个体差异等均有相对的关系;配戴接触镜后还可以引起角膜厚度的改变.角膜地形图可以全面客观地评估接触镜配戴者的角膜形态改变,尤其是对接触镜配戴者进行屈光治疗时,可以适当掌握手术时机,同时,可用于鉴别早期圆锥角膜及指导接触镜的更佳验配.     

佩戴角膜接触镜后角膜变化的激光共焦显微镜观察

目的 应用激光共焦显微镜对长期佩戴角膜软性接触镜的患者活体角膜的组织结构变化进行观察.方法 用激光共焦显微镜对长期佩戴角膜软性接触镜的15例患者进行检查,并选择未戴角膜接触镜者11例进行对照,对两组结果进行比较.结果 1.佩戴角膜软性接触镜组与对照组相比,基底上皮细胞密度减少,为3705.00±447.62个/mm2(P＜0.05),角膜上皮层厚度变薄,为54.3±8.44μm(P＜0.05),并有部分剥脱.2.佩戴角膜软性接触镜组角膜内出现白色点状物,朗汉氏细胞数目多,成树枝状改变.3.角膜软性接触镜组与对照组相比神经纤维数量及密度无明显变化(P＞0.05),但曲折度增加,有分支出现(P＜0.05).结论 佩戴角膜软性接触镜,角膜组织可发生一系列改变,激光共焦显微镜与传统光学共焦显微镜相比,图象清晰,深度定位准确,在疾病的早期诊断、治疗和研究中将起重要作用.     

多焦软性角膜接触镜对周边屈光度及周边角膜屈光力的影响

目的：:观察配戴多焦软性角膜接触镜引起的周边屈光度及周边角膜屈光力的变化,研究二者之间的关系。方法：:自身对照研究。于2020年10月1─15日在温州医科大学收集成年近视受检者18例,在配戴单焦软性角膜接触镜（简称单焦软镜）和多焦软性角膜接触镜（简称多焦软镜）状态下分别采用红外自动验光仪和角膜地形图测量周边屈光度及周边...     

日戴与周戴软性接触镜近视患者角膜内皮细胞观察

目的观察日戴与周戴软性接触镜对角膜内皮细胞的影响，探讨戴镜安全性。方法应用非接触式角膜内皮显微镜观察日戴与周戴软性接触镜患者25人47眼及正常对照组24人48只眼的角膜内皮细胞。结果周戴软性接触镜组角膜内皮面积增大、细胞密度减少、六边形细胞百分率下降、变异系数增高；日戴软性接触镜组六边形细胞百分率下降、细胞变异系数增高。结论周戴软件接触镜对角膜内皮细胞密度和形态影响非常显著，日戴软性接触镜仅表现为角膜内皮形态异常。日戴软性接触镜比周戴软性接触镜安全。     

角膜接触镜对眼屈光的影响

目的探讨角膜接触锐对眼屈光的影响。方法利用SEED自动电脑验光仪观察测定160名（320眼）近视患者戴软性及送气性硬性角膜接触镜一年之中角膜屈率半径、角膜激光度及眼球镜度的变化。结果戴软性角膜接触镜一年后，眼屈光状态与裁镜前比较，无显著性变化。戴透气性硬性角膜接触镜一年后，眼屈光状态与戴镜前比较，有显著性变化；角膜曲车半径值平均增加0．12mm（P＜0．0005），角膜散光度平均降低0．65D（P＜0．0005），眼球镜度近视降低0．49D（0．005＜P＜0．01）。结论由此推断透气性硬性角膜接触锐对近视、散光有一定防治效果。     

配戴软性角膜接触镜对角膜中央厚度影响的临床研究

目的:探讨配戴软性角膜接触镜对中央角膜厚度的影响。方法:应用超声角膜测厚仪检测中央角膜厚度,在我院近视患者中随机抽取配戴软性角膜接触镜者及不戴镜者各100例200眼,做统计分析。再在近视患者中按戴镜时间<1a,1～3a,3～5a,5～7a,≥7a分组,每组随机抽取60例120眼,做统计分析。结果:配戴软性角膜接触镜者与不戴镜者的角膜厚度比较,差异有统计学意义(P<0.05)。戴镜时间<1a,1～3a,3～5a,5～7a者的角膜厚度比较,差异有统计学意义(P<0.05)。结论:配戴软性角膜接触镜者平均中央角膜厚度薄于不戴角膜接触镜者,并且配戴软性角膜接触镜的时间越长中央角膜厚度越薄。     

Viscoat黏弹剂联合软性角膜接触镜治疗角膜中央穿孔

目的 探讨Viscoat黏弹剂联合软性角膜接触镜治疗角膜中央穿孔的临床疗效.方法 收集我院眼科就诊的6例角膜中央穿孔患者的临床资料,角膜穿孔的直径均不超过2.0 mm,行角膜局部清创并在前房内注入Viscoat,然后予以配戴软性角膜接触镜,随访2～3个月,记录患者主观感觉、视力、裂隙灯检查、眼压、活体共聚焦显微镜、角膜内皮细胞计数等以判断疗效.结果 所有病例均达到治愈,治疗时长为1～2个月;最佳矫正视力提高至0.6～0.8,角膜内皮细胞计数为(3415.5±279.5)个·mm-2,角膜未留明显瘢痕,无严重并发症发生.结论 对于直径≤2.0 mm的外伤性角膜中央穿孔可通过应用Vis-coat黏弹剂联合软性角膜接触镜治疗,预后良好,并且减轻了患者的经济负担.     

多焦点角膜接触镜配戴后角膜屈光力的变化及其与眼轴增长的相关性

目的：观察儿童配戴多焦点角膜接触镜前后角膜屈光力分布情况,并分析戴镜后角膜屈光力与眼轴增长的相关性。方法：回顾性系列病例研究。收集2018年12月至2019年4月在温州医科大学附属眼视光医院杭州院区视光诊疗中心就诊行多焦点角膜接触镜验配并完成1年随访的8～14岁儿童20例 （40眼）。使用Medmont测量双眼戴镜前及戴镜30 min后角膜形态,手动收集角膜各位点上的切向屈 光力。收集角膜4个轴方向（鼻侧：N;颞侧：T;上方：S;下方：I）及中央处角膜屈光力。4个方位均为距离角膜顶点1～3.5 mm范围,以0.5 mm为间隔,记录为N/T/S/I（1/1.5/2/2.5/3/3.5）;同时收集戴镜后4个方位角膜最大屈光力值及角膜顶点处屈光力,并收集同样位置戴镜前角膜屈光力值,记录为N/T/S/I（max）。将各位点角膜屈光力与角膜顶点屈光力的差值定义为相对周边屈光力,角膜最大屈光力值与角膜顶点屈光力差值定义为相对最大屈光力。使用IOLMaster测量初始及戴镜1年后双眼眼轴长度。使用线性回归分析角膜相对最大屈光力值及其改变量与眼轴改变量的相关性。结果： 角膜周边各位点屈光力较中央屈光力弱。戴镜后水平方向上,除了N2.5、N3及N3.5之外的位点,其余位点相对周边屈光力显著增加;垂直方向上,除了S3、S3.5及I3.5之外的位点,其余位点相对周边屈光力显著增加。配戴多焦点角膜接触镜1年后,眼轴增长（0.28±0.21）mm。戴镜后角膜相对最大屈光力较戴镜前显著增加,其中初始年龄及等效球镜度（OR=0.393,F=3.447,P=0.042）、戴镜前后 Imax改变量（OR=0.157,F=7.057,P=0.011）及戴镜后相对Imax（OR=0.108,F=4.583,P=0.039）对眼轴增长有显著影响。结论：配戴多焦点角膜接触镜后,由相对周边正屈光力朝正屈光力改变。除年龄及等效球镜度外,戴镜后下方角膜相对最大屈光力及戴镜前后相对最大屈光力改变量对眼轴增长有显著影响,推测与戴镜后显著减少眼球相对周边远视离焦量相关。     

The cornea swells in the posterior direction under hydrogel contact lenses

Two mathematical models were developed to describe the topographical corneal swelling response to hydrogel contact lenses and the effect of these changes on refractive error. In one, corneal thickness changes resulted in deformation of the anterior corneal surface. In the other, the posterior surface only was deformed. Refractive error, corneal thickness and corneal shape were monitored in a sample of adapted contact lens wearers with one eye patched for 4 h while wearing a soft contact lens. The experimental data were most consistent with the model in which the posterior surface only was deformed.     

Rigid contact lens decentration: a risk factor for corneal warpage

Clinically significant contact lens induced corneal warpage is seen in a small proportion of soft and rigid contact lens wearers. Previous studies using the keratometer have found no correlation between the fit of the lens and the induced topographic changes. In this study, using computer-assisted topographic analysis, seven eyes (four patients) with rigid contact lens-induced corneal warpage were noted to have topographic abnormalities that correlated with the decentered resting position of the contact lens on the cornea. The warpage topography for each of these corneas was characterized by a relative flattening of the cornea underlying the resting position of the contact lens. Lenses that rode high, for example, produced flattening superiorly and resulted in a relatively steeper contour inferiorly that simulated the topography of early keratoconus patients who had not worn contact lenses. After discontinuing contact lenses the corneal topography returned to a normal pattern in five eyes. Two eyes retained asymmetry that is not characteristic of normal corneas. Up to 6 months was required for the corneas to return to a stable topography after contact lens wear was discontinued.     

Topographic changes in contact lens-induced corneal warpage

Twenty-one eyes of 12 patients with contact lens-induced corneal warpage were followed prospectively using computer-assisted topographic analysis. Sixteen eyes had worn rigid contact lenses (13 eyes, polymethylmethacrylate; three eyes, gas-permeable), and five eyes had worn soft contact lenses. Initial corneal topographic patterns were characterized by the presence of central irregular astigmatism, loss of radial symmetry, and frequent reversal of the normal topographic pattern of progressive flattening of corneal contour from the center to the periphery. A correlation was noted between the initial corneal topography and the resting position of the contact lens on the cornea for nine of the 16 eyes with rigid contact lenses. Initial topography for each of these corneas showed relative flattening of the corneal contour underlying the resting position of a decentered contact lens. Superior-riding lenses produced a topography that simulated early keratoconus. After cessation of contact lens wear, 16 of 21 eyes had a change in corneal shape to a topography that was consistent with a normal pattern. Five corneas stabilized with an abnormal topographic pattern. A much longer time without contact lenses than had been previously reported, up to 5 months, was required for a return of a stable corneal topography in eyes with contact lens-induced corneal warpage caused by rigid lenses.     

软性角膜接触镜在治疗角膜穿孔中的应用

目的评价软性角膜接触镜在治疗角膜穿孔中的效果。方法9例(9眼)新鲜角膜穿孔伴前房消失,其中角膜溃疡致穿孔7例,角膜穿孔伤2例。所有患眼均配戴软性角膜接触镜治疗。戴镜期间根据不同病例选择用药,接触镜每周消毒1次。结果所有患眼1~2 d内前房恢复,22~40 d角膜溃疡愈合,5例病灶见新生血管长入,1例角膜溃疡前房反复消失,后行穿透性角膜移植,2例角膜穿孔伤口对合整齐。结论软性角膜接触镜在治疗角膜小穿孔中是一种安全有效的辅助治疗方法。     

Contact lens assisted corneal cross linking in thin ectatic corneas – A review

Contact lens-assisted corneal cross-linking (CACXL) was introduced by Jacob et al. in 2012 for treating thin keratoconic corneas using riboflavin soaked soft contact lens to artificially increase the functional corneal thickness. It is advantageous over other thin corneal cross-linking techniques as it works independent of swelling properties of the cornea, is an epi-off technique and does not require additional time, additional expensive equipments or special solutions. The only additional requirement as compared to all other techniques is a UV barrier-free soft contact lens (Soflens™, B&L) which is easily available and inexpensive. Advantages include simplicity, easy adaptability, early visual rehabilitation, good visual outcomes, safety, and efficacy. Progression rates are acceptable and the need for re-treatment has been low. CACXL can help regularize corneal shape and may be used in isolation or synergistically with Intracorneal ring segments (ICRS) or Corneal allogenic intrastromal ring segments (CAIRS). It gives about 70% stiffening as compared to standard Dresden protocol CXL in less ideal porcine eye studies. Murine eye models that closely mimic thin corneas and show greater cross-linking effect as compared to porcine eyes may be a better model for evaluation of CACXL, however further studies are needed. Care should be taken in selecting the right kind of contact lens. Proper technique should be followed, especially by confirming thinnest functional pachymetry to be above 400 microns intra-operatively before application of UV-A. The sub-contact lens riboflavin film should be avoided as also an excessively thick supra-contact lens riboflavin film and too many re-applications.     

Posterior corneal curvature change and recovery after 6 months of overnight orthokeratology treatment

Purpose: To investigate the changes in, and recovery of, posterior corneal curvature after 6 months of overnight orthokeratology (ortho‐k). Methods: Twenty‐eight healthy young adults were recruited for a 6‐month period of ortho‐k treatment and data from their right eyes were analyzed. The mean ± standard deviation spherical equivalent refraction (SER) at baseline was ?2.95 ± 0.88 D. Posterior simulated keratometry (Sim K) readings were measured with a corneal topographer based on rotating Scheimpflug imaging. The three phases in the study were the 6‐month treatment period (Phase I); diurnal changes over a period of 8 h immediately after lens removal at the completion of the treatment period (Phase II); and a 2‐month recovery period after cessation of treatment (Phase III). Measurements were taken after lens wear overnight, and after 1 week, and 1, 2, 3 and 6 months of lens wear in Phase I. In Phase II, measurements were taken immediately, and then 2, 4 and 8 h after lens removal. In Phase III, corneal parameters were monitored 1 week, 2 weeks, 1 month and 2 months after cessation of ortho‐k treatment. Results: In Phase I, the posterior Sim K readings were significantly steepened after the first overnight lens wear. These significant changes were not found at other visits. In Phase II, the posterior Sim K readings were the steepest immediately after lens removal and significantly flattened 2 h after lens removal. In Phase III, all the posterior Sim K readings were similar to the baseline results. Conclusions: Steepening of the posterior cornea was only observed immediately after lens removal. It returns to its original shape within 2 h after cessation of lens wear. These changes appear to be in line with recent reports of the diurnal variation in the posterior corneal shape in non‐contact lens wearers. The reduction in myopia from ortho‐k treatment is therefore mainly due to a flattening of the anterior cornea.     

软性角膜接触镜治疗角膜溃疡穿孔的临床观察

目的:观察软性角膜接触镜治疗角膜溃疡穿孔的临床疗效。方法:对24例24眼角膜溃疡穿孔的患者采用配戴软性角膜接触镜治疗。其中细菌性14例14眼,病毒性8例8眼,真菌性2例2眼。戴镜期间根据不同病因选择联合用药,角膜镜配戴1wk清洗,3wk更换,角膜愈合后摘镜,随诊复查。结果:角膜溃疡穿孔患者24例24眼戴镜后1～2d前房均形成,5～10d后角膜上皮覆盖,角膜基质层纤维网状支架形成,20～32d角膜溃疡愈合,穿孔区密闭良好。患者视力有不同程度提高。结论:软性角膜接触镜是一种安全有效的角膜溃疡穿孔的辅助治疗方法。