GDx神经纤维厚度分析仪在正常中老年国人中的应用评价

目的 评价GDx神经纤维厚度分析仪在正常中老年国人中的检测意义。方法 采用GDx神经纤维厚度分析仪两种检测模式检测正常中老年国人的视网膜神经纤维层（RNFL）厚度。测量参数：TSNIT平均延迟、上方平均延迟、下方平均延迟、TSNIT标准差、神经纤维指数（NFI）。结果 VCC模式：5项参数分别为56.17±5.25,68.35±7.20,67.31±8.06,23.46±4.31,17.15±10.09。ECC模式：5项参数分别为54.15±5.12,67.28±8.33,67.91±8.70,25.80±3.72,18.88±10.51。两种模式参数检测结果均在正常范围,除下方平均延迟差异有统计学意义外其余4项参数之间的差异无统计学意义,所有检测参数指标与年龄均无统计学意义的相关性。结论 GDx神经纤维厚度分析仪对正常中老年国人RNFL厚度分布的测定结果符合生理解剖特点。VCC和ECC两种模式对检测正常中老年国人的RNFL厚度差异无统计学意义。     

青光眼视网膜神经纤维损害激光偏振光扫描测量的价值

目的:探讨青光眼的视网膜神经纤维层缺损特征,评价激光偏振光扫描测量仪(GDxVCC)在青光眼早期诊断方面的应用价值。方法:采用激光偏振光扫描测量仪(GDxVCC,美国)对60例110眼正常人及46例85眼青光眼患者视网膜后极部水平方向40°、垂直方向20°范围进行激光偏振光扫描测量视网膜神经纤维层厚度(RNFL),同时进行中央30°视网膜光阈值检查(Humphrey视野分析仪,Central30-2thresholdtest,美国),并对结果进行统计分析。结果:正常眼RNFL厚度与性别、眼别无关,而与年龄呈负相关;各期青光眼患者的RNFL均值显著低于正常对照组(年龄匹配,P<0.01);早期、进展期、晚期青光眼患者的RNFL厚度均值比较也有显著性差异(P<0.001)。GDxVCC检测RNFL厚度值与Humphrey视野检查指数平均缺损值(MD)具显著正相关性(r=0.795,P<0.001)。青光眼的视网膜神经纤维层图像可表现为局限性变薄或缺损(85.2%)、弥漫性变薄(6.6%)、弥漫性变薄并局限性缺损(8.2%),以鼻上方的局限性变薄或缺损最常见(56.7%)。有23.3%的早期青光眼患者视野检测正常而GDxVCC检测发现有不同程度的视网膜神经纤维层缺损。结论:GDxVCC能准确定量检测RNFL厚度值,视网膜神经纤维层的检测能比视野检测更早地发现青光眼的视神经的损害,因而可作为青光眼患者早期诊断的重要指标之一。随着青光眼患者病情的发展,RNFL厚度逐渐变薄,视野的平均缺损值逐渐增加。GDxVCC联合视野检查对于追踪青光眼患者的病情变化,确立靶眼压的水平,制定个性化的治疗方案有着重要的价值。     

薄角膜高眼压症患者的OCT、GDxVCC检测与分析

目的研究薄角膜高眼压症患者视盘周围视网膜神经纤维层(RNFL)光学相干光断层扫描(OCT)、偏振激光扫描仪联合个体化角膜补偿技术(GDxVCC)的参数特点。方法收集2010年9月至2011年9月在上海交通大学医学院附属仁济医院眼科门诊就诊的高眼压患者38例(38只眼)的病例资料做回顾性研究。把中央角膜厚度(CCT)高于中国人角膜厚度平均值(≥555μm)[1]共11只眼,分为组1。把CCT低于中国人角膜厚度平均值(<555μm)共27只眼,根据其CCT分为2组:组2(520μm≤CCT<555μm)和组3(CCT<520μm),比较分析3组眼压和视盘周围RNFL厚度等相关检查结果。结果 3组患者的OCT和GDxVCC检测参数包括Savg、Iavg、Avg.Thick、SA、IA、TSNIT、NFI比较,无显著性差异(P>0.05)。所有27例薄角膜高眼压患者(CCT<555μm)的视网膜神经纤维层缺损(RNFLD),以下方象限局限性缺损多见。盘沿面积(mm2)与RNFL平均厚度(μm)呈直线相关。结论 OCT和GDxVCC能对薄角膜高眼压患者视盘及RNFL做出定量测量和分析,在高眼压的诊断中有重要意义。而对于薄角膜高眼压患者,其角膜厚度水平与RNFLD程度无明显相关。     

糖尿病患者视网膜神经纤维层OCT测量的形态学观察

背景 传统的观点认为,糖尿病视网膜病变（DR）的主要病理机制是视网膜的微血管病变,但近年来发现糖尿病患者的视功能改变发生于DR的微血管病变发生之前,传统的观点无法解释糖尿病患者在出现可辨认的血管改变之前已有视功能改变的现象. 目的 应用频域光学相干断层扫描（OCT）观察无视网膜血管改变的糖尿病患者、非增生性糖尿病视网膜病变（NPDR）患者视网膜神经纤维层（RNFL）厚度的改变,分析糖尿病患者RNFL厚度与DR的关系. 方法 收集2012年10月至2013年9月于山西省眼科医院就诊且确诊的2型糖尿病患者56例60眼,按DR国际临床分型标准分为非糖尿病视网膜病变（NDR）组26例30眼和NPDR组（轻中度NPDR）30例30眼,同期纳入年龄和性别匹配的健康志愿者30人30眼作为对照.应用OCT对受试者行RNFL厚度测量,包括视盘周围及中心凹周围视网膜360°平均RNFL厚度及鼻上、颞上、颞侧、颞下、鼻下、鼻侧区域的RNFL厚度,比较各组患者RNFL厚度的变化. 结果 NDR组、NPDR组和正常对照组受试者视盘周围平均RNFL厚度分别为（97.46±8.65）、（100.69±16.35）和（109.22±8.69）μm,其中NDR组、NPDR组受试者视盘周围平均RNFL厚度值均低于正常对照组,差异均有统计学意义（P=0.001、0.006）;NDR组视盘周围各象限RNFL厚度均较正常对照组变薄,颞上、颞侧、颞下和鼻下象限RNFL厚度的差异均有统计学意义（P=0.001、0.001、0.001、0.010）;NPDR组视盘周围各象限RNFL厚度均较正常对照组变薄,其中颞上、鼻侧区域RNFL厚度的差异均有统计学意义（P=0.001、0.046）.NDR组、NPDR组和正常对照组平均黄斑区RNFL厚度分别为（33.47±3.39）、（36.81±3.21）、（38.18±2.16）μm,NDR组、NPDR组受试者黄斑区平均RNFL厚度值均低于正常对照组,其中NDR组与正常对照组比较差异有统计学意义（P=0.001）;NDR组黄斑区各区域RNFL厚度较正常     

垂体瘤患者视网膜神经纤维层厚度和视野变化参数相关性研究

目的 观察继发视功能损害的垂体瘤患者的视网膜神经纤维层厚度和视野变化参数之间的相关性,并比较偏振激光扫描仪(GDxVCC)和Octopus自动视野计在垂体瘤(PTT)患者检查中的敏感性及特异性.方法 对确诊为垂体瘤的70例患者(140只眼)分别行GDxVCC检查和Octopus自动视野计TOP程序视野(VF)检查.分析GDxVCC检查所得的双眼视网膜神经纤维层(RNFL)平均厚度、上方厚度、下方厚度与相对应的视野检查所得的双眼平均敏感度(Ms)、平均缺陷度(MD)与丢失方差(LV)的平方根及神经纤维指数(NFI)与平均缺陷度(MD)的5组参数,探讨这两种检查方法对垂体瘤视功能损害的敏感性及特异性并比较相应参数的相关性.结果 Octopus自动视野计检测PTT的敏感性为70.00%,特异性为34.00%;GDxVCC检测PTT的敏感性为72.22%,特异性为56.00%;两种方法联合检测PTT的敏感性为83.33%,特异性为58.00%(差异有统计学意义).双眼GDxVCC的RNFL平均厚度与VF检查的MS,上、下方的RNFL平均厚度分别与下、上方的MS比较均呈线性正相关(P＜0.01);左眼均较右眼明显.双眼GDxVCC的NFI与MD呈线性正相关(P＜0.01)双眼RNFL平均厚度与LV的平方根呈线性负相关(P＜0.01) GDxVCC联合视野检查有助于提高继发视功能损害的垂体瘤检测的敏感性及特异性.GDxVCC可以客观定量地反映视网膜神经纤维的结构性损害,并与视野的缺损有一定的相关性.     

中央角膜厚度与视网膜神经纤维层厚度关系在正常眼和高眼压患者之间的比较研究

目的通过角膜中央厚度分组,观察正常眼和高眼压患者的角膜厚度和视网膜神经纤维层（RNFL）厚度之间的关系,并通过相干光断层扫描成像（OCT）和偏振激光扫描仪联合个体化角膜补偿技术（GDx-VCC）检查高眼压患者是否存在RNFL的异常,并分析OCT和GDx-VCC测得的RNFL厚度之间的相关性。方法对眼压高于21 mm Hg（1 mm Hg=0.133 kPa）的患者测量其中央角膜厚度（CCT）,根据CCT值对眼压进行校正。OCTOPUS-101自动视野仪检查及视盘观察入选高眼压组患者180只眼,均予OCT、GDx-VCC测量视盘一周视网膜神经纤维层厚度,另设正常人180只眼作为对照,获得数据进行统计学分析。结果高眼压患者的平均CCT为（536.14±35.99）（433～609）μm,正常组患者的平均CCT为（516.68±38.27）（368～598）μm。根据平均中央角膜厚度555μm分组,组间平均视网膜神经纤维层厚度（Average RNFL）、上方（S）、下方（I）的RNFL厚度以及其它参数有显著性差异,高眼压组CCT≤555μm的患者平均视网膜神经纤维层厚度要低于CCT〉555μm的患者。结论高眼压患者RNFL厚度GDx-VCC与OCT的检测值低于正常人。高眼压组CCT与平均视网膜神经纤维层厚度正相关。GDx-VCC与OCT有着较好的一致性。     

DR早期视网膜神经纤维层和角膜神经的变化及其相关性

目的:观察无视网膜微血管病变的糖尿病患者的视网膜神经纤维层(RNFL)和角膜神经纤维(CNF)变化,以及两者变化的相关性.方法:收集40例40眼2型糖尿病患者,经散瞳眼底检查未发现糖尿病视网膜病变,均接受光学相干断层扫描(OCT)检查和活体角膜共聚焦显微镜(IVCM)检查.另收集年龄匹配的80例80眼健康正常眼为对照,分为40例40眼只行OCT检查的RNFL对照组和40例40眼只行IVCM检查的CNF对照组.利用OCT观察视乳头上方、下方、颞侧、鼻侧和平均RNFL厚度,用IVCM观察角膜上皮下角膜神经纤维长度和角膜神经密度.结果:糖尿病组的视乳头上方、颞侧、鼻侧及平均RNFL与对照组比较,差异无统计学意义(P>0.05),但视乳头下方RNFL糖尿病组比RNFL对照组减少,差异有统计学意义(P=0.003).糖尿病组的角膜神经纤维长度、角膜神经密度均比CNF对照组减少(P<0.01).糖尿病组中,平均RNFL与角膜神经纤维长度和角膜神经密度呈正相关(r=0.518,P<0.01;r=0.484,P=0.002),下方RNFL与角膜神经纤维长度和角膜神经密度呈正相关(r=0.607,P<0.01;r=0.573,P<0.01).结论:糖尿病患者在未发现糖尿病视网膜病变前同时存在视网膜神经纤维层和角膜神经的丢失,视网膜神经纤维层变薄主要表现在下方象限,视网膜神经纤维层的变薄与角膜神经的减少呈正相关.     

轻度认知障碍和阿尔茨海默病患者视网膜神经纤维层厚度的研究

目的 了解轻度认知障碍（MCI）和阿尔茨海默病（AD）患者视网膜神经纤维层（RNFL）厚度的变化。设计 病例-对照研究。研究对象 北京海淀区4个社区和大兴区榆垡镇3个自然村50岁以上（包括50岁）的居民3122人中,排除确诊为青光眼等影响RNFL厚度疾病的患者后,剩余资料完整者共2511人,其中MCI 47例、AD 10例、认知正常者2454例;根据病例组的分布特征在认知正常者中随机抽取性别及年龄与病例组相匹配的正常对照167例作为正常对照组。方法 用简易精神状态检查法（MMSE）初步测试受试者的认知功能,然后根据文盲组≤19分、小学组≤22分、中学及中学以上≤26分的分界标准,对MMSE异常人群再进一步进行日常生活能力量表（ADL）、临床痴呆评定量表（CDR）和Hachinski缺血指数量表评定,然后根据病史及神经心理量表评分筛出MCI及AD患者;用海德堡OCT仪检测所有受试者鼻侧、颞侧、上极及下极的视网膜神经纤维层（RNFL）厚度。对MCI组、AD组及正常对照组的RNFL厚度进行比较。主要指标 视网膜神经纤维层（RNFL）厚度。结果 MCI组及AD组与正常对照组相比,在颞侧、上极及平均RNFL厚度上均明显变薄,组间有显著性差异（P均＜0.05）;MCI组与AD组相比,AD组各象限RNFL厚度均有变薄的趋势,但两组仅在颞侧的RNFL厚度有显著性差异（P＜0.05）。结论 与认知功能正常者相比,MCI及AD患者RNFL厚度在颞侧和上极明显变薄,且AD患者较MCI患者颞侧的RNFL厚度亦明显变薄,因此RNFL厚度可作为监测认知功能障碍的客观指标,颞侧RNFL厚度变化可能早期反映病情的进展。 （眼科, 2014, 23： 231-234）     

糖耐量异常及2型糖尿病患者早期视网膜损伤的观察

目的 观察糖耐量异常（IGT）人群和已确诊2型糖尿病（DM）尚未进展至糖尿病视网膜病变（DR）人群的视觉功能的异常及视网膜神经纤维层（RNFL）厚度的变化,探讨糖代谢异常造成的视网膜损伤。方法 横断面研究。随机选取2012年6月至2013年6月间于沧州市中心医院就诊的有2型DM病史10~15年但尚未进展至DR的患者76例为2型DM组,同期、同院就诊的IGT病史3年以上尚未进展至DM的患者79例为IGT组,随机选取同龄健康体检者80例为对照组。所有受检者进行OCT、视觉对比敏感度（CS）、视力、眼底镜等检测,2型DM患者进行FFA检查。以上受检者均取左眼的OCT和CS测量值计入统计结果。采用方差分析的方法,比较2型DM组和IGT组的视盘周围RNFL厚度与对照组的差异,分不同的年龄段比较2型DM组、IGT组与对照组CS检测值的差异,并采用相关分析分析RNFL厚度和CS检测值的相关性。结果 2型DM组RNFL的厚度值全周为（98.3±10.3）μm、视盘上方象限（114.8±14.7）μm、下方象限（128.5±15.4）μm 和鼻侧（71.4±8.6）μm,明显低于对照组（P<0.05）,IGT组的RNFL的厚度与对照组比较无明显差异。2型DM组的CS检测值与对照组比较,40岁~年龄段在6、12、18 c/d频段有明显差异（P<0.01）,50岁～年龄段和60~70岁年龄段在3、6、12、18 c/d频段有明显差异（P<0.05）,IGT组40岁～年龄段在12、18 c/d频段有明显差异（P<0.05）,50岁～年龄段在6、12、18 c/d频段有明显差异（P<0.05）,60～70岁年龄段在6、12 c/d频段有明显差异（P<0.05）。CS在6 c/d频段的检测值与RNFL平均厚度相关性分析显示两者呈正相关（r=0.596,P<0.01）。结论 2型DM患者在视网膜尚未出现可视的微血管病变以前,已经存在RNFL变薄和CS代表的部分视功能的减低;CS等视功能的减低的出现可能早于RNFL变薄。     

应用GDx VCC检测原发性开角型青光眼视网膜神经纤维层

目的 采用GDx VCC检测青光眼和正常人视网膜神经纤维层厚度(retinal nerve fiber layer,RNFL),并进行对比分析.方法 选择正常人44人44眼,原发性开角型青光眼患者45例45眼行GDx VCC检查.将获取的参数(椭圆平均值、上方平均值、下方平均值、TSNIT标准差、眼间对称性、视神经纤维指征)进行分析.结果 所有参数在正常人组与青光眼组比较中均有统计学意义(P＜0.01).GDxVCC不同参数检测青光眼RNFL缺损敏感性为68.9%～82.2%,特异性84.1%～100.0%.其中下方平均值、视神经纤维指征ROC曲线下面积为0.959、0.964.结论 GDx VCC在RNFL检查中有较高的敏感性和特异性,可客观反应受检者的RNFL情况,对于青光眼的早期诊断有一定的临床价值.     

Scanning laser polarimetry with enhanced corneal compensation for detection of axonal loss in band atrophy of the optic nerve

PURPOSE: To compare the abilities of scanning laser polarimetry (SLP) with enhanced corneal compensation (ECC) and variable corneal compensation (VCC) modes for detection of retinal nerve fiber layer (RNFL) loss in eyes with band atrophy (BA) of the optic nerve. DESIGN: Cross-sectional study. METHODS: Thirty-seven eyes from 37 patients with BA and temporal visual field defect from chiasmal compression and 40 eyes from 40 healthy subjects were studied. Subjects underwent standard automated perimetry and RNFL measurements using an SLP device equipped with VCC and ECC. Receiver operating characteristic (ROC) curves were calculated for each parameter. Pearson correlation coefficients were obtained to evaluate the relationship between RNFL thickness parameters and severity of visual field loss, as assessed by the temporal mean defect. RESULTS: All RNFL thickness parameters were significantly lower in eyes with BA compared with normal eyes with both compensation modes. However, no statistically significant differences were observed in the areas under the ROC curves for the different parameters between GDx VCC and ECC (Carl Zeiss Meditec, Inc, Dublin, California, USA). Structure-function relationships also were similar for both compensation modes. CONCLUSIONS: No significant differences were found between the diagnostic accuracy of GDx ECC and that of VCC for detection of BA of the optic nerve. The use of GDx ECC does not seem to provide a better evaluation of RNFL loss on the temporal and nasal sectors of the peripapillary retina in subjects with BA of the optic nerve.     

Detection of glaucoma using scanning laser polarimetry with enhanced corneal compensation

PURPOSE: To evaluate and compare the diagnostic accuracies for glaucoma detection of scanning laser polarimetry (SLP) with enhanced corneal compensation (GDx ECC) and variable corneal compensation (GDx VCC; both by Carl Zeiss Meditec, Dublin, CA), according to different levels of disease severity and presence of atypical retardation patterns. METHODS: The study included 102 eyes of 68 patients with glaucoma and 94 eyes of 55 normal subjects. All patients underwent SLP imaging with ECC and VCC methods on the same day. Severity of disease was based on the AGIS (Advanced Glaucoma Intervention Study) visual field score. An ROC regression model was fitted to evaluate the influence of disease severity and atypical retardation patterns (typical scan score [TSS]) on the diagnostic performance of the SLP parameters for both methods. RESULTS: GDx ECC performed significantly better than GDx VCC in glaucoma detection in patients with more severe atypical retardation patterns. For average disease severity and arbitrarily chosen TSS values of 20, 50, 70, and 100, the ROC curve areas for GDx ECC were 0.910, 0.935, 0.948, and 0.964. Corresponding values for GDx VCC were 0.684, 0.850, 0.920, and 0.975. For lower values of TSS and lower AGIS scores, GDx ECC performed significantly better than GDx VCC. CONCLUSIONS: GDx ECC performed significantly better than VCC for diagnosing glaucoma in patients with more severe atypical patterns of retardation and at earlier stages of disease.     

Enhanced imaging algorithm for scanning laser polarimetry with variable corneal compensation

PURPOSE: To describe and investigate a method of improving assessment of retinal nerve fiber layer (RNFL) morphology with scanning laser polarimetry (SLP) with variable corneal compensation (VCC). METHODS: By neutralizing anterior segment birefringence with a variable compensator, the current VCC method allows direct measurement of RNFL retardation. In the new method, enhanced corneal compensation (ECC), the variable compensator was set to introduce a "bias" birefringence. This bias was removed mathematically for each individual pixel to produce the RNFL image. In 177 eyes of healthy subjects, patients with glaucoma, and subjects with ocular hypertension, retardation images were obtained with both VCC and ECC. RESULTS: In the tested eyes, images obtained with ECC showed the expected RNFL appearance better than those obtained with VCC. In addition, the typical scan score, which quantifies the amount of atypia, was higher with ECC than with VCC. The amount of residual anterior segment birefringence dropped significantly with ECC in the various groups. Measurements of peripapillary RNFL retardation showed reduced temporal and nasal values with ECC, whereas superior and inferior values were not significantly different between VCC and ECC. The dynamic range appeared to have increased with ECC. The accuracy of the TSNIT (temporal, superior, nasal, inferior, temporal) average and inferior average for detecting glaucoma was higher with ECC than with VCC. CONCLUSIONS: RNFL morphology may be better assessed with the presented ECC method than with standard VCC. ECC may be implemented in the current VCC systems by means of a software upgrade. It may enhance the clinical utility of the GDx VCC in glaucoma management.     

Diabetes-associated retinal nerve fiber damage evaluated with scanning laser polarimetry

PURPOSE: To evaluate retinal nerve fiber layer (RNFL) thickness in patients with diabetes mellitus compared with age-matched normal control subjects, to assess the correlation between the RNFL thickness and the severity of retinopathy, and to investigate whether diabetes mellitus is a potential source of abnormal results in glaucoma screening or evaluation with scanning laser polarimetry (SLP). DESIGN: Cross-sectional analysis of normal and diabetic eyes. METHODS: setting: Institutional clinical study. patients: One hundred twenty-eight subjects with type 2 diabetes mellitus and 50 age-matched normal control subjects without glaucoma or glaucoma-suspect. All patients underwent imaging with SLP and repeatable automated perimetry. Subjects with diabetes mellitus were classified into four stages on the basis of the severity of retinopathy that was assessed by dilated funduscopic examination, high-quality fundus color photography, and fluorescein angiography. MAIN OUTCOME MEASURES: The SLP (GDx VCC software, version 5.5.0) parameters. RESULTS: The RNFL thickness in patients with diabetes mellitus was reduced significantly compared with age-matched normal control eyes (P < .01). Moreover, all RNFL thickness parameters of the GDx VCC software decreased significantly as an exacerbation of diabetic retinopathy (P = .0019, P = .0045, P = .0010 for temporal-superior-nasal-inferior-temporal (TSNIT) average, superior average, inferior average, respectively). The nerve fiber indicator also increased significantly (P < .0001), despite an absence of glaucomatous optic nerve damages. CONCLUSION: The RNFL thickness in type 2 diabetes mellitus, which was measured by GDx VCC software, significantly decreased with the severity of diabetic retinopathy. The presence of diabetes mellitus can be a source of false-positive results and overestimation of glaucomatous optic neuropathy when eyes are screened with GDx VCC software.     

偏振激光扫描仪联合个体化角膜补偿技术对可疑青光眼的随访研究

目的 对临床可疑青光眼患者进行长期的偏振激光扫描仪联合个体化角膜补偿技术(scanning laser polarimetry with variable corneal compensation, GDx VCC)随访,分析GDx VCC对该类患者的诊断价值.方法 选取门诊可疑青光眼的眼底检查视乳头杯/盘比(C/D)≥0.4,或双眼不对称且C/D差值≥0.2,静态视野检查结果正常患者68例,随访前后均用GDx VCC检查(采用相同的角膜补偿值).如双眼C/D值相同,随机选取1眼,如C/D值不同,则选取C/D值大的1眼,对结果进行t检验统计学分析.结果 随访时间6～30个月,平均(12.5±7.0)个月,眼底C/D值为 0.57±0.17.随访前后GDx VCC 检查:椭圆平均值分别为50.33±7.72和49.66±8.12,上方平均值为58.72±13.56和58.18±12.01,下方平均值为60.71±11.31和59.13±11.95,神经纤维指数为30.85±19.62和33.03±21.22,差异无统计学意义,但从绝对数值上,椭圆平均值、上方平均值和下方平均值变小,神经纤维指数变大.其中7例(10.3%)诊断为青光眼, 21例(30.9%)排除青光眼,40例(58.8%)仍需进一步随访.结论 对临床怀疑青光眼的患者应长期进行随访,GDx VCC随访对青光眼的诊断有一定的价值.(中国眼耳鼻喉科杂志,2009,9:92-94)     

The relationship between optical coherence tomography and scanning laser polarimetry measurements in glaucoma

PURPOSE: To investigate the relationship between optical coherence tomography (OCT) and scanning laser polarimetry (SLP) in measuring peripapillary retinal nerve fiber layer (RNFL) thickness in glaucomatous eyes. METHODS: Fifty glaucomatous eyes were evaluated in this study. Evaluations were analyzed two ways. First, parameters of the Stratus OCT (average thickness, superior/inferior average) and GDx VCC (TSNIT average, nerve fiber indicator (NFI), superior/inferior average) were correlated using the Pearson's correlation coefficient (r). Secondly, comparison (r) of these parameters was completed using the mean deviation (MD) of visual field defect. RESULTS: The following parameters were found to be significantly correlated (P < 0.005). TSNIT average/average thickness (r = 0.673), NFI/average thickness (r = -0.742), superior average (r = 0.841), and inferior average (r = 0.736). In the correlation analysis using the severity of visual field defect, all these parameters had statistically meaningful correlations (P < 0.005). CONCLUSIONS: GDx VCC and Stratus OCT are highly correlated in glaucomatous eyes. Therefore, peripapillary RNFL thickness measured by Stratus OCT and GDx VCC may be equally helpful in the diagnosis of glaucoma.     

Relevance vector machine and support vector machine classifier analysis of scanning laser polarimetry retinal nerve fiber layer measurements

PURPOSE: To classify healthy and glaucomatous eyes using relevance vector machine (RVM) and support vector machine (SVM) learning classifiers trained on retinal nerve fiber layer (RNFL) thickness measurements obtained by scanning laser polarimetry (SLP). METHODS: Seventy-two eyes of 72 healthy control subjects (average age = 64.3 +/- 8.8 years, visual field mean deviation = -0.71 +/- 1.2 dB) and 92 eyes of 92 patients with glaucoma (average age = 66.9 +/- 8.9 years, visual field mean deviation = -5.32 +/- 4.0 dB) were imaged with SLP with variable corneal compensation (GDx VCC; Laser Diagnostic Technologies, San Diego, CA). RVM and SVM learning classifiers were trained and tested on SLP-determined RNFL thickness measurements from 14 standard parameters and 64 sectors (approximately 5.6 degrees each) obtained in the circumpapillary area under the instrument-defined measurement ellipse (total 78 parameters). Ten-fold cross-validation was used to train and test RVM and SVM classifiers on unique subsets of the full 164-eye data set and areas under the receiver operating characteristic (AUROC) curve for the classification of eyes in the test set were generated. AUROC curve results from RVM and SVM were compared to those for 14 SLP software-generated global and regional RNFL thickness parameters. Also reported was the AUROC curve for the GDx VCC software-generated nerve fiber indicator (NFI). RESULTS: The AUROC curves for RVM and SVM were 0.90 and 0.91, respectively, and increased to 0.93 and 0.94 when the training sets were optimized with sequential forward and backward selection (resulting in reduced dimensional data sets). AUROC curves for optimized RVM and SVM were significantly larger than those for all individual SLP parameters. The AUROC curve for the NFI was 0.87. CONCLUSIONS: Results from RVM and SVM trained on SLP RNFL thickness measurements are similar and provide accurate classification of glaucomatous and healthy eyes. RVM may be preferable to SVM, because it provides a Bayesian-derived probability of glaucoma as an output. These results suggest that these machine learning classifiers show good potential for glaucoma diagnosis.     

Structure-function relationship is stronger with enhanced corneal compensation than with variable corneal compensation in scanning laser polarimetry

PURPOSE: To compare the structure-function relationship between peripapillary retinal nerve fiber layer (RNFL) retardation, measured with scanning laser polarimetry (SLP) with both enhanced and variable corneal compensation (ECC [enhanced corneal compensation] and VCC [variable corneal compensation], respectively; features of the GDx Nerve Fiber Analyzer; Carl Zeiss Meditec, Inc., Dublin, CA), and visual field (VF) sensitivity, measured with standard automated perimetry (SAP) in normal and glaucomatous eyes and the effect of marked atypical birefringence patterns (ABPs) on this relationship. METHODS: Thirty-three healthy subjects, and 68 patients with primary open-angle glaucoma (POAG) took part in the study. ECC and VCC images were taken in one randomly selected eye of each subject. VF tests were also obtained in the same eyes. The structure-function relationship was assessed in six peripapillary sectors and their matching VF areas and was reassessed after eliminating eyes with marked ABPs. RESULTS: Correlations (Spearman's correlation coefficients, r(s)) in the structure-function relationship were generally stronger in images taken with ECC than in those taken with VCC. With ECC, the relationship was significantly more curvilinear when VF sensitivity was expressed in the standard decibel scale and more linear when VF sensitivity was expressed in an antilog scale than with VCC. When eyes with marked ABP images were removed from the analysis, the structure-function relationship with VCC improved, and no statistically significantly differences were found in the relationships between VCC and ECC. CONCLUSIONS: The structure-function relationship between RNFL retardation and SAP VF sensitivity was stronger in images obtained with the GDx ECC than with the GDx VCC (Carl Zeiss Meditec, Inc., Dublin, CA). ABPs, which appeared more markedly with VCC than with ECC, weakened the structure-function relationship.     

The effect of atypical birefringence patterns on glaucoma detection using scanning laser polarimetry with variable corneal compensation

PURPOSE: The purpose of this study was to investigate the effect of the presence of atypical birefringence patterns, as measured by the typical scan score (TSS), on the diagnostic accuracy of a scanning laser polarimeter (the GDx VCC; Carl Zeiss Meditec, Inc., Dublin, CA) assessed by receiver operating characteristic (ROC) curves for discriminating between glaucoma and healthy eyes. METHODS: Two hundred thirty-three glaucomatous eyes (repeatable abnormal visual fields by pattern standard deviation [PSD] and/or glaucoma hemifield test [GHT]) from 153 patients with glaucoma and 104 eyes from 71 healthy participants enrolled in the UCSD Diagnostic Innovations in Glaucoma Study (DIGS) were imaged using the GDx VCC. An ROC regression model was used to evaluate the influence of the covariates TSS; disease severity, defined as standard automated perimetry (SAP) mean deviation [MD]; and age in years on the diagnostic accuracy of the GDx parameters nerve fiber indicator [NFI], TSNIT (temporal, superior, nasal, inferior, temporal) average thickness, superior average thickness, inferior average thickness, and TSNIT standard deviation. Areas under the ROC curve were calculated for specific levels of the covariates according to the results provided by the model. RESULTS: TSS and SAP MD significantly affected the diagnostic accuracy of each investigated GDx VCC parameter. Low TSSs, indicating the presence of atypical scans, were associated with decreased accuracy. For NFI, ROC curve areas ranged from 0.749 (when TSS = 20) to 0.904 (when TSS = 100). A similar influence of TSS was found for other parameters. In addition, diagnostic accuracy increased with increasing disease severity. For instance, for NFI, ROC curve areas ranged from 0.853 (when SAP MD = -3) to 0.954 (when SAP MD = -15). CONCLUSIONS: The diagnostic accuracy of GDx VCC parameters is affected by disease severity and is adversely affected by the presence of atypical retardation patterns (i.e., decreasing TSS). GDx VCC scans with atypical scan patterns should be interpreted with caution when used in clinical practice.     

Comparison of the GDx VCC scanning laser polarimeter and the stratus optical coherence tomograph in the detection of band atrophy of the optic nerve

AIM: To compare the ability of scanning laser polarimeter (SLP) with variable corneal compensation (GDx VCC) and optical coherence tomograph (Stratus OCT) to discriminate between eyes with band atrophy (BA) of the optic nerve and healthy eyes. METHODS: The study included 37 eyes with BA and temporal visual field (VF) defects from chiasmal compression, and 29 normal eyes. Subjects underwent standard automated perimetry (SAP) and retinal nerve fibre layer (RNFL) scans using GDx VCC and Stratus OCT. The severity of the VF defects was evaluated by the temporal mean defect (TMD), calculated as the average of 22 values of the temporal total deviation plot on SAP. Receiver operating characteristic (ROC) curves were calculated. Pearson's correlation coefficients were used to evaluate the relationship between RNFL thickness parameters and the TMD. RESULTS: No significant difference was found between the ROC curves areas (AUCs) for the GDx VCC and Stratus OCT with regard to average RNFL thickness (0.98 and 0.99, respectively) and the superior (0.94; 0.95), inferior (0.96; 0.97), and nasal (0.92; 0.96) quadrants. However, the AUC in the temporal quadrant (0.77) was significantly smaller (P<0.001) with GDx VCC than with Stratus OCT (0.98). Lower TMD values were associated with smaller RNFL thickness in most parameters from both equipments. CONCLUSION: Adding VCC resulted in improved performance in SLP when evaluating eyes with BA, and both technologies are sensitive in detecting average, superior, inferior, and nasal quadrant RNFL loss. However, GDx VCC still poorly discriminates RNFL loss in the temporal quadrant when compared with Stratus OCT.