青光眼结构与功能损害的关系

青光眼视网膜神经节细胞及其轴突损害导致视网膜神经纤维层(RNFL)进行性萎缩,伴随出现视功能的损害.青光眼视野缺损典型表现为神经纤维束性视野缺损.一般认为先出现RNFL损害,再出现视野缺损,且视野缺损和RNFL损害的位置具有对应性.与HRT、GDx相比,OCT测量的RNFL厚度能更好地用于评价青光眼损害的结构与功能关系.青光眼结构损害和功能性改变之间的对应关系,对于青光眼的诊断、分期和视功能评估起着重要作用.本文就青光眼结构与功能损害关系的研究进展做一综述.     

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。     

使用变量角膜补偿的扫描激光偏振测定法和视网膜神经纤维层照相比较用于青光眼的检测

目的：在检测青光眼的对视网膜神经纤维层(RNFL)损伤时，比较使用变量角膜补偿的扫描激光偏振测定法(SLP)和标准的无赤光照相RNFL测定结果。     

HRT-Ⅱ在青光眼随访中的应用

目的:应用HRT-Ⅱ检测青光眼视神经乳头的形态改变及视网膜神经纤维的丢失,探讨HRT-Ⅱ在青光眼随访中的意义。方法:已确诊的青光眼患者50例63眼纳入本研究,利用HRT-Ⅱ每6～12mo观察视盘及视神经纤维的变化。结果:盘沿面积、盘沿体积、最大视杯深度、平均视网膜神经纤维层(RNFL)厚度、RNFL截面面积等视盘参数前后2次检查结果差异有显著性意义(P<0.05)。结论:HRT-Ⅱ能够快速、可重复性地测量视盘形态及视神经纤维层的改变,并且可以重复分析视盘参数的变化。     

绝对期青光眼视网膜神经纤维层活体影像学观察

尽管青光眼是多因素疾病，但最终均为视网膜神经节细胞的凋亡、变性和视神经的损害。Quigiey等的研究表明，青光眼患者的视网膜神经节细胞(RGC)丢失40％左右将出现临床可检测的视野损害。然而，临床绝对期青光眼视功能完全丧失时RGC是否完全丧失?本研究应用光学相干断层扫描仪(optic coherence tomograph，OCT)对绝对期青光眼的视网膜神经纤维层(retinal nerve fiber layer，RNFL)进行了定量观察，以间接了解RGC在绝对期青光眼患者的丢失情况。     

视网膜神经纤维层检测在诊断青光眼及近视合并青光眼中的价值

视网膜神经纤维层(retinal nerve fiber layer,RNFL)厚度的现代检测手段主要有海德堡视网膜断层扫描仪、光学相干断层成像术和偏振激光扫描仪等。检测RNFL厚度可以对青光眼的早期诊断提供依据。与青光眼一样,近视眼的RNFL也会变薄。所以近视合并青光眼时经常容易被误诊而延误青光眼的治疗时机。因此我们必须将单纯近视眼与近视合并青光眼区别开来。对RNFL的检测能否将单纯近视眼及近视合并青光眼区别开,国内外学者存在不同观点,现综述如下。     

视网膜厚度分析仪的眼科应用

视网膜厚度分析仪（RTA）是一种省时快速的检测视网膜厚度的方法，它对后极部视网膜厚度的检测有助于疾病的诊治。正常人群后极部视网膜厚度变异小，视觉最敏锐区黄斑位于此处，所以RTA广泛用于黄斑疾病的诊断及疗效监测；后极部视网膜神经纤维层又是青光眼早期损害部位之一，RTA可用于检测青光眼所致的视网膜神经纤维层的损害，有助于青光眼早期诊断。     

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.     

光学相干断层成像术与神经纤维层彩色立体照相在青光眼检查中应用比较

目的 :评价光学相干断层成像术 (OCT)测量视网膜神经纤维层 (RNEL)厚度在检测青光眼RNFL缺损中的作用。方法 :采用配对法 ,对 3 0例 43眼已确诊的原发性开角型青光眼均予OCT和RNFL彩色立体照相 ,对RNFL分别进行定量与定性的检查。结果 :OCT定量测量RNFL厚度在青光眼中的异常率为 81 40 % ,RNFL彩色立体照相的异常宰为 67 44 % ,经 χ2 检验 ,差异无显著性 (P >0 0 5 )。二种方法对RNFL缺损部位检出的一致率为 5 8 14 % ,κ值为 0 43。结论 :在青光眼RNFL病变的检测中 ,OCT对RNFL厚度的测量与RNFL彩色立体照相进行对照 ,具有较好的敏感性与一致性 ,可作为青光眼RNFL病变的有效检测手段。     

OCT检测原发性开角型青光眼视网膜神经纤维层厚度与视野平均缺损的相关性分析

目的探讨OCT检测原发性开角型青光眼(POAG)视网膜神经纤维层厚度(RNFL)与视野平均缺损(MD)的相关性。方法分别采用Ze iss-Humphrey,Stratus TM,Version3.0 OCT和OCTOPUS101全自动电脑视野分析仪对正常组25例(36只眼)和青光眼组52例(81只眼)进行检测,将各个青光眼组中心30°视野内全视网膜MD和OCT检测的RNFL厚度值进行比较,并做相关性分析。结果青光眼组MD均高于正常组(P<0.01),中期和晚期青光眼组RNFL值均低于正常组(P<0.05)。所有被检测者视野MD与RNFL厚度呈负的直线相关(相关系数为-0.626,P=0.000);青光眼组MD与RNFL厚度呈负的直线相关(相关系数为-0.615,P=0.000);正常组MD与RNFL厚度无直线相关性(相关系数为-0.022,P=0.910)。结论MD与RNFL厚度有很好的直线相关性,通过OCT对RNFL厚度的检测,有助于了解和监测POAG对RNFL的损伤,是一种很有价值和潜力的青光眼客观辅助诊断方法。     

Effects of inadequate anterior segment compensation on measurements with scanning laser polarimetry.

The effects of poor anterior segment compensation on scanning laser polarimetry measurements of the retinal nerve fiber layer (RNFL) were systematically explored. A prototype scanning laser polarimeter with an adjustable compensator to neutralize anterior segment birefringence was used. By systematically varying the magnitude and axis of anterior segment compensation in a healthy and a glaucomatous eye, marked changes were observed in RNFL appearance: the healthy eye could appear to have glaucomatous damage, whereas the glaucomatous eye could appear to have a thicker and healthier RNFL. Even small amounts of uncompensated corneal birefringence, which may occur in routine clinical use, resulted in apparent changes in RNFL morphology. Knowledge of this effect is important for clinicians when using scanning laser polarimetry in clinical practice.     

Progressive localized retinal nerve fiber layer loss following a retinal cotton wool spot

Localized retinal nerve fiber layer (RNFL) defects can be an early sign of glaucomatous damage. However, their presence is not pathognomonic of the disease. We report a case of a localized RNFL defect developing after a retinal cotton-wool spot in a patient with diabetes mellitus and systemic hypertension.     

Assessment of the retinal nerve fiber layer in clinical trials of glaucoma neuroprotection

Assessment of the retinal nerve fiber layer (RNFL) is appealing for use in clinical trials of glaucoma neuroprotection, as it is directly correlated with loss of ganglion cells, which is assumed to be a primary event in glaucomatous damage. Qualitative assessment of the RNFL includes ophthalmoscopy, color stereophotography, and red-free monochromatic photography. In contrast, confocal scanning laser ophthalmoscopy (CSLO), scanning laser polarimetry (GDx), optical coherence tomography (OCT), and retinal thickness analysis (RTA) objectively and quantitatively measure the RNFL thickness. These latter techniques are still in evolution. Continuing meticulous objective validation is necessary to assess the usefulness and limitations of these powerful tools. Nevertheless, there are excellent prospects for using longitudinal assessment of the RNFL in clinical trials of glaucoma neuroprotection.     

Wavelength-dependent change of retinal nerve fiber layer reflectance in glaucomatous retinas

Purpose. Retinal nerve fiber layer (RNFL) reflectance is often used in optical methods for RNFL assessment in clinical diagnosis of glaucoma, yet little is known about the reflectance property of the RNFL under the development of glaucoma. This study measured the changes in RNFL reflectance spectra that occurred in retinal nerve fiber bundles with different degrees of glaucomatous damage. Methods. A rat model of glaucoma with laser photocoagulation of trabecular meshwork was used. Reflectance of the RNFL in an isolated retina was measured at wavelengths of 400-830 nm. Cytostructural distribution of the bundles measured optically was evaluated by confocal imaging of immunohistochemistry staining of cytoskeletal components, F-actin, microtubules, and neurofilaments. RNFL reflectance spectra were studied in bundles with normal-looking appearance, early F-actin distortion, and apparent damage of all cytoskeletal components. Changes of RNFL reflectance spectra were studied at different radii (0.22, 0.33, and 0.44 mm) from the optic nerve head (ONH). Results. Bundles in 30 control retinas and 41 glaucomatous retinas were examined. In normal retinas, reflectance spectra were similar along the same bundles. In glaucomatous retinas, reflectance spectra changed along bundles with the spectra becoming flatter as bundle areas approached the ONH. Conclusions. Elevation of intraocular pressure (IOP) causes nonuniform changes in RNFL reflectance across wavelengths. Changes of reflectance spectra occur early in bundles near the ONH and prior to apparent cytoskeletal distortion. Using the ratio of RNFL reflectance measured at different wavelengths can provide early and sensitive detection of glaucomatous damage.     

Altered F-actin distribution in retinal nerve fiber layer of a rat model of glaucoma

Glaucoma damages the retinal nerve fiber layer (RNFL). The purpose of this study was to investigate the distribution in RNFL of axonal F-actin, a cytoskeletal component, under the development of glaucoma. Intraocular hypertension was induced in a rat model by translimbal laser photocoagulation of the trabecular meshwork. The retinas of control and treated eyes were obtained after different exposures to elevated IOP. Nerve fiber bundles were identified by fluorescent phalloidin staining of F-actin. Nuclei of cell bodies were identified by DAPI fluorescent counterstain. F-actin distribution in whole-mounted retinas was examined by confocal microscopy. En face and cross-sectional images of RNFL were collected around the optic nerve head (ONH). F-actin in normal RNFL was intensely and uniformly stained. In glaucomatous retina, F-actin staining was not uniform within bundles and total loss of F-actin staining was found in severely damaged areas. Altered F-actin often occurred near the ONH in bundles that appeared normal more peripherally. Both alteration and total loss of F-actin were found most often in dorsal retina. In normal RNFL, F-actin is rich and approximately uniformly distributed within nerve fiber bundles. Elevated IOP changes F-actin distribution in RNFL. Topographic features of F-actin alteration suggest that F-actin near the ONH is more sensitive to glaucomatous damage. The alteration pattern also suggests an ONH location for the glaucomatous insult in this rat model.     

Correlation between the retinal nerve fiber layer thickness and the pattern electroretinogram amplitude

OBJECTIVE: To establish a correlation between the retinal nerve fiber layer (RNFL) thickness measured by a scanning laser polarimeter (GDx) and the pattern electroretinogram (p-ERG) amplitudes in a heterogeneous population sample composed of normal subjects, ocular hypertensive and glaucomatous patients. METHODS: 112 subjects were considered: 40 glaucomatous patients, 39 ocular hypertensive and 33 normal subjects. All were examined with the GDx, and the RNFL thickness was measured. A transient p-ERG was then recorded. RESULTS: A statistically significant correlation was observed between the RNFL thickness and the p-ERG amplitudes (p < 0.001) by means of linear regression analysis. CONCLUSION: We observed a strict correlation between the measurements of the RNFL thickness obtained with the GDx and the amplitude of the p-ERG signal. These techniques represent additional objective tools to detect an early glaucomatous damage.     

Change in retinal nerve fiber layer thickness after laser in situ keratomileusis

PURPOSE: To determine the effect of laser in situ keratomileusis (LASIK) on retinal nerve fiber layer (RNFL) dropout. SETTING: Nevyas Eye Associates, Philadelphia, Pennsylvania, USA. METHODS: This prospective consecutive study comprised 120 eyes. The GDx((R)) nerve fiber analyzer (Laser Diagnostic Technologies, Inc.) was used to measure RNFL thickness, an early indicator of glaucomatous damage, preoperatively and 1 week to 4 months and 6 months postoperatively to determine whether any change in apparent RNFL thickness was due to corneal change or to actual RNFL damage and to determine whether apoptotic cascade caused ongoing RNFL dropout. Humphrey visual fields were done in eyes with an abnormal GDx (increase of 20 in GDx number). RESULTS: The GDx was normal in 89 eyes, including 6 eyes with tilted discs, an abnormal number, and a normal image and 15 eyes with a nonprogressive increase in the GDx number. Three eyes, normal at the interim, were abnormal at 6 months but had a normal visual field. Eleven eyes had a significant increase in the number at 6 months, including 1 eye that showed a possible glaucomatous visual field defect at 9 months and a normal visual field at 14 months. CONCLUSIONS: There was no evidence of RNFL thinning or glaucomatous damage. A new baseline GDx should be established post LASIK to correct for corneal change.     

Correlation between frequency doubling technology perimetry and scanning laser polarimetry in glaucoma suspects and glaucomatous eyes

The aim of this study was to determine the relationship between the frequency doubling technology (FDT) screening algorithm and parapapillary retinal nerve fiber layer (RNFL) thickness in the eyes of glaucoma suspects and patients with open angle glaucoma. FDT C20-1 screening program and a scanning laser polarimetry (SLP) system (GDx-NFA) was used to assess 53 glaucomatous eyes, 53 glaucoma suspects and 36 normal control eyes. In glaucomatous eyes, there were correlations between the FDT the screening algorithm and RNFL retardation values in several polarimetric indices, most significantly "inferior thickness" (r = -0.321, P = 0.029). In the eyes of glaucoma suspects, however, we observed no correlation between the FDT results and RNFL retardation values (r = 0.080, P > 0.05, "inferior thickness"). In glaucomatous eyes, the abnormal scores obtained with FDT screening program correlated negatively with RNFL retardation values, as measured by SLP. Despite poor correlation between the FDT abnormal score and RNFL retardation value in glaucoma suspects, detection of abnormality using the FDT screening protocol may aid in the assessment of early glaucomatous structural damage.     

Retinal nerve fiber layer measurements using laser scanning polarimetry in different stages of glaucomatous optic nerve damage

PURPOSE: To evaluate the diagnostic value of polarimetric measurements of the retinal nerve fiber layer (RNFL) thickness in different stages of glaucomatous optic nerve damage. METHODS: The study included 92 eyes of 46 controls (age 41.0+/-13.7 years) and a heterogeneous group of 232 eyes of 135 patients with different stages of glaucomatous optic nerve damage (age 54.0+/-10.2 years; 68 patients with primary open-angle glaucoma, 56 with normal-pressure glaucoma and 11 patients with secondary glaucoma due to primary dispersion syndrome or pseudoexfoliation syndrome). All control subjects and patients underwent complete ophthalmological examinations including scanning laser polarimetry of the RNFL using the GDx (Laser Diagnostic Technologies, San Diego, Calif.) and 15 degrees color stereo optic disc photographs. Only subjects and patients with disc area less than 3.4 mm(2) were included in the study. The total glaucoma group were divided into four subgroups according to the morphological criteria of the neuroretinal rim. RESULTS: The stage of morphological glaucomatous optic nerve damage was classified as follows: stage 0: n=92, stage 1: n=103, stage 2: n=65, stage 3: n=40, and stage 4: n=19. Differences in mean polarimetric retardation between controls and eyes with glaucoma were significant for all parameters except the variable symmetry. The most significant differences between controls and eyes with glaucomatous optic nerve damage were found with the "number" variable assigned by the neural network analysis ( P<0.001). With increasing stage of glaucomatous optic nerve damage, separation of the variable "the number" increased significantly. At a predetermined specificity of 90% the sensitivity of the groups with different stages of morphological glaucomatous optic nerve damage increased from 32% for stage 1 to 90% for stage 4. CONCLUSION: Polarimetric measurement of the RNFL thickness is significantly associated with morphological glaucomatous optic nerve damage. The fast performance, easy handling, and low cost of RNFL polarimetry mean that it can be included in the routine examination of glaucoma patients. Further study and refinement of this technique are indicated to improve its usefulness in both clinical diagnosis and in population-based case identification.     

Evaluation of the glaucomatous damage on retinal nerve fiber layer thickness measured by optical coherence tomography

PURPOSE: To evaluate the relationship between visual field and retinal nerve fiber layer (RNFL) thickness measured by optical coherent tomography (OCT) and to assess the diagnostic ability of OCT to distinguish between early glaucomatous or glaucoma-suspect eyes from normal eyes. DESIGN: Retrospective, non-randomized, cross-sectional study. METHODS: A total of 160 eyes of 120 normal Japanese adults, 23 eyes of 16 patients with ocular hypertension, 38 eyes of 35 glaucoma-suspect patients, and 237 glaucomatous eyes of 140 glaucoma patients were enrolled in the study. The glaucoma group included 89 early glaucomatous eyes. Thickness of the RNFL around the optic disk was determined with three 3.4-mm diameter circle OCT scans. Average and segmental RNFL thickness values were compared among all groups. The correlation between mean deviation and RNFL thickness in glaucomatous eyes was also analyzed. Receiver operating characteristic (ROC) curve area was calculated to discriminate normal eyes from early glaucomatous or glaucoma-suspect eyes. RESULTS: A significant relationship existed between the mean deviation and RNFL thickness in all parameters excluding the 3-o'clock area. The average RNFL thickness had the strongest correlation in all parameters (r = -0.729, P <.001). Retinal nerve fiber layer thickness at the 7-o'clock inferotemporal segment had the widest areas under the ROC curves in all parameters for early glaucomatous eyes (0.873). CONCLUSIONS: Measurement of RNFL thickness by OCT is useful in detecting early RNFL damage. Furthermore, OCT measurements of RNFL thickness may provide clinically relevant information in monitoring glaucomatous changes.