Five rules to evaluate the optic disc and retinal nerve fiber layer for glaucoma.

A systematic approach for the examination of the optic disc and retinal nerve fiber layer is described that will aid in the detection of glaucoma. This approach encompasses 5 rules: evaluation of optic disc size, neuroretinal rim size and shape, retinal nerve fiber layer, presence of parapapillary atrophy, and presence of retinal or optic disc hemorrhages. A systematic process enhances the ability to detect glaucomatous damage as well as the detection of progression, and facilitates appropriate management.     

Evaluation of the retinal nerve fiber layer in glaucoma

The health of the optic nerve in glaucoma can be evaluated by examination of the retinal nerve fiber layer with red free illumination. Retinal nerve fiber layer defects have been shown in some studies to precede enlargement of optic cupping and visual field defects in glaucoma patients. Detection of glaucomatous damage at an earlier stage in the disease may prevent subsequent visual field loss. Retinal nerve fiber layer evaluation may give important information in the management and treatment of glaucoma patients.     

Role of optic nerve imaging in glaucoma clinical practice and clinical trials

PURPOSE: To provide an update on the role of optic nerve and peripapillary retinal nerve fiber layer imaging in glaucoma clinical practice and clinical trials. DESIGN: Perspective. METHODS: Review of recent literature and authors' clinical and laboratory studies. RESULTS: Imaging technologies such as confocal scanning laser ophthalmoscopy, scanning laser polarimetry, and optical coherence tomography provide objective and quantitative measurements that are highly reproducible and show very good agreement with clinical estimates of optic nerve head structure and visual function. Structural assessments provided by imaging complement optic disk photography in clinical care and have the potential to identify relevant structural efficacy endpoints in glaucoma randomized clinical trials. As with other technologies, imaging may produce false identification of glaucoma and its progression; thus, clinicians should not make management decisions based solely on the results of one single test or technology. CONCLUSIONS: Although optic disk stereophotography represents the standard for documentation of glaucomatous structural damage in practice and research trials, advances in computerized imaging technology provide useful measures that assist the clinician in glaucoma diagnosis and monitoring and offer considerable opportunity for use as efficacy endpoints in clinical trials.     

High tech in the diagnosis of glaucoma

Scanning laser tomography (HRT, HRT II), scanning laser polarimetry (GDx nerve fibre analyser, GDx VCC), retinal thickness analyser (RTA) and optical coherence tomography (OCT, stratus OCT) provide objective measurements of the optic disc and the retinal nerve fibre layer suitable for the follow-up of glaucoma patients. Their ability to diagnose early glaucomatous damage is still limited but promising technical advances in this field can be expected in the future. For the moment, clinical examination and fundus photography still remain the gold standard for the assessment of glaucomatous optic disc and retinal nerve fibre layer damage.     

New technologies for diagnosing and monitoring glaucomatous optic neuropathy.

BACKGROUND: Recently, instruments have been developed to provide real-time, quantitative measurements of the optic disc and retinal nerve fiber layer (RNFL) for use in glaucoma management. Our objective is to (1) provide an overview of two of these instruments, the confocal scanning laser ophthalmoscope (Heidelberg Retina Tomograph, HRT) and scanning laser polarimeter (Nerve Fiber Analyzer, NFA) and (2) compare measurements obtained with these instruments to clinical features used in the diagnosis of glaucoma. METHODS: Twenty glaucoma patients, 4 normal subjects and 20 glaucoma subjects were included. All subjects had images obtained with the HRT and NFA, and RNFL and optic disc photography completed within 5 weeks of each other. The HRT results were compared with qualitative evaluation of stereophotographs of the optic disc, and NFA results were compared against a semi-quantitative RNFL photograph severity score. RESULTS: Twenty-five (57%) subjects had thinning of the neuroretinal rim identified by evaluation of stereoscopic optic disc photographs. Despite overlap, HRT measurements of rim volume, rim area, and rim/disc ratio were significantly smaller in eyes with evidence of rim thinning than in eyes with no evidence of rim thinning. Moderate to severe RNFL damage was detected by evaluation of photographs in 25 (57%) of subjects. NFA RNFL thickness measures were smaller in eyes with moderate to severe RNFL damage than in relatively healthy eyes. CONCLUSIONS: Previous studies have documented the reproducibility of these instruments and suggested analytic techniques for improving their ability to differentiate between normal and glaucoma eyes. Our results indicate that despite overlap in values, these instruments provide measurements that reflect clinically relevant features of the optic disc and RNFL. Whether these technologies can improve our ability to detect glaucomatous progression over time needs to be determined with well-designed longitudinal studies and comparison with established diagnostic techniques for evaluating glaucomatous optic neuropathy.     

Evaluating the optic disc and retinal nerve fiber layer in glaucoma. I: Clinical examination and photographic methods

Glaucoma is a leading cause of blindness worldwide and is characterized in part by specific changes in the optic disc and retinal nerve fiber layer. Currently, subjective clinical examination and fundus photography are the most common ways of detecting structural change in glaucoma and monitoring its progression. In the first part of this two-part article, the authors overview structural changes of the optic disc and retinal nerve fiber layer in glaucoma and describe and evaluate photographic methods for observing these changes. In the second part of this article (this issue), recent developments in computer-based optical imaging techniques that allow objective evaluation of the optic disc and retinal nerve fiber layer are described.     

Evaluating the Optic Disc and Retinal Nerve Fiber Layer in Glaucoma I: Clinical Examination and Photographic Methods

Glaucoma is a leading cause of blindness worldwide and is characterized in part by specific changes in the optic disc and retinal nerve fiber layer. Currently, subjective clinical examination and fundus photography are the most common ways of detecting structural change in glaucoma and monitoring its progression. In the first part of this two-part article, the authors overview structural changes of the optic disc and retinal nerve fiber layer in glaucoma and describe and evaluate photographic methods for observing these changes. In the second part of this article (this issue), recent developments in computer-based optical imaging techniques that allow objective evaluation of the optic disc and retinal nerve fiber layer are described     

New findings in the evaluation of the optic disc in glaucoma diagnosis

PURPOSE OF REVIEW: Ophthalmoscopical evaluation of the optic disc is a feasible and largely accessible method to diagnose glaucoma. Many qualitative parameters have been described in glaucomatous optic neuropathy. Considering individual variations in the details of topography or tissue components damaged by the glaucomatous process, however, adequate identification of glaucomatous optic disc signs requires training and experience. Without adequate guidelines of optic disc examination, the physician may miss important aspects that could lead to adequate diagnosis or identification of progression in a patient with established glaucoma. This paper presents a systematic approach for the examination of the optic disc and retinal nerve fiber layer to aid the detection of glaucoma. RECENT FINDINGS: Optic disc qualitative parameters are better than quantitative parameters in separating glaucomatous from normal eyes. The sequential evaluation of optic disc size, neuroretinal rim size and shape, retinal nerve fiber layer, presence of peripapillary atrophy, and presence of retinal or optic disc hemorrhages enhances the ability to detect glaucomatous damage and its progression. SUMMARY: Ophthalmologists should be familiar with glaucomatous optic disc signs that can be identified during clinical examination. A simple systematic approach may allow improved diagnosis and management of glaucoma.     

原发性开角型青光眼的中医分型与RNFL厚度改变及视野损害关系

目的:探讨原发性开角型青光眼(青风内障)中医辨证分型与视网膜神经纤维层厚度的改变及视野损害之间关系的临床研究。方法:对72例144眼原发性开角型青光眼患者,采用光学相干断层成像术对144眼作围绕视盘3.4mm的环形扫描,记录各个象限视网膜神经纤维层厚度,并采用进口Humphry视野分析仪作中30°全定量视野检测检查,同时根据中医理论对患者作中医辨证分型,观察二者之间的关系。结果:中医的证型与视网膜神经纤维层厚度改变类型有统计学意义,中医证型与视野损害的类型有统计学意义(P<0.05)。结论:视神经损害较严重多见于青风内障的虚证,视神经损害早期多见于实证,因此视神经损害的程度在一定的程度上给予中医辨证治疗一定的指导作用。     

Optical coherence tomography and scanning laser polarimetry in normal, ocular hypertensive, and glaucomatous eyes

PURPOSE: To evaluate the relationship between visual function and retinal nerve fiber layer measurements obtained with scanning laser polarimetry and optical coherence tomography in a masked, prospective trial. METHODS: Consecutive normal, ocular hypertensive, and glaucomatous subjects who met inclusion and exclusion criteria were evaluated. Complete ophthalmologic examination, disk photography, scanning laser polarimetry, optical coherence tomography, and automated achromatic perimetry were performed. RESULTS: Seventy-eight eyes of 78 patients (17 normal, 23 ocular hypertensive, and 38 glaucomatous) were enrolled (mean age, 56.8+/-11.5 years; range, 26 to 75 years). Eyes with glaucoma had significantly greater neural network scores on scanning laser polarimetry and lower maximum modulation, ellipse modulation, and mean retinal nerve fiber layer thickness measured with optical coherence tomography compared with normal and ocular hypertensive eyes, respectively (all P<.005). Significant associations were observed between neural network number (r = -.51, r = .03), maximum modulation (r = .39, r = -.32), ellipse modulation (r = .36, r = -.28), and optical coherence tomography-generated retinal nerve fiber layer thickness (r = .68, r = -.59) and visual field mean deviation and corrected pattern standard deviation, respectively. All scanning laser polarimetry parameters were significantly associated with optical coherence tomography-generated retinal nerve fiber layer thickness. CONCLUSION: Optical coherence tomography and scanning laser polarimetry were capable of differentiating glaucomatous from nonglaucomatous populations in this cohort; however considerable measurement overlap was observed among normal, ocular hypertensive, and glaucomatous eyes. Retinal nerve fiber layer structural measurements demonstrated good correlation with visual function, and retinal nerve fiber layer thickness by optical coherence tomography correlated with retardation measurements by scanning laser polarimetry.     

Optic disc area in different types of glaucoma

AIM: To evaluate the possible relationship of optic disc area with retina nerve fiber layer in different glaucoma subtypes. METHODS: One eye each was chosen from 45 patients with ocular hypertension, 45 patients with primary open angle glaucoma, 45 patients with pseudoexfoliation glaucoma and 45 healthy controls followed in our hospital. The records of the patients were reviewed retrospectively. Optic disc area and circumpapillary retina nerve fiber layer measurements were obtained using optical coherence tomography. Central corneal thickness was measured by ultrasound pachymetry. RESULTS: The median disc area in the patients with primary open angle glaucoma was significantly higher than the patients with ocular hypertension (2.19 vs 1.90 mm2, P=0.030). The median retina nerve fiber layer was thinner in the patients with primary open angle glaucoma and pseudoexfoliation glaucoma than the patients with ocular hypertension for superior, inferior and temporal quadrants. After adjustment for age, no difference in central corneal thickness was found between the groups. Greater disc area was associated with thicker retinal nerve fiber layer for superior, inferior and nasal quadrants in the patients with primary open angle glaucoma. There was no correlation between disc area and central corneal thickness measurements of the groups. CONCLUSION: Disc size affects the retinal nerve fiber layer thickness in eyes with primary open angle glaucoma and is a possible risk factor for glaucomatous optic nerve damage.     

眼底图像分析系统在原发性开角型青光眼早期诊断中的作用

眼底图像分析技术的迅速发展使视神经损害的直接定量检测成为可能,同时因其检测手段客观、结果可靠而日益受到重视.但由于临床医师对眼底图像分析技术如海德堡视网膜断层扫描、相干光断层扫描等在青光眼早期诊断中的意义仍存在认识上的分歧,因此有必要就此问题进行论述.有多数研究结果表明,现有的检测设备不仅在分辨率和重复性方面已经达到临床要求,而且能够较好地区分正常人和青光眼的眼底改变,但现阶段利用视神经结构定量指标来实现对青光眼的早期诊断,其敏感性和特异性尚不尽如人意.其原因是多方面的,如结构指标个体差异较大,缺乏完善的正常人数据库,缺乏达成共识的敏感而特异的诊断指标等.尽管如此,现有的研究趋势表明,利用图像分析技术测量青光眼性视神经损害已显示出令人鼓舞的临床应用前景,临床医师若能充分了解各种图像分析手段的优缺点,这些新的检测技术将成为早期诊断原发性开角型青光眼的有益补充手段.     

Linking structure and function in glaucoma

The glaucomas are a group of relatively common optic neuropathies, in which the pathological loss of retinal ganglion cells causes a progressive loss of sight and associated alterations in the retinal nerve fiber layer and optic nerve head. The diagnosis and management of glaucoma are often dependent on methods of clinical testing that either, 1) identify and quantify patterns of functional visual abnormality, or 2) quantify structural abnormality in the retinal nerve fiber layer, both of which are caused by loss of retinal ganglion cells. Although it is evident that the abnormalities in structure and function should be correlated, propositions to link losses in structure and function in glaucoma have been formulated only recently. The present report describes an attempt to build a model of these linking propositions using data from investigations of the relationships between losses of visual sensitivity and thinning of retinal nerve fiber layer over progressive stages of glaucoma severity. A foundation for the model was laid through the pointwise relationships between visual sensitivities (behavioral perimetry in monkeys with experimental glaucoma) and histological analyses of retinal ganglion cell densities in corresponding retinal locations. The subsequent blocks of the model were constructed from clinical studies of aging in normal human subjects and of clinical glaucoma in patients to provide a direct comparison of the results from standard clinical perimetry and optical coherence tomography. The final formulation is a nonlinear structure–function model that was evaluated by the accuracy and precision of translating visual sensitivities in a region of the visual field to produce a predicted thickness of the retinal nerve fiber layer in the peripapillary sector that corresponded to the region of reduced visual sensitivity. The model was tested on two independent patient populations, with results that confirmed the predictive relationship between the retinal nerve fiber layer thickness and visual sensitivities from clinical perimetry. Thus, the proposed model for linking structure and function in glaucoma has provided information that is important in understanding the results of standard clinical testing and the neuronal losses caused by glaucoma, which may have clinical application for inter-test comparisons of the stage of disease.     

OCT和SLP定量检测视网膜神经纤维层的研究进展

研究表明青光眼的视网膜神经纤维层(retinal nerve fiber layer,RNFL)损害早于视野改变。视网膜神经纤维层结构性损害的检测是青光眼早期诊断的重要手段。现代激光及计算机技术可以作为青光眼监测的有效方式。本文对OCT和SLP在RNFL定量检测方面的临床研究进展情况进行了综述。     

Imaging of the optic nerve and retinal nerve fiber layer: An essential part of glaucoma diagnosis and monitoring

Because glaucomatous damage is irreversible early detection of structural changes in the optic nerve head and retinal nerve fiber layer is imperative for timely diagnosis of glaucoma and monitoring of its progression. Significant improvements in ocular imaging have been made in recent years. Imaging techniques such as optical coherence tomography, scanning laser polarimetry and confocal scanning laser ophthalmoscopy rely on different properties of light to provide objective structural assessment of the optic nerve head, retinal nerve fiber layer and macula. In this review, we discuss the capabilities of these imaging modalities pertinent for diagnosis of glaucoma and detection of progressive glaucomatous damage and provide a review of the current knowledge on the clinical performance of these technologies.     

Measurement of peripapillary retinal nerve fiber layer volume in glaucoma

PURPOSE: To measure peripapillary retinal nerve fiber layer volume in normal subjects and patients with ocular hypertension, primary open-angle glaucoma, and low-tension glaucoma. METHODS: Sixty-five subjects were classified into four groups of normal subjects and subjects with ocular hypertension, primary open-angle glaucoma, and low-tension glaucoma on the basis of intraocular pressure measurements, visual field loss, and optic disk appearance. Groups were matched for sex, age, and optic disk area. Peripapillary retinal nerve fiber layer volume measurements were made with a modification of software version 1.11 of the Heidelberg Retina Tomograph confocal scanning laser ophthalmoscope. Retinal nerve fiber layer volume measurements were taken at 0.1-mm increments from the disk margin for a global 360-degree assessment and at four predefined segments using two different reference planes. Statistical analysis was carried out using analysis of variance with Bonferroni correction. RESULTS: Retinal nerve fiber layer volume measurements showed a gradation from normal to ocular hypertension and from ocular hypertension to glaucoma groups. Mean group measurements showed statistically significant differences (P <.05) in peripapillary retinal nerve fiber layer volume for most segmental measures between the groups. Measurements with the default reference plane in the 0.0-mm to 0.1-mm and 0.1-mm to 0.2-mm increments for the superotemporal segment showed the greatest differences between groups (P <.00005). CONCLUSION: Peripapillary retinal nerve fiber layer volume measurements differ between groups of normal subjects and patients with ocular hypertension, primary open-angle glaucoma, and low-tension glaucoma. This measure offers a further method of assessment of retinal nerve fiber layer in patients with glaucoma and glaucoma suspects.     

Peripapillary Retinal Nerve Fiber Layer Thickening Associated with Vitreopapillary Traction

Abstract

Purpose: To report two cases of retinal nerve fiber layer (RNFL) thickening as measured by Cirrus high-definition spectral-domain optical coherence tomography (OCT) associated with vitreopapillary traction. Methods: Consecutive peripapillary RNFL thickness assessments were performed using OCT in eyes with glaucoma and ocular hypertension. Results: OCT measurements revealed RNFL thickening when compared with the prior examination. A vitreopapillary traction to the thickened side of the RNFL was noted in a cross-sectional image of the optic nerve head obtained by OCT. Conclusion: Given that RNFL thickening can mask glaucomatous changes of the RNFL, caution is needed in glaucoma evaluation in eyes with vitreopapillary traction to the RNFL.     

Comparison of the Diagnostic Ability of Retinal Nerve Fiber Layer Thickness Measured using Time Domain and Spectral Domain Optical Coherence Tomography in Primary Open Angle Glaucoma

 Purpose: To evaluate and compare the diagnostic ability of retinal nerve fiber layer (RNFL) thickness measurements using time domain (Stratus) and spectral domain (Cirrus HD) optical coherence tomography (OCT) in preperimetric and early primary open angle glaucoma (POAG). Methods: A total 62 eyes of 62 normal subjects, 47 eyes of 47 early perimetric damage POAG patients and 30 eyes of 30 preperimetric glaucoma patients were chosen in the study. All the subjects underwent peripapillary RNFL thickness measurements using Stratus OCT and Cirrus HD-OCT on the same day by a single trained operator. The RNFL thickness measured by Stratus OCT and Cirrus HD-OCT was statistically compared using paired t-tests. The relationship between RNFL thickness measured by two OCT instruments was evaluated using Pearson’s correlation coefficient. Areas under the receiver operating characteristic curves (AROC) were calculated and compared. Results: RNFL thickness measured using Stratus OCT was generally thicker than that using Cirrus HD-OCT(P＜0.05). A highly significant correlation between the two OCT instruments measurements was found in four quadrants and average RNFL thickness measurements (P＜0.001). The average RNFL thickness of Cirrus HD-OCT had significantly (P = 0.006) higher diagnostic ability (AROC = 0.951) than that of Stratus OCT (AROC = 0.881) in preperimetric glaucoma. There were no significant differences between the AROCs for other RNFL thickness parameters from Cirrus HD-OCT and Stratus OCT in preperimetric and early glaucoma (P＞0.05). Conclusion: Significant differences and an excellent correlation were noted in terms of RNFL thickness measurements using Stratus OCT and Cirrus HD-OCT. Cirrus HD-OCT presented higher diagnostic ability for preperimetric glaucoma.     

Current imaging of the optic disk and retinal nerve fiber layer

The optic nerve head and the retinal nerve fiber layer (RNFL) are the sites of clinically detectable glaucomatous tissue damage. Photographic techniques are used to document the optic disk and the RNFL to monitor patients with suspected primary open-angle glaucoma or to follow-up patients already suffering from this disease. New techniques such as laser scanning tomography (LST), scanning laser polarimetry, and optical coherence tomography have been introduced to quantify structural alterations with the aim of early detection of optic nerve or RNFL damage prior to functional loss. These novel, additional diagnostic tools are currently being evaluated in clinical practice. While scanning laser polarimetry and optical coherence tomography are discussed elsewhere in this volume, articles on LST and conventional techniques are considered here. Imaging and computed data processing allow for three-dimensional in vivo measurements in the range of micrometers. With regard to the structure of the optic nerve head, this aspect in the evaluation of the optic disk can be based on quantitative topographic data. We expect "topometry" to become an important additional tool in the early diagnosis and follow-up of patients with glaucoma. However, computed parameter readings should always be evaluated in a clinical context. The goal is to improve, combine, and integrate all the different diagnostic approaches to improve patient care for the benefit of those suffering from glaucoma.     

Optic nerve head appearance in juvenile-onset chronic high-pressure glaucoma and normal-pressure glaucoma

OBJECTIVE: To evaluate the appearance of the optic nerve head in chronic high-pressure glaucoma and normal-pressure glaucoma. DESIGN: Clinic-based cross-sectional study. PARTICIPANTS: The study included 52 eyes with normal-pressure glaucoma and 28 eyes with juvenile-onset primary open-angle glaucoma that served as models for chronic high-pressure glaucoma. METHODS: Color stereo optic disc photographs and wide-angle retinal nerve fiber layer photographs were morphometrically examined. MAIN OUTCOME MEASURES: Localized retinal nerve fiber layer defects; parapapillary chorioretinal atrophy; disc hemorrhages; optic cup shape; retinal arteriole narrowing. RESULTS: Both study groups did not vary significantly in count of localized retinal nerve fiber layer defects, size of parapapillary atrophy, optic cup depth, steepness of disc cupping, rim/disc area ratio, diameter of retinal arterioles, and frequency and degree of focal retinal arteriole narrowing. In normal-pressure glaucoma versus juvenile open-angle glaucoma, localized retinal nerve fiber layer defects were significantly broader, disc hemorrhages were found significantly more often and were larger, and neuroretinal rim notches were present more frequently and were deeper. CONCLUSIONS: Chronic high-pressure glaucoma and normal-pressure glaucoma show morphologic similarities in the appearance of the optic nerve head. The lower frequencies of detected disc hemorrhages and rim notches in high-pressure glaucoma may be due to a smaller size of hemorrhages and localized retinal nerve fiber layer defects in high-pressure glaucoma. Both glaucoma types have morphologic features in common, suggesting that they may possibly belong to a spectrum of the same pathologic process.