Relationship Between Corneal Hysteresis and Corneal Resistance Factor with Other Ocular Parameters

Abstract

Purpose: To evaluate the relationship between corneal hysteresis (CH) and corneal resistance factor (CRF) with age, central corneal thickness (CCT), corneal curvature (KM), corneal volume (CV), and refractive error in naïve eyes. Methods: 105 healthy subjects (58 male and 47 female) were included in this study. The ages ranged from 19 to 82 years (mean 43.1?±?15.4 years) and refraction between ?11?D and +6?D (mean ?0.79?±?2.95?D). CH and CRF obtained with the Ocular Response Analyzer (ORA) were correlated with age, refractive error, Goldmann Applanation Tonometry (GAT), and with CCT, KM, CV obtained with the Pentacam, and with Corneal-Compensated Intraocular Pressure (IOPcc) and Goldmann-correlated intraocular pressure measurement (IOPg) obtained with ORA. A multivariable mixed effect model was used to evaluate associations among these parameters. Results: CH ranged from 6.9 to 14.6?mmHg (mean 10.26?±?1.49?mmHg); CRF ranged from 5.8 to 17?mmHg (mean 10.38?±?1.64?mmHg). Multivariate analysis showed a statistically significant correlation between CH with CCT (p?<?0.001), and KM (p?<?0.001), and between CRF with CCT (p?<?0.001) and GAT (p?<?0.001). Conclusions: Our findings support the hypothesis that CH and CRF are related to the corneal shape and thickness, and show a decrease of CH with age.     

A case of congenital corneal anesthesia with hypopyon in china

 PURPOSE: To report a case of congenital corneal anesthesia (CCA) associated with hypopyon and tactile hypoesthesia. METHODS: Case report. RESULTS: A 3-year-old girl presented with redness and mild photophobia in the left eye accompanied by corneal ulcer, hypopyon, and corneal neovascularization. Corneal sensation was reduced bilaterally. She exhibited an absence of normal response to painful stimuli. She also had extensive ulceration of the lateral borders and tip of the tongue. The left corneal biopsy revealed negative cultures for bacteria and fungi. She was treated with human amniotic membrane transplantation in the left eye. The response to treatment was good. CONCLUSION: This is the first case of CCA reported in China. CCA is often misdiagnosed as infectious keratitis. Amniotic membrane transplantation is effective in repairing the severe corneal ulcer which may be associated with CCA.     

Biomechanics and structure of the cornea: implications and association with corneal disorders

Recent studies have shown that alterations in corneal biomechanical properties are associated with corneal pathologies, particularly corneal ectasia. Moreover, these alterations may have implications with regard to the outcomes of therapeutic modalities and corneal refractive surgeries. We address corneal anatomy and its relevance to corneal biomechanical characteristics, as well as ocular and systemic conditions associated with changes in corneal biomechanics.     

A new multiple noncontinuous puncture (pointage) technique for corneal tattooing

AIM:To assess the safety and cosmetic efficacy of a new multiple noncontinuous transepithelial puncture technique for tattooing a decompensated cornea.METHODS:It was anon-comparative clinical case series study.The study examines 33 eyes in 33 patients with total corneal opacity due to corneal decompensation, which developed following intraocular surgery.Corneal tattooing was performed using the multiple noncontinuous transepithelial puncture technique (i.e. pointage). The safety of this new surgical strategy was assessed by occurrence of adverse events for the follow-up period. The cosmetic efficacy was determined by the patient’s cosmetic satisfaction and independent observer’s opinion about patient appearance.RESULTS:Seven women and 26 men were included in the study. The mean age was 46.4±17.5y (range:7-67). In total, 30 of 33 patients (91%) reported cosmetic satisfaction within the follow-up period. Only 3 patients (9%) required additional tattooing due to cosmetic unsatisfaction. Cosmetic outcomes were analyzed and classified as excellent or good in 13 (39%) and 17 (52%) patients, respectively. No serious adverse events developed, except delayed epithelial healing in 3 cases.CONCLUSION:The cosmetic outcomes of the multiple noncontinuous transepithelial puncture technique for corneal tattooing were good. The safety of this method is higher than conventional procedures. This new procedure also provides improved cost-effectiveness and safety over current corneal tattooing techniques.     

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.     

过夜配戴角膜矫形镜(OK镜)后角膜曲率及厚度变化

目的了解过夜配戴角膜矫形镜(OK镜)后早期角膜曲率、角膜厚度及屈光度的变化.方法14个中低度近视患者(平均屈光度-3.89±1.26D)25眼,随机分成2组分别配戴Dk值不同的角膜矫形镜BE角膜矫形镜组(7人12眼,Dk≈140);E&E角膜矫形镜组(7人13眼,Dk＝58).采用夜戴方式,平均配戴时间10.76±1.27小时.用Orbscan角膜地形图系统检查配戴1晚后角膜曲率、角膜厚度的改变.同时记录裸眼视力及屈光度的改变.结果配戴1晚后所有患者的中央及周边的角膜均增厚(P＜0.05).Orbscan角膜地形图SimK值在垂直轴及水平轴均变平(垂直轴△SimK0.94±0.56D,P＜0.001;水平轴△SimK0.996=0.68D,P＜0.001).裸眼视力平均提高0.4±0.24(P＜0.001).屈光度平均减少-1.85±0.82D(P＜0.001).Dk值不同的2组之间中央及颞上方位点角膜增厚程度的差别有统计学意义.结论过夜配戴角膜矫形镜后减低近视屈光度的效果明显.初次过夜配戴角膜矫形镜可导致角膜厚度轻度增加.     

角膜基质透镜在角膜溃疡或穿孔修复中的应用

目的：研究由全飞秒激光SMILE手术所得的角膜基质透镜作为角膜移植材料治疗角膜溃疡的临床疗效。

方法：回顾性病例研究。收集本院2017-01/06角膜溃疡患者6例6眼,其中细菌性、真菌性、深层异物伴感染各1例1眼,角膜穿孔3例3眼。采用由全飞秒激光SMILE手术所得的角膜基质透镜作为角膜移植的材料进行修复手术,确保植片与角膜层间无空气间隙。术后随访1～6(平均3.71±1.56)mo,观察手术前后视力、角膜移植物存活情况及术后并发症发生情况等。

结果：所有患者均在控制感染下顺利完成手术,无术中并发症。术后所有角膜植片透明。末次随访时,患者最佳矫正视力(best corrected visual acuity,BCVA)较术前明显改善(0.48±0.12 vs 1.50±0.08),差异具有统计学意义(P<0.01)。

结论：来源于全飞秒激光屈光手术的角膜基质透镜用于角膜溃疡修复是安全有效的,但植片的远期疗效尚需进一步观察。     

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。     

Alcohol delamination of the corneal epithelium for recurrent corneal erosion syndrome

AIM: To evaluate the outcomes of alcohol delamination (ALD) of the corneal epithelium for the treatment of recurrent corneal erosion syndrome (RCES) and to implement a standardized treatment protocol for this condition utilizing evidence based practice and the findings of an internal audit. METHODS: A retrospective analysis of 42 eyes of 40 patients diagnosed with RCES who were treated with ALD between January 2006 and March 2016 was conducted. Patients had 20% alcohol applied to the cornea with the use of a well for 40s. Patients were reviewed one week later in the Outpatient Department. Outcome criteria were established based on standards from other studies in the medical literature. These included, a treatment success rate of at least 72% (defined as complete resolution of symptoms one month after treatment), a postoperative complication a rate of <5% (mainly infective keratitis, and subepithelial haze), and the absence of any detrimental effect on visual acuity in ≥95% of patients. RESULTS: The mean age at the time of ALD was 41.17±13.44y. Patients were followed for an average of 12.8±15.65mo. The majority were female (52.5%, n=21) and the majority of eyes treated with ALD were left eyes (62.9%, n=26). Trauma was the primary aetiology in our study population. Treatment was successful in 73.8% (n=31) of eyes and in 75% (n=30) of patients. Recurrence occurred in 26.2% of eyes at a mean of 10.41±12.63mo post treatment. CONCLUSION: ALD is an efficacious and cost-effective primary surgical intervention for RCES.     

Determination of corneal volume from anterior topography and topographic pachymetry: application to healthy and keratoconic eyes

Purpose: To describe a method to measure corneal volume from topography and pachymetry, and test its clinical use on a sample of healthy human subjects and a case of circumscribed posterior keratoconus. Methods: Corneal curvature (PCT 200^® corneal topography system; Optopol Technology SA, Zawiercie, Poland) and ultrasonic topographic pachometry on 25 points (Ophthasonic^® A‐Scan/Pachometer III; Teknar Inc., St Louis, MO, USA) were measured on each of 12 young healthy corneas and one cornea suffering from circumscribed posterior keratoconus. Topography and pachymetry data were used to calculate the coordinates for the corresponding points on the posterior surface of the cornea. TableCurve 3D software (Systat Software Inc., Chicago, IL, USA) was used to fit a surface to those points measured. Integration of the surface fitted to the data points, corresponding to the anterior and posterior corneal surfaces, was used to calculate the volume underneath each of them. Subtraction of volumes underneath anterior and posterior surfaces, taking into account an axial offset equal to the central corneal thickness, rendered corneal volume for the central 6 mm of the cornea. Results: Central corneal thickness ranged from 520 to 630 μm for the healthy corneas. Corneal volumes for this sample analyzed averaged 18.66 ± 1.15 mm³ (range 17.25–20.53 mm³). For the posterior keratoconic cornea, the affected area was located at about 1.5–2 mm from the corneal center on the 135° hemimeridian of the right eye, observed through topographic pachymetry. Calculated corneal volume for the central 6 mm was 16.072 mm³, noticeably lower than those found in the sample without pathology, but within the range for corneas presenting with keratoconus. Conclusions: Corneal volume is a useful parameter for characterising dystrophic corneas and can aid in the detection of rare anomalies which are hardly detected with corneal topography and/or central corneal thickness evaluation. A potentially useful measure of corneal volume can be calculated from anterior corneal topography and topographic pachymetry data. Values obtained are in good agreement with previous studies using corneal tomography techniques. The methodology has been shown to have potential for retrospective analysis of data, or where no access is available to tomographical techniques.     

使用猪角膜脱细胞基质的人板层角膜移植治疗真菌性角膜炎的临床观察

目的:观察猪角膜脱细胞基质构建的生物角膜支架用于人角膜板层移植术治疗药物难以控制的浅层真菌性角膜炎的效果.方法:对2015-06/2016-03我院收治的16例16眼真菌性角膜炎患者的临床资料进行回顾性分析.16例真菌性角膜炎进行猪角膜脱细胞基质移植,术后随访6mo.对患者术后视力、角膜植片情况、并发症及复发情况进行分析.结果:术后7~10d植片角膜上皮化.16例病例术后1mo角膜水肿,1mo后角膜水肿消失,角膜逐渐透明.术后1mo有2例出现术眼角膜上皮缺损,药物治疗均恢复.术后出现眼压高3例,给予降眼压治疗后眼压控制.随访期间未出现角膜溶解、感染复发、排斥现象.术后1、3、6mo视力分别为1.27±0.22,1.11±0.13,0.79±0.22,术后视力均较术前明显提高,术后1mo视力与术前相比无统计学差异(P=0.06),术后3、6mo视力与术前相比具有明显统计学差异(P=0.01、0.001);其中术后3mo与术后1mo视力相比无明显提高,结果无统计学差异(P=0.11),而术后6mo视力较术后1、3mo均有明显提高,结果具有显著统计学差异(P<0.001).结论:猪角膜脱细胞基质移植治疗真菌性角膜炎是安全、有效的方法.     

角膜中期保存过程中细胞凋亡的初步研究

目的 搪塞角膜中期保存过期中细胞凋亡现象,为改进角膜保存方法提供理论依据。方法采用Ｍ－Ｋ液、Ｍ－Ｋ＋ＥＧＦ液和Ｏｐｔｉｓｏｌ３种保存２液保存兔和人角膜,用光镜、电镜及Ｔ ＵＮＥＬ标记技术检测细胞凋亡发生情况。中保存液保持３、５、７天的兔角膜上皮、项质及内皮细胞层均可见细胞凋亡发生。结论细胞凋 角膜中期保存２过程中细胞失丧失的另外一种可能机制;细胞凋亡的发生对角膜中期保存效果存在一定的影响;表皮生长     

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.     

角膜中央周边厚度差与角膜生物力学的相关性

目的：探讨角膜中央与周边的厚度差异对角膜生物力学特性的影响。方法：回顾性系列病例研究。 收集2006年10月至2007年10月在邯郸眼科医院测量的健康人群336例（336眼）,来自邯郸眼科研究。 运用Orbscan-II测量角膜中央厚度（CCT）、角膜最薄点（TCP）以及3、4、5、6、7 mm处颞侧、上方、 鼻侧及下方的角膜厚度;通过计算3、4、5、6、7 mm区域角膜厚度与中央厚度的比值,得到反映角 膜中央与周边厚度差异的角膜厚度指数（CTI）。通过眼反应分析仪（ORA）测量角膜迟滞系数（CH）、 角膜阻力因子（CRF）;采用Pearson相关和Spearman相关分析CH、CRF与角膜厚度及年龄之间的相 关性;采用独立样本t检验分析7 mm CTI总体分布中两端的最大5%与最小5%两组之间CH和CRF 的差异。结果：研究对象4、5、6、7 mm角膜厚度与年龄均呈负相关（r=-0.15,P=0.003;r=-0.23, P<0.001;r=-0.33,P<0.001;r=-0.41,P<0.001）,且随直径增大相关性逐渐增加;角膜最薄点、CCT 及3 mm区域角膜厚度与年龄无相关性。5、6、7 mm CTI与年龄呈负相关（r=-0.18,P=0.001;r=-0.27, P<0.001;r=-0.27,P<0.001）,3、4 mm CTI与年龄无相关性。CH与年龄无明显相关性,CRF与年 龄呈负相关（r=-0.15,P=0.006）。CH与3、4、5、6 mm CTI呈负相关（r=-0.13,P=0.023;r=-0.14, P=0.010;r=-0.15,P=0.008;r=-0.13,P=0.019）,CRF与3、4、5、6 mm CTI也呈负相关（r=-0.21, P<0.001;r=-0.24,P<0.001;r=-0.26,P<0.001;r=-0.16,P=0.005）。7 mm CTI位于总体分布中两端的 最大5%与最小5%两组之间比较,CH和CRF差异有统计学意义（t=2.93,P=0.006;t=2.78,P=0.009）。 结论：随年龄增加,健康人群CCT变化不大而周边厚度明显下降。CCT与周边厚度差异较大的角膜 可能存在抵抗眼内压及外力作用能力下降的风险。     

过夜配戴角膜塑型镜后角膜曲率及角膜厚度的变化

目的:了解过夜配戴角膜塑型镜(Orthokeratology,简称OK镜)后早期角膜曲率、角膜厚度及屈光度的变化. 方法:14例25眼中低度近视患者(平均屈光度-3.89±1.26D),随机分成二组分别配戴Dk值不同的角膜塑型镜:BE角膜塑型镜组(7例12眼,Dk≈140);E&E角膜塑型镜组(7例13眼,Dk≈58).采用夜戴方式,平均配戴时间10.76±1.27小时.用Orbscan角膜地形图系统检查配戴一晚后角膜曲率、角膜厚度的改变.同时记录裸眼视力及屈光度的改变. 结果:配戴一晚后所有患者的中央及周边的角膜均增厚(P＜0.05).Orbscan角膜地形图Simk值在垂直轴及水平轴均变平(垂直轴△Simk:0.94±0.56D,P＜0.001;水平轴△Simk:0.996±0.68D,P＜0.001).裸眼视力平均提高0.4±0.24(P＜0.001).屈光度平均减少-1.85±0.82D(P＜0.001).Dk值不同的二组之间中央及颞上方位点角膜增厚程度的差别有统计学意义.结论:过夜配戴角膜塑型镜后减低近视屈光度的效果明显.初次过夜配戴角膜塑型镜可导致角膜厚度轻度增加.     

Macular corneal dystrophy: A review

Macular corneal dystrophy is a corneal stromal dystrophy which leads to progressive vision loss. Macular corneal dystrophy is an autosomal recessive condition in which there is abnormality of proteoglycan synthesis. Mutations in the carbohydrate sulfotransferase gene prevent normal sulfation of corneal keratan. Different immunophenotypes have been described depending on the presence of keratan sulfate in cornea and/or serum. The deposition of abnormal proteoglycans leads to loss of corneal transparency and decreased vision. Imaging techniques such as in vivo confocal microscopy and anterior segment ocular coherence tomography have helped enhance our understanding of the corneal ultrastructural changes in this condition. These imaging modalities provide additional information without the need for a tissue biopsy or excision. Traditionally, full-thickness penetrating keratoplasty to replace the opacified cornea has remained the standard of treatment to improve vision. However, newer surgical interventions such as deep anterior lamellar keratoplasty and phototherapeutic keratectomy have also been shown to play a role in the treatment. Disease recurrence remains a challenge and the reason for poor visual prognosis. Newer techniques such as gene-targeting therapies and enzyme replacement therapies are being studied for a potential permanent solution in macular corneal dystrophy. Recent research is directed toward development of genetically modified products to integrate into host corneal DNA and block the mutant genes and hence overcome the underlying pathophysiology. Enzyme replacement therapy is another intervention with potential to treat macular corneal dystrophy. Animal studies show clearance of accumulated keratan sulfate from the body tissues in the treatment of systemic mucopolysaccharidosis by long-term enzyme replacement therapy. Future research should be directed toward elucidation of the relationship between the mutated carbohydrate sulfotransferase gene, the mechanism of deposit formation, and the development of pharmaceutical agents based on gene therapy.     

去上皮快速角膜胶原交联术治疗进展期圆锥角膜

目的：研究去上皮快速角膜胶原交联术(CXL)治疗进展期圆锥角膜的疗效。

方法：回顾性研究。收集2020-04/2021-12就诊于宁夏回族自治区人民医院 宁夏眼科医院行去上皮快速CXL的进展期圆锥角膜患者32例43眼。于术前及术后1、3、6mo行裂隙灯、眼压、裸眼视力、矫正视力、角膜内皮镜、眼前节分析仪Pentacam和可视化角膜生物力学Corvis ST检查,记录手术前后角膜情况、裸眼视力(UCVA)、最佳矫正视力(BCVA)、角膜内皮数、角膜最大曲率(Kmax)、角膜厚度最薄点(TCT)、前后表面K1、K2值、矫正眼内压(bIOP)、第一次压平时间(A1T)、第一次压平长度(A1L)、第一次压平速度(A1V)、第二次压平时间(A2T)、第二次压平长度(A2L)、第二次压平速度(A2V))、最大形变幅度(HCDA)、最大形变曲率半径(HCR)、最大压陷时两峰间距(HCPD)、第1次压平时角膜硬度(SP-A1))值。

结果：术前、术后6mo UCVA(LogMAR)(1.06±0.49、0.78±0.39)和BCVA(LogMAR)(0.48±0.34、0.38±0.29)比较均有差异(P<0.05),角膜内皮细胞比较无差异(2917.39±288.38 vs 2959.19±336.27cells/mm²,P=0.477)。手术前后Kmax、TCT、前表面K1、K2值、后表面K1值比较均有差异(P<0.05),且均在术后1mo升高,术后3mo后恢复至术前水平,而后表面K2值比较无差异。手术前后A1T、HCPD、SP-A1比较差异均有统计学意义(P<0.05),A1L、A1V、A2T、A2L、A2V、HCDA、HCR、bIOP比较无差异(P>0.05)

结论：去上皮快速CXL在术后6mo内能够阻止进展期圆锥角膜进展并且具有一定的安全性。     

屈光性手术前ORBSCAN-Ⅱ角膜地形图40838例筛选分析

目的 对40838例屈光性手术前,进行 Orbscan-Ⅱ角膜地形图检查结果的筛选分析,为临床诊断角膜病及应用提供可靠依据.方法 通过Orbscan-Ⅱ角膜地形图检测,针对角膜地形,全角膜厚度,角膜前、后表面高度及角膜屈率的数据进行分析,筛选出821例(1368眼),由8种特殊原因进行的结果分析.结果 (1)进行选择性的治疗方式:后巩膜加固术,屈光性晶状体摘出联合人工晶状体置入术,有晶状体眼前房型人工晶状体植入矫治高度近视术.(2)避免一些手术禁忌症进行准分子激光屈光性手术:圆锥角膜、后圆椎角膜.(3)筛选450例1468项不正常的数据,不能进行任何治疗.结论 Orbscan-Ⅱ角膜地形图检查对手术方式的选择、术前手术方案的设计、术后疗效的评价、避免一些手术禁忌症的病例进行手术是至关重要的检查工具.