The effect of ageing on retinal nerve fibre layer thickness: an evaluation by scanning laser polarimetry with variable corneal compensation

PURPOSE: To evaluate whether a significant age-related thinning of the retinal nerve fibre layer (RNFL) is measurable by means of scanning laser polarimetry with variable corneal compensation (GDx-VCC) in a sample of healthy eyes. METHODS: A sample of 324 eyes of 324 healthy subjects (mean age 56 +/- 14 years, range 21-85 years) underwent a complete ophthalmic evaluation, standard automated perimetry and RNFL scan with the GDx-VCC. Temporal-superior-nasal-inferior-temporal (TSNIT), superior and inferior average (SA and IA) values provided on the printout were collected and their mean value averaged from all eyes and also after separating the eyes by gender and by age decades. The values of the three parameters were plotted against age and linear regression was calculated. RESULTS: Ageing is associated with a significant RNFL thinning (0.08 micro, 0.16 micro and 0.12 micro per year for TSNIT, SA and IA, respectively; p < 0.001). Analysis showed a similar association with age decade (p < 0.001 on anova). For the TSNIT average, a 9.5% thinning from baseline values was estimated for a 65-year lifespan. Corresponding values for SA and IA were 16.2% and 11.7%, respectively. CONCLUSIONS: Analysis by GDx-VCC confirmed previous reports about significant age-related RNFL thinning. However, a lower rate per year was found, probably because GDx-VCC measurements are much more reliable than those obtained with the previous generation of polarimeters.     

The retinal nerve fibre layer thickness in glaucomatous hydrophthalmic eyes assessed by scanning laser polarimetry with variable corneal compensation in comparison with age‐matched healthy children

Purpose: To compare the thickness of the retinal nerve fibre layer (RNFL) in hydrophthalmic glaucomatous eyes in children with age‐matched healthy controls using scanning laser polarimetry with variable corneal compensation (GDxVCC). Methods: Twenty hydrophthalmic eyes of 20 patients with the mean age of 10.64 ± 3.02 years being treated for congenital or infantile glaucoma were included in the analysis. Evaluation of RNFL thickness measured by GDxVCC in standard Temporal‐Superior‐Nasal‐Inferior‐Temporal (TSNIT) parameters was performed. The results were compared to TSNIT values of an age‐matched control group of 120 healthy children published recently as referential values. The correlation between horizontal corneal diameter and RNFL thickness in hydrophthalmic eyes was also investigated. Results: The mean ± SD values in TSNIT Average, Superior Average, Inferior Average and TSNIT SD in hydrophthalmic eyes were 52.3 ± 11.4, 59.7 ± 17.1, 62.0 ± 15.6 and 20.0 ± 7.8 μm, respectively. All these values were significantly lower compared to referential TSNIT parameters of age‐matched healthy eyes (p = 0.021, p = 0.001, p = 0.003 and p = 0.018, respectively). A substantial number of hydrophthalmic eyes laid below the level of 5% probability of normality in respective TSNIT parameters: 30% of the eyes in TSNIT average, 50% of the eyes in superior average, 30% of the eyes in inferior average and 45% of the eyes in TSNIT SD. No significant correlation between enlarged corneal diameter and RNFL thickness was found. Conclusions: The mean values of all standard TSNIT parameters assessed using GDxVCC in hydrophthalmic glaucomatous eyes in children were significantly lower in comparison with referential values of healthy age‐matched children.     

Specificity and sensitivity of glaucoma detection in the Japanese population using scanning laser polarimetry.

AIMS: To investigate the usefulness of the scanning laser polarimeter (GDx; GDx Nerve Fiber Analyzer) for glaucoma detection in the Japanese population, and to investigate the difference in the thickness of retinal nerve fibre layer (RNFL) between normal tension glaucoma (NTG) and primary open angle glaucoma (POAG). METHODS: 69 eyes of 69 normal subjects and 115 eyes of 115 chronic open angle glaucoma patients (60 NTG and 55 POAG patients) were studied. The thickness of RNFL was measured with GDx. An eye was diagnosed as glaucomatous, if at least one original GDx variable showed p <5%. The difference in thickness of RNFL between the NTG and POAG groups was then investigated. RESULTS: 46 normal eyes (66.7%) were diagnosed as not glaucomatous (no variables showing p <5%), and 93 glaucomatous eyes (46 NTG and 47 POAG eyes) (80.9%) were diagnosed as glaucomatous. Actual values of average thickness, ellipse average, superior average, and superior integral were significantly lower in the POAG group than those in the NTG group. CONCLUSIONS: New variables which elucidate focal RNFL defects or early changes are needed to improve the moderate detection ability found in this present study. The pattern of the change in RNFL may differ in NTG and POAG groups.     

Impact of diabetic retinopathy on quantitative retinal nerve fiber layer measurement and glaucoma screening

PURPOSE: To investigate the impact of diabetic retinopathy on quantitative retinal nerve fiber layer (RNFL) assessment and diagnostic power for glaucoma by scanning laser polarimetry (GDx-VCC) and optical coherence tomography (StratusOCT). METHODS: The individual RNFL parameters of GDx and OCT were obtained for 170 eyes (one eye from each of 170 subjects [45 healthy, 47 glaucoma, 40 diabetes, and 38 glaucoma with diabetes]) and were compared among the four groups. Diabetic eyes had mild to moderate nonproliferative diabetic retinopathy (NPDR) without maculopathy. In glaucomatous eyes with or without diabetes, the ability to discriminate glaucoma was assessed by the areas under the receiver operating characteristic curves (AUROCs) and the sensitivities at more than 80% and 90% of specificities for each technique. RESULTS: Using GDx-VCC, significant differences (P < 0.05) in RNFL measurement parameters were found for all comparisons except those between glaucomatous eyes with diabetes and without diabetes. StratusOCT parameters did not detect significant differences between age-matched healthy and diabetic eyes. Among the parameters included, the nerve fiber indicator (NFI) of GDx-VCC and the inferior quadrant thickness (IQT) of StratusOCT had the largest AUROCs and sensitivities at specificities greater than 80%: NFI (0.912, 86%) and IQT (0.902, 85%) in glaucomatous eyes with diabetes; NFI (0.935, 92%) and IQT (0.921, 91%) in simple glaucomatous eyes. CONCLUSIONS: Mild to moderate NPDR causes a quantitative discrepancy in RNFL measurements between GDx-VCC and StratusOCT in simple diabetic eyes. However, mild to moderate glaucomatous optic neuropathy can be highly discriminated by the two imaging devices in eyes with diabetic retinopathy.     

GDxVCC系统检测视网膜神经纤维层在青光眼早期诊断中的价值

目的 比较正常人和不同程度青光眼患者GDxVCC系统检测RNFL参数的不同,评价GDx各参数的敏感性、特异性,探讨GDxVCC系统检测视网膜神经纤维层在青光眼早期诊断中的价值.方法 对35例(35只眼)原发性开角型青光眼、33例(33只眼)慢性闭角型青光眼、27例(27只眼)急性闭角型青光眼以及年龄相匹配的36人(36只眼)正常人进行GDxVCC系统和静态视野检查.GDxVCC系统检查,视盘周围视网膜神经纤维层(retinal nerve fiber layer,RNFL)任一参数与系统内所附中国正常人数据库对比概率＜5%或NFI＞30或视网膜神经纤维标准偏差图上连续有10个超级像素概率＜5%定义为具有青光眼性视网膜神经纤维层结构损害,并判断为青光眼.结果 22只正常眼被判断为非青光眼(61.1%),82只青光眼被判断为青光眼(86.3%),RNFL参数椭圆平均值、上方平均值、下方平均值、TSNIT标准偏差、神经纤维指数,标准偏差图诊断青光眼的敏感性分别为48.4%、56.8%、48.4%、50.5%、62.1%,特异性分别为97.2%、100%、97.2%、94.4%、97.2%、61.1%.GDxVCC系统诊断早期、中期、晚期青光眼的敏感性分别为77.36%、95.83%、100%.结论 GDxVCC系统诊断早期青光眼的敏感性和特异性均高,而且RNFL参数中神经纤维指数的敏感性最高.

Abstract：

Objective To evaluate the usefulness of the scanning laser polarimeter with variable corneal compensation (GDxVCC) for glaucoma detection in a Chinese population,and to investigate the retinal nerve fiber layer (RNFL) thickness difference between normal subjects and glaucoma patients.Methods Thirty-six eyes of 36 normal subjects,33 eyes of 33 primary chronic angle-closure glaucoma patients,27 eyes of 27 primary acute angle-closure glaucoma and 35 eyes of 35 primary open-angle glaucoma patients were studied.The glaucoma patients were age-matched with the normal.The thickness of retinal nerve fiber layer was measured with GDxVCC.An eye was diagnosed as glaucoma,ifone of the parameters showed P＜0.05 on the results of the examination reports including four TSNIT parameters (the average of TSNIT,superior,inferior,and TSNIT Std.Dev.),nerve fiber indicator (NFI) ＞ 30,and at least 10 consecutive defects of superpels showed in deviation map (P ＜0.05).Results Of 22 normal eyes (61.1%) were diagnosed as non-glaucoma and 82 glaucomatous eyes (86.3%) were diagnosed as glaucoma by GDxVCC.Sensitivity of the average of TSNIT,superior,inferior,TSNIT Std.Dev.,NFI and the deviation map were 48.4%,56.8%,48.4%,50.5%,62.1% respectively and specificity were 97.2%,100%,97.2%,94.4%,97.2% and 61.1% respectively.Sensitivity of detection early,moderate and progression glaucoma by GDxVCC were 77.36%,95.83%,100% respectively.Conclusions GDxVCC is a valuable technology to detect retinal nerve fiber layer defect in early glaucoma.It is shown that the NFI has highest sensitivity.     

Discrimination between glaucomatous and nonglaucomatous eyes using quantitative imaging devices and subjective optic nerve head assessment

PURPOSE: To compare the diagnostic ability of the confocal scanning laser ophthalmoscope (HRT-II; Heidelberg Engineering, Heidelberg, Germany), scanning laser polarimeter (GDx-VCC; Carl Zeiss Meditec, Inc., Dublin, CA), and optical coherence tomographer (StratusOCT, Carl Zeiss Meditec, Inc.) with subjective assessment of optic nerve head (ONH) stereophotographs in discriminating glaucomatous from nonglaucomatous eyes. METHODS: Data from 79 glaucomatous and 149 normal eyes of 228 subjects were included in the analysis. Three independent graders evaluated ONH stereophotographs. Receiver operating characteristic curves were constructed for each technique and sensitivity was estimated at 80% of specificity. Comparisons of areas under these curves (aROC) and agreement (kappa) were determined between stereophoto grading and best parameter from each technique. RESULTS: Stereophotograph grading had the largest aROC and sensitivity (0.903, 77.22%) in comparison with the best parameter from each technique: HRT-II global cup-to-disc area ratio (0.861, 75.95%); GDx-VCC Nerve Fiber Indicator (NFI; 0.836, 68.35%); and StratusOCT retinal nerve fiber layer (RNFL) thickness (0.844, 69.62%), ONH vertical integrated rim area (VIRA; 0.854, 73.42%), and macular thickness (0.815, 67.09%). The kappa between photograph grading and imaging parameters was 0.71 for StratusOCT-VIRA, 0.57 for HRT-II cup-to-disc area ratio, 0.51 for GDX-VCC NFI, 0.33 for StratusOCT RNFL, and 0.28 for StratusOCT macular thickness. CONCLUSIONS: Similar diagnostic ability was found for all imaging techniques, but none demonstrated superiority to subjective assessment of the ONH. Agreement between disease classification with subjective assessment of ONH and imaging techniques was greater for techniques that evaluate ONH topography than with techniques that evaluate RNFL parameters. A combination of subjective ONH evaluation with RNFL parameters provides additive information, may have clinical impact, and deserves to be considered in the design of future studies comparing objective techniques with subjective evaluation by general eye care providers.     

Scanning laser polarimetry with variable corneal compensation and optical coherence tomography in tilted disk

PURPOSE: To determine whether scanning laser polarimetry with variable corneal compensation (GDx-VCC) or optical coherence tomography (OCT) is helpful for the analysis of the retinal nerve fiber layer (RNFL) thickness in glaucoma subjects with tilted disk. DESIGN: Retrospective case-control study. METHODS: We included 21 glaucomatous eyes with tilted disk and 35 glaucomatous eyes without tilted disk. Peripapillary RNFL thickness measurement by GDx-VCC and OCT, and also visual field testing with a Humphrey Field Analyzer program 30-2 (HFA) were performed in all subjects. RESULTS: In the group without tilted disk, the RNFL thickness values obtained with GDx-VCC and OCT analysis had a good correlation with mean deviation (MD), and clearly showed stage-dependent reduction. Conversely, in the group with tilted disk, a discrepancy in the RNFL measurement between GDx-VCC and OCT was observed. The correlation of RNFL measurement to the visual field was further examined at each hemifield (superior and inferior). In the group without tilted disk, the measurements of both instruments at each hemifield were in good correlation with the mean pattern deviation values. However, in the group with tilted disk, the GDx-VCC derived values did not correlate with the visual field defect in both hemifields, whereas OCT was in good association with both mean pattern deviation values. Infrared images acquired with a wavelength of nearly 780 nm revealed a high reflex from the sclera in the tilted disk. CONCLUSIONS: Our study has suggested that RNFL analysis by OCT is more suitable for the glaucoma assessment in the tilted disk compared with GDx-VCC.     

Atypical pattern of retardation on GDx-VCC and its effect on retinal nerve fibre layer evaluation in glaucomatous eyes

PURPOSE: To assess the effect of atypical pattern of retardation (APR) on retinal nerve fibre layer (RNFL) measurements made by scanning laser polarimetry (SLP) with variable corneal compensation (GDx-VCC) in glaucomatous eyes. METHODS: One eye each of 30 glaucomatous patients (average mean deviation (MD): -6.4+/-4.8) with APR on GDx-VCC retardation map were selected. In total, 34 glaucomatous, age- and severity-matched eyes (average MD: -7.0+/-5.3) and 36 age-matched healthy subjects, both with a normal pattern of retardation (NPR) represented control groups. APR on retardation maps was characterized by alternating peripapillary circumferential bands of low and high retardation, or high retardation areas arranged in a spokelike pattern, or high retardation nasal and temporal splotchy areas. Typical scan score (TSS) was extracted for each included eye. GDx-VCC parameters (mean+/-SD) in the two groups of glaucomatous eyes were compared with healthy eyes' corresponding values (Mann-Whitney U-test). Areas under receiver operating characteristic (AUROC) curves were generated to assess the APR effect on the parameters' diagnostic ability. RESULTS: All parameters discriminated adequately between healthy and glaucomatous eyes with NPR (AUROCs > or =0.9 for nine parameters). On the contrary, considering healthy and glaucomatous eyes with APR, four thickness parameters could not separate the two groups and AUROCs > or =0.85 appeared only for Inferior and Superior Ratio, NFI, Max Modulation. CONCLUSION: APR may void the effect of custom compensation and provide spurious RNFL thickness measurements. When a printout of glaucomatous eyes with APR is evaluated, it is proper to rely on ratios, modulation parameters, and NFI, since the diagnostic ability of thickness parameters is significantly reduced.     

Visual field defects and normal nerve fiber layer: may they coexist in primary open-angle glaucoma?

The retinal nerve fiber layer (RNFL) is the anatomical structure most sensitive to glaucoma injury. Before a functional loss such as a visual field defect is displayed, a large number of nerve fibers can be damaged. However, there are glaucoma patients in which an apparently normal RNFL coexists with evident visual field defects. A total of 54 eyes affected with primary open-angle glaucoma were studied. Visual field was examined with the Humphrey Field Analyzer (Zeiss) using program 30-2. The Nerve Fiber Analyzer II (Laser Diagnostic Technologies) was used to study the RNFL of these patients. Mean deviation of the visual field ranged from 6 to 31 dB in all eyes that were examined. The average thickness of the RNFL ranged from 20 to 90 microm. According to our previous experience 75 microm was fixed as the cutoff between normal and pathological values of RNFL thickness. We identified 5 eyes with a RNFL thickness over 75 microm and a visual field with a mean deviation over 6 dB; 9% of the studied eyes were found to have a visual field defect with no changes in RNFL. We conclude that not all subjects have the same number of fibers at birth and that it is therefore possible to underestimate the RNFL changes. Our study illustrates that the concept of normal and altered has to be considered as a relative one for all the aspects characterizing the glaucomatous disease.     

视网膜神经纤维层定量测定在青光眼方面的应用

青光眼的主要病理过程是视网膜节细胞轴突（即视神经纤维）的丢失，故测量视网膜神经纤维层（ｒｅｔｉｎａｌｎｅｒｖｅｆｉｂｅｒｌａｙｅｒ，ＲＮＦＬ）来确定轴突丢失的程度在青光眼的早期诊断和治疗上具有非常重要的意义。近年来，计算机图像分析技术应用于眼科，它能对ＲＮＦＬ作出客观的量化检测。该文综述有关文献，就ＲＮＦＬ定量测定方法的原理，以及它们在青光眼ＲＮＦＬ损害检测方面的应用情况作一介绍。     

Fourier analysis of scanning laser polarimetry measurements with variable corneal compensation in glaucoma

PURPOSE: To apply Fourier analysis to the retinal nerve fiber layer (RNFL) thickness measurements obtained with scanning laser polarimetry (SLP), by using variable corneal compensation, and to evaluate the ability of this method to discriminate glaucomatous from normal eyes. METHODS: The study included one eye each of 55 patients with glaucoma and 52 healthy subjects. RNFL thickness measurements were obtained with a modified commercial scanning laser polarimeter (GDx Nerve Fiber Analyzer; Laser Diagnostic Technologies, Inc., San Diego, CA) so that corneal birefringence could be corrected on a subject-specific variable basis. The shape of the RNFL thickness double-hump pattern was analyzed by Fourier analysis of polarimetry data. Fourier coefficients and GDx parameters were compared between the two groups. A linear discriminant function was developed to identify and combine the most useful Fourier coefficients to separate the two groups. Receiver operating characteristic (ROC) curves were obtained for each measurement, and sensitivity values (at fixed specificities) were calculated. RESULTS: The Fourier-based linear discriminant function (LDF Fourier) resulted in a sensitivity of 84% for a specificity set at 92%. For similar specificity, the GDx software-provided parameters had sensitivities ranging from 24% to 69%. The area under ROC curve for the LDF Fourier was 0.949, significantly larger than the ROC curve area for the single best GDx software-provided parameter, superior average (0.870). CONCLUSIONS: The combination of Fourier RNFL thickness measures in an LDF, obtained using SLP with variable corneal compensation, improved the ability to discriminate glaucomatous from healthy eyes, compared with the GDx software-provided parameters.     

Circadian fluctuation of mean ocular perfusion pressure is a consistent risk factor for normal-tension glaucoma

PURPOSE: To investigate systemic and ocular hemodynamic risk factors for glaucomatous damage in eyes with normal tension glaucoma (NTG). METHODS: Each patient with diagnosed NTG underwent 24-hour monitoring of intraocular pressure (IOP) and blood pressure (BP), scanning laser polarimetry (GDx-VCC), and a Humphrey visual field (HVF) examination. Multivariate regression models were used to evaluate potential risk factors: age, spherical equivalent, central corneal thickness (CCT), mean/peak in-hospital IOP, circadian IOP fluctuation, average mean arterial pressure (MAP), circadian MAP fluctuation, and circadian fluctuation of mean ocular perfusion pressure (MOPP). Functional outcome variables for glaucomatous damage were mean deviation (MD), pattern SD (PSD), and Advanced Glaucoma Intervention Study (AGIS) score. Anatomic outcome variables were TSNIT (temporal, superior, nasal, inferior, and temporal) average, superior average, inferior average, and nerve fiber indicator (NFI) on GDx-VCC. RESULTS: One hundred thirteen eyes of 113 patients met the inclusion criteria. In the multivariate regression models, larger circadian MOPP fluctuation was significantly associated with decreased MD, increased PSD, and increased AGIS score among functional outcome variables and with reduced TSNIT average, reduced inferior average, and increased NFI among anatomic outcome variables. Larger MAP fluctuation was associated with decreased MD, increased PSD, reduced TSNIT average, reduced inferior average, and increased NFI. CCT was not associated with any outcome variable. CONCLUSIONS: Of the functional and anatomic outcome variables, circadian MOPP fluctuation was the most consistent clinical risk factor for glaucoma severity in eyes with NTG. This finding may suggest an etiology of NTG as a chronic ischemic end organ disease.     

Diagnostic capability of optical coherence tomography in evaluating the degree of glaucomatous retinal nerve fiber damage

PURPOSE: To evaluate the role and ability of optical coherence tomography (OCT) to detect differences in peripapillary retinal nerve fiber layer (RNFL) thickness between normal and glaucomatous eyes and also between different severities of glaucoma. METHOD: This cross-sectional observational study included 160 eyes of 160 healthy subjects and 134 eyes of 134 patients with primary open-angle glaucoma (POAG). Peripapillary RNFL thickness was measured on OCT using the fast RNFL thickness protocol. The RNFL thickness parameters used for evaluation included average RNFL thickness and inferior, superior, nasal, and temporal RNFL thickness. The glaucomatous eyes were subdivided into three subgroups on the basis of visual field defects and a fourth subgroup of eyes blinded by glaucoma. RNFL thickness parameters were compared among the normal eyes and the glaucoma subgroups. Correlation of global visual field indices with RNFL thickness parameters was also performed. RESULTS: The average RNFL in control subjects, early glaucoma, moderate glaucoma, severe glaucoma, and blind glaucoma were 102.30 +/- 10.34, 77.68 +/- 15.7, 66.07 +/- 15.5, 53.65 +/- 14.2, and 44.93 +/- 4.95 microm, respectively. There was a significant difference in all RNFL thickness parameters between normal and all glaucoma subgroups (P < 0.001). Average and inferior RNFL thicknesses showed the highest area under the receiver operating characteristic curve, with 0.905 and 0.862 for normal versus early glaucoma, 0.705 and 0.722 for early versus moderate glaucoma, 0.737 and 0.717 for moderate versus severe glaucoma, and 0.635 and 0.584 for severe versus blind glaucoma. Both mean deviation (MD) and corrected pattern standard deviation (CPSD) showed a significant correlation with all the RNFL thickness parameters in eyes with glaucoma (P < 0.001). CONCLUSIONS: RNFL thickness measured on OCT may serve as useful adjuncts in accurately and more objectively distinguishing normal from glaucomatous eyes, even in the early stages of glaucoma and may help to differentiate various severities of glaucoma. Average and inferior RNFL thicknesses are among the most efficient parameters for distinguishing such a differentiation. RNFL thicknesses in eyes blinded by glaucoma provide an estimate of the component of the RNFL thickness, which is not related to visual function.     

应用SD-OCT纵向比较正常人群和青光眼进展及非进展人群的RNFL厚度

目的：应用频域光学相干断层扫描（ spectral－domain optical coherence tomography ,SD－OCT）纵向比较正常人群、青光眼进展及非进展人群的视网膜神经纤维层（ retinal nerve fiber layer ,RNFL）厚度。方法：应用SD－OCT对36例POAG患者和24例正常人监测RNFL厚度。受试者行视盘OCT、眼底照相及视野检查,每6mo一次,随访2a,至少有4次可信的OCT检查结果。根据视野及眼底照相结果将POAG患者划分为进展组和非进展组。分析各组RNFL厚度变化差异,同视野参数变化值做相关性分析。结果：平均随访2．1±0．3 a。17例被确定为POAG进展组。POAG进展组平均RNFL厚度损失速率明显高于POAG非进展组（2．46μm／a vs 1．21μm／a,P＜0．001）。下方RNFL厚度变化同视野平均偏差（ mean deviation ,MD）变化相关性最佳（r＝0．423,P＝0．03）。结论：应用SD－OCT纵向监测RNFL厚度, POAG进展者RNFL厚度丢失速率明显增高,下方RNFL厚度参数变化可能在监测中意义较大。     

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.     

GDx在青光眼早期诊断中的作用

目的:评价GDx检测RNFL厚度各参数的敏感性,特异性,准确性,阳性预测值,阴性预测值,阳性似然比,阴性似然比;比较正常人和青光眼患者GDx各参数的不同;确定GDx参数对青光眼早期诊断最有价值的指标和GDx早期诊断青光眼的能力。方法:用GDx对94例188眼正常人和88例173眼青光眼患者RNFL进行检测。将青光眼患者按视野的平均缺损程度分为早、中晚期青光眼两组。用t-test和方差分析,比较正常人RNFL参数与早、中晚期青光眼的不同;绘制GDx参数ROC曲线,比较GDx参数中ROC曲线下面积的大小;用逐步判别分析确定GDx参数中对早期青光眼诊断最有意义的指标。结果:正常人94例,平均年龄为:41.7±8.5岁;青光眼(早、中晚期)患者平均年龄:52.8±14.6岁。早期青光眼122眼,中晚期青光眼51眼,视野平均缺损(meandefect,MD;Octopus1-2-3自动视野计测量)为-1.6～23.2dB。正常人RNFL各参数与各期青光眼患者比较差异有非常显著意义(P<0.01)。GDx的TSNIT参数的敏感性和特异性为:74.0%和74.0%,准确性:86.8%,阳性预测值:73.0%,阴性预测值:76.0%,阳性似然比:2.96,阴性似然比:0.33。SA参数的敏感性和特异性为:71.1%和84.6%,准确性为77.5%,阳性预测值:80.9%,阴性预测值:76.1%,阳性似然比:4.62,阴性似然比:0.34。IA参数的敏感性和特异性为:76.3%和82.4%,准确性:78.8%,阳性预测值:80.0%,阴性预测值:79.1%,阳性似然比:4.34,阴性似然比:0.35。NFI参数的敏感性和特异性为:80.3%和67.0%,准确性:73.4%,阳性预测值:69.2%,阴性预测值:78.8%,阳性似然比:2.43,阴性似然比:0.29。GDx的TSNIT和NFI两个参数综合评价的敏感性和特异性为:76.3%和74.0%,准确性:93.3%,阳性预测值:87.7%,阴性预测值:63.2%,阳性似然比:3.05,阴性似然比:0.32。GDx两个参数综合评价时,NFI+IA结合评价的敏感性最高(88.4%),特异性最高的是SA+IA(84.6%)。如果NFI+TSNIT+SA+IA综合评价其敏感性和特异性达最高,分别是86.7%和85.6%。在特异性相同的情况下,GDx诊断早期青光眼的敏感性为66.4%,准确性:58.5%,阳性预测值:92.0%,阴性预测值:77.5%,阳性似然比:2.56,阴性似然比:0.45。中晚期青光眼诊断的敏感性为:86.3%,准确性:77.4%,阳性预测值:48.4%,阴性预测值:95.3%,阳性似然比:3.45,阴性似然比:0.18。GDx的NFI≥20时,敏感性和特异性分别为78.3%和78.7%,准确性为78.7%,阳性预测值为77.3%,阴性预测值为80.0%,阳性似然比为3.68,阴性似然比为0.28。GDx的NFI≥23时,敏感性和特异性为75.1%和84.0%,准确性为79.8%,阳性预测值为81.3%,阴性预测值为74.9%,阳性似然比为4.69,阴性似然比为0.30。GDx的NFI≥27时,敏感性和特异性分别为64.7%和91.0%,准确性为35.7%,阳性预测值为86.8%,阴性预测值为73.7%,阳性似然比为7.19,阴性似然比为0.39。GDx各参数ROC曲线下面积分别为NFI:0.84,IA:0.79,TSNIT:0.78,SA:0.77,IES:0.76。通过逐步判别分析,筛选出NFI和IA对区分早期青光眼贡献最大(F检验:P<0.01),用IA和NFI进行分析,诊断早期青光眼的敏感性和特异性分别为:88.4%和74.6%。结论:GDx为临床上提供定量检测视网膜神经纤维层厚度参数;NFI和IA是区分正常人和早期青光眼最有效指标。GDx可有助于临床上青光眼的早期诊断。     

变化角膜补偿器偏振光激光扫描仪对青光眼的临床观察

目的　评价使用变化角膜补偿器的偏振光激光扫描仪 (GDx -VCC)对青光眼患者的定量观察。方法　对青光眼患者 91人 165眼根据有无视野异常及程度分为 :青光眼视野正常组 87眼 ,早期青光眼 5 6眼及中晚期青光眼 2 2眼 ,正常人组 3 6人 3 6眼进行GDx -VCC检查。统计各组平均视神经纤维层厚度 (RNFL)、上方及下方神经纤维层厚度、平均视盘周神经纤维层厚度标准差及视神经纤维索引因素 (NFI)。对各组值进行多组比较统计处理。结果　正常人平均视神经纤维层厚度、上方及下方神经纤维层厚度与视野有异常的青光眼各组值方差分析P <0 0 0 1;与视野正常的青光眼组各对应区域的神经纤维层厚度比较P =0 0 0 9、 0 0 0 5及 0 0 64。结论　使用变化角膜补偿器的偏振光激光扫描仪测量视神经纤维层厚度对正常人与青光眼患者有区别能力 ,能更早于视野反映视神经纤维层异常。     

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.     

Comparison of retinal nerve fibre layer thickness and visual field loss between different glaucoma groups

BACKGROUND/AIMS: Scanning laser polarimetry (SLP) uses a confocal scanning laser ophthalmoscope with an integrated polarimeter to evaluate the thickness of the retinal nerve fibre layer (RNFL). The aim of this study was to verify the ability of the SLP to detect differences in RNFL thickness between normal and glaucomatous eyes and between glaucomatous eyes subdivided in groups by the severity of visual field damage. METHODS: This was a cross sectional retrospective study. The charts of 40 healthy subjects and 68 glaucoma patients who underwent complete ophthalmological examination, optic disc stereophotography, peripapillary, and macular SLP imaging were reviewed. The right eye of subjects eligible for the study was enrolled. Only eyes with SLP examinations indicating a minimised effect of anterior segment birefringence based on macular image were included. The ability of retardation parameters to discriminate between healthy and glaucomatous eyes was evaluated. Based on visual field loss, glaucoma patients were subdivided in three subgroups (early, moderate, and severe). RNFL thickness between healthy control group and glaucoma subgroups was compared. RNFL thickness and visual field loss correlation was evaluated. RESULTS: There was a significant difference in superior and inferior maximum RNFL thickness between normal and glaucomatous eyes (p<0.001). With these two parameters, the area under receiver operator characteristic curve was 0.75 and 0.74, respectively. Superior and inferior RNFL thickness was significantly different between healthy control group and all glaucoma subgroups (p<0.001) and between glaucoma subgroups (p<0.05), except for early and moderate glaucoma subgroups (p>0.05). Linear regression showed a weak correlation between RNFL thickness and visual field loss. CONCLUSION: These results suggest that once visual field loss is established, smaller reductions in the RNFL thickness detected by SLP are necessary for a given reduction of mean defect value.     

Effect of peripapillary chorioretinal atrophy on GDx parametersin patients with degenerative myopia

Purpose: To determine the effect of peripapillary chorio­retinal atrophy in degenerative myopia on the retinal nerve fibre layer (RNFL) thickness measurements performed by scanning laser polarimetry. Methods: Polarimetric RNFL analysis was done in 41 degenerative myopic eyes of 25 patients with spherical refractive errors between ?7.50 and ?22.00 D (mean ?12.50 D; SD 3.5). Analysis was also performed on 46 eyes of 24 age‐matched healthy subjects with spherical refractive errors between ?1.00 and +1.00 D (mean ?0.25 D; SD 0.50) with GDx Nerve Fiber Analyzer (Version 1.0.12). All of the myopic patients had clinically evident peripapillary chorio­retinal atrophy in their fundus examination. Results: In myopic patients most of the GDx parameters were statistically different from the control group (P < 0.05). Although average thickness, ellipse average, number, inferior maximum and inferior average were found to be higher than the healthy subjects, the modu­lation parameters and the ratio‐based parameters were significantly decreased in degenerative myopic patients (P < 0.05). The TSNIT (temporal, superior, nasal, inferior, temporal) graph showed irregular high spikes with loss of the regular double hump pattern, especially in quadrants with large chorioretinal atrophy and visible sclera. Conclusion: Peripapillary chorioretinal atrophy increased retardation values, which might be explained by the high reflectivity of the bare sclera in these areas.