The influence of low to moderate myopia on retinal nerve fiber layer as assessed by scanning laser polarimetry with variable corneal compensator

PURPOSE: To evaluate the influence of different degrees of myopia on retinal nerve fiber layer (RNFL) as measured by scanning laser polarimetry (SLP) with variable corneal compensator (VCC) in healthy eyes. METHODS: One hundred and seventy-four healthy age-matched subjects with low to high myopic and emmetropic eyes underwent RNFL measurement by means of GDxVCC. The GDx parameters included in the analysis were: Temporal-superior-nasal-inferior thickness (TSNIT) average, Superior average, Inferior average, TSNIT standard deviation, Inter-eye symmetry, NFI, Symmetry, Superior ratio, Inferior ratio, Superior/nasal, Maximum modulation, Superior maximum, Inferior maximum, Ellipse modulation, Normalized superior area, Normalized inferior area, Ellipse standard deviation, Ellipse average. The mean value of each SLP parameter of myopic eyes was compared with the mean value of the same parameter of emmetropic eyes. RESULTS: Mean myopia was 3.9 +/- 1.5 dpt (range: -2 to -8.25 dpt). TNSIT average was higher in myopic group (p = 0.0111), together with Superior average (p = 0.0244), Symmetry (p < 0.0001) and Ellipse average (p = 0.0111). Two ratio parameters, Superior ratio and Inferior ratio, were higher in emmetropic eyes (p = 0.0179 in both cases). In both the myopic and the emmetropic group, all the SLP assessments of the RNFL fell within the normal range, according to the GDx database. CONCLUSIONS: Low to high myopia is not related to clinically relevant variations of SLP parameters, as assessed with GDx-VCC.     

Intersession reproducibility of retinal nerve fiber layer thickness measurements by GDx-VCC in healthy and glaucomatous eyes

BACKGROUND: To assess intersession reproducibility of retinal nerve fiber layer (RNFL) thickness measurements on scanning laser polarimetry with variable corneal compensation (GDx-VCC) in a sample of healthy subjects and glaucoma patients. METHODS: One eye each from 29 healthy and 29 glaucomatous subjects was selected and underwent RNFL scanning by the same operator at baseline and 1 week later. Glaucoma diagnosis relied on the presence of a reproducible defect on automated perimetry. GDx-VCC parameters considered were those available on page 1 of the printout [TSNIT average and standard deviation (SD), superior and inferior average (SA, IA), Nerve Fiber Indicator]. Reproducibility was assessed by calculating coefficient of variation and intraclass correlation coefficient separately for the two groups and for each parameter. The percentage of eyes with an intersession difference in thickness parameters of more than 5% was also calculated. RESULTS: Coefficient of variation was <6% for TSNIT average, SA and IA in both groups. Corresponding values for TSNIT SD in healthy subjects and in glaucoma patients were 13.7 and 11.4%, respectively, whereas for Nerve Fiber Indicator they were 82.9 and 13.3%. Intraclass correlation coefficient ranged from 0.794 to 0.907 in healthy subjects and from 0.924 to 0.972 in glaucoma patients. In healthy subjects, TSNIT average, SA and IA intersession difference was 5% or less in 55-69% of eyes, whereas the value for TSNIT SD was 34.5%. Corresponding values in glaucomatous eyes ranged from 69 to 79.3% for TSNIT average, SA and IA and was 37.9% for TSNIT SD. CONCLUSIONS: Intersession reproducibility of RNFL thickness measurements on GDx-VCC is high, both in healthy and in glaucomatous eyes. In a few cases, however, intersession variation may be larger than 10%. Caution is necessary while interpreting these changes during follow-up, in order to separate physiological variability from real RNFL thickness variations.     

The Study of Retinal Nerve Fiber Layer Thickness of Normal Eyes Using Scanning Laser Polarimetry

Purpoe: To evaluate retinal nerve fiber layer (RNFL) thickness measurements in local normal Chinese subjects of different age groups and analyse the correlation of RNFL thickness with age using scanning laser polarimetry (SLP, GDxVCC). To assess the reproducibility of RNFL thickness measurement with GDxVCC.Methods: The RNFL thickness of 67 normal subjects (123 eyes) were measured by GDxVCC. The average TSNIT parameters were calculated. The differences of RNFL thickness between sex, right and left eyes, superior and inferior were compared. The relationship between RNFL thickness and age was analyzed with correlation analysis and linear regression analysis. The intraclass correlation coefficients (ICC) of three images in every eye were calculated.Results: The average peripapillary RNFL thickness at the superior, inferior and whole ellipse regions in 123 eyes of 67 normal subjects were (70.30±6.76)μm, (67.35±6.77) μm and (56.87±4.53) μm, respectively. The average TNSIT standard deviation was 23.68±4.61 and the average inter-eye symmetric value was 0.86±0.11. There were significant difference of RNFL thickness between superior and inferior (t=4.952,P ＜0.001 ). There were significant difference of inferior RNFL thickness and TNSIT standard deviation between right and left eyes (P=0.005 and 0.002),while not significant difference of superior RNFL thickness and whole mean RNFL thickness between right and left eye (P=0.086 and 0.529). There was no significant difference in TSNIT parameters between different genders. There was a slight negative correlation average RNFL thickness in superior sector with age (decreased approximately 0.15 microns per year,P=0.047) in the subjects aged below 60 years old. The ICC values of RNFL thickness were ＞0.8 in superior, inferior and global.Conclusions: The RNFL thickness can be measured accurately by GDxVCC and the reproducibility of RNFL thickness measurement by GDxVCC is good. There was a slight negative correlation between average RNFL thickness in superior with age. More researches on the effects of age on RNFL thickness by GDxVCC are needed.     

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.     

Diagnostic compatibility of structural and haemodynamic parameters in open‐angle glaucoma patients

Purpose: Current evidence indicates that alteration in ocular blood flow may be relevant in open‐angle glaucoma (OAG) patients independent of intraocular pressure (IOP). Presently, the lack of an adequate methodology capable of assessing all vascular beds limits the clinical role of blood flow parameters in glaucoma management. We aimed to compare differences in retinal nerve fibre layer (RNFL) thickness and retrobulbar haemodynamics between OAG patients and healthy age‐matched control subjects. Methods: Sixty eyes of 30 OAG patients and 30 healthy age‐matched controls were enrolled into the prospective, randomized study. Retinal nerve fibre layer thickness was analysed by scanning laser polarimetry (SLP). Standard SLP parameters were determined, including: average temporal, superior, nasal, inferior thickness (TSNIT); superior and inferior averages; TSNIT standard deviation (TSNIT‐SD), and nerve fibre indicator (NFI). Retrobulbar haemodynamics were assessed using colour Doppler imaging (CDI). Peak systolic velocity (PSV), end‐diastolic velocity (EDV), pulsatility index (PI) and resistivity index (RI) in the ophthalmic artery (OA), central retinal artery (CRA) and short posterior ciliary artery (SPCA) were evaluated. Results: The RNFL in OAG patients was statistically significantly thinner compared with that in age‐matched controls: the NFI was 24.9 ± 10.24 in OAG patients and 16.13 ± 7.95 in healthy controls (p < 0.05). Statistically significant differences were observed: CRA PSV was 20.54 ± 7.84 cm/second in OAG subjects and 16.5 ± 6.19 cm/second in healthy controls (p = 0.0038); OA EDV was 8.99 ± 4.71 cm/second in OAG subjects and 5.93 ± 3.23 cm/second in healthy controls (p = 0.0048). Correlation analysis of NFI was in positive association with CRA EDV (r = 0.395; p < 0.05) and CRA PI (r = 0.403; p < 0.05) in OAG subjects, but no statistically significant association was seen in healthy controls. Conclusions: Statistically significant thinning of the RNFL in association with reduced retrobulbar blood flow velocities was observed in OAG patients. Combining ocular structural alterations with ocular circulation assessment may increase our ability to elucidate potential IOP‐independent glaucomatous risk factors.     

Application of shape-based analysis methods to OCT retinal nerve fiber layer data in glaucoma

PURPOSE: (1) To evaluate the performance of shape-based analysis [wavelet-Fourier analysis (WFA) and fast Fourier analysis (FFA)] applied to retinal nerve fiber layer (RNFL) thickness values obtained from the optical coherence tomograph (OCT) to discriminate healthy and glaucomatous eyes. (2) To compare the performance of the shape-based metrics to that of the standard OCT output measures (Inferior Average and Average Thickness). METHODS: RNFL values were obtained from 152 eyes of 152 individuals (83 healthy and 69 "mild"-stage perimetric glaucoma). WFA and FFA were performed on the RNFL values and linear discriminant functions for both were obtained using Fisher linear discriminant analysis. Performance was evaluated by calculating sensitivity, specificity, and area under the receiver operating characteristic (ROC) curve (ROC area). RESULTS: The ROC area of the shape-based methods [0.94 (WFA) and 0.88 (FFA)] was greater than that of OCT metrics [0.81 (Inferior Average) and 0.74 (Average Thickness)]. Specifically, WFAs performance was significantly better than both the FFA (P=0.009) and the Inferior Average (P=0.001). Inferior average performed significantly better than Average Thickness (P=0.006). CONCLUSIONS: The ability to differentiate glaucomatous from healthy eyes using stratus OCT measurements is improved by using these analysis methods that emphasize the shape of the RNFL thickness pattern.     

GDxVCC检测原发性开角型与可疑青光眼视网膜神经纤维层损害的对比研究

目的采用GDxVCC系统检测正常人、可疑开角型青光眼(suspected open angle glaucoma，SOAG)以及原发性开角型青光眼(primary open angle glaucoma，POAG)患者的视盘周围视网膜神经纤维层(retinal nerve fiber layer，RNFL)厚度，并进行对比分析，探讨GDxVCC系统在青光眼早期诊断中的价值。设计前瞻性对照研究。研究对象42例SOAG，36例POAG以及年龄相匹配的36例正常人参加此项研究。方法所有参加者进行视野与GDxVCC系统检查，选择一眼进行分析。采用方差分析，对SOAG、POAG、正常人的RNFL参数进行两两比较。主要指标GDxVCC检测RNFL厚度。结果POAG组与正常组问所有RNFL参数差异均有极显著意义(P=0．000)；POAG组与SOAG组间所有RNFL参数差异均有极显著意义(P=0．000)；SOAG组与正常组间椭圆平均值差异无统计学意义(P=0．234)，但其上方平均值与下方平均值及神经纤维指数差异均有统计学意义(P=0．044、P=0．045、P=0．035)，TSNIT标准差有极显著意义(P=0．000)。结论GDxVCC系统能更早地发现青光眼性RNFL结构损害，不仅可用于青光眼诊断和随访，亦可用于对可疑青光眼进行追踪。     

Retinal nerve fibre layer of perimetrically unaffected eyes of glaucoma patients: an optical coherence tomography study

Purpose:  The aim of this study is to evaluate whether optical coherence tomography (StratusOCT) may detect early changes in perimetrically unaffected (PU) fellow eyes of glaucomatous patients by assessing retinal nerve fibre layer (RNFL) thickness parameters.
Methods:  Thirty-seven glaucomatous patients with unilateral field loss and 34 age-matched controls were recruited. In glaucoma patients, PU and perimetrically affected fellow eyes were analysed separately. For each group, mean values (±SD) of RNFL thickness parameters were calculated and comparisons between fellow eyes of glaucoma patients and between healthy and PU eyes of glaucoma patients conducted with paired t -test and Mann–Whitney U -test, respectively. Proportion of clock-hour sectors flagged with probability <5% or <1% was collected and differences between healthy and PU eyes were evaluated on Fisher exact test.
Results:  Global (Average Thickness) and sectoral parameters (Inferior and Nasal Average), Maximum thickness–minimum thickness (Max-min), as well as 2-o'clock (nasal side) and 6-o'clock sectors resulted significantly thinner in PU eyes than in control group. Proportion of eyes with clock-hour position flagged with probability <5% or <1% was not significantly different between healthy and PU eyes.
Conclusion:  Despite a standard automated perimetry within normal limits, the StratusOCT detected both localized and diffuse RNFL thinning in PU eyes of glaucoma patients. These eyes should be considered at risk of developing functional damage over time and consequently require thorough monitoring for detecting any sign of progression.     

Comparison of Spectralis-OCT, GDxVCC and GDxECC in assessing retinal nerve fiber layer (RNFL) in glaucomatous patients

Background

Glaucomatous optic neuropathy is characterized by a progressive loss of retinal ganglion cells (RGCs). The defects in the peripapillary retinal nerve fiber layer (RNFL) have been reported to be the earliest sign of glaucoma. We determined the agreement between RNFL thickness assessments from spectral-domain OCT (Spectarlis HRA?+?OCT; Heidelberg Engeneering, Heidelberg, Germany), scanning laser polarimetry (SLP) with variable cornea compensation (GDxVCC; Carl Zeiss Meditec, Dublin, CA, USA), and SLP with enhanced cornea compensation (GDxECC; Carl Zeiss Meditec, Dublin, CA, USA) in glaucomatous patients. Furthermore, we investigate the influence of typical scan score (TSS) on the results of GDx assessments.

Methods

The enrolled subjects were devided into different groups by modified HODAPP visual field criteria. The peripapillary RNFL thickness was assessed with the three devices . ANOVA test, Pearson and Spearman correlation coefficient, and Bland-Altman plots were used to analyse the RNFL thickness assessments.

Results

Ninety-two eyes from 92 glaucomatous subjects were analysed. These were divided into four groups: preperimetric glaucoma (n?=?26), mild glaucoma (n?=?18), moderate glaucoma (n?=?21), and severe glaucoma (n?=?27). For Spectralis-OCT, the average RNFL thickness (mean ± SD) was 99.25?±?26.31 μm, 80.52?±?16.63 μm, 71.59?±?21.15 μm, and 63.85?±?20.86 μm for preperimetric, mild, moderate, and severe glaucoma respectively. For GDxVCC, the corresponding assessments were 52.63?±?8.18 μm, 52.95?±?10.20 μm, 46.77?±?10.62 μm, and 49.70?±?13.34 μm. For GDxECC, the assessments were 49.35?±?6.52 μm, 45.92?±?7.21 μm, 42.19?±?8.00 μm, and 39.53?±?8.45 μm. All Spectralis-GDxVCC and Spectralis-GDxECC differences were statistically significant by ANOVA test. The differences between GDxVCC and GDxECC were statistically significant only for severe glaucoma. There was a highly significant correlation between Spectralis-OCT and GDxECC, as well as Spectralis-OCT and GDxVCC, in assessing the RNFL thickness. The best instrument agreement was found between GDxECC and Spectralis-OCT. The RNFL thickness assessed with Spectralis-OCT and GDxECC showed a better correlation to visual field defects than GDxVCC. Evaluating GDx assessments with typical retardation pattern GDxVCC and GDxECC showed very similar RNFL thickness results.

Conclusions

RNFL thickness assessments between GDxVCC, GDxECC, and Spectralis-OCT cannot be directly compared. The assessments are generally higher with Spectralis-OCT than with GDxVCC and GDxECC, because of differences in method of the devices. The atypical retardation pattern has a major impact on the RNFL thickness results of GDx devices. This must be taken into account when evaluating the assessed RNFL thickness results.     

Assessment of peripapillary retinal nerve fiber layer thickness using scanning laser polarimetry (GDx VCC) in normal Indian children

Purpose:

To obtain reference values of RNFL thickness in normal Indian children and to study the association of RNFL thickness with central corneal thickness(CCT) and axial length(AL).

Materials and Methods:

200 normal Indian children (mean age 8.6 ± 2.9 yrs) were examined on the GDxVCC. The inferior average (IA), superior average (SA), temporal-superior-nasal-inferior-temporal (TSNIT) average and nerve fiber index (NFI) values were recorded and compared between males and females as well as between the different age groups. The association of TSNIT average with AL and CCT was examined.

Results:

Values for the RNFL parameters were-SA: 64.9 ± 9.7, IA: 63.8 ± 8.8, TSNIT average: 53.5 ± 7.7 and NFI 21.5 ± 10.8. Superior, inferior and TSNIT averages did not differ significantly between males and females (P = 0.25, P = 0.19, P = 0.06 respectively; Mann-Whitney U test). No significant differences were found in TSNIT average across age groups. There was a statistically significant positive correlation between CCT and TSNIT average (r = 0.25, r² = 0.06, P < 0.001). The correlation TSNIT average and AL(r = −0.12; r² = 0.01) was not significant (P = 0.2).

Conclusion:

Reference values for RNFL parameters reported for Indian children are similar those reported in adults. There is a small correlation between central corneal thickness and RNFL as reflected in average TSNIT.     

Correlation between optic disc area and retinal nerve fiber layer thickness: a study on scanning laser polarimetry with variable corneal compensation

Purpose To evaluate if a significant increase of the peripapillary retinal nerve fiber layer (RNFL) thickness can be measured in a sample of healthy eyes by means of scanning laser polarimetry with variable corneal compensation (GDx-VCC) as the optic disc (OD) area increases. Methods One eye each of 232 healthy subjects (mean age: 57.8 years; range:40–70) was considered. Temporal-superior-nasal-inferior-temporal average (TSNIT Avg) and OD area (area within the ellipse placed on inner border of peripapillary scleral ring) values were collected. Ellipse horizontal and vertical diameters provided on printout were used to estimate OD area using the equation: OD area = π × horizontal radius×vertical radius. TSNIT Avg values were plotted against OD area and a multiple linear regression including age calculated. Results Mean OD area was 2.19 mm²±0.45 (range: 1.23–3.59) and mean TSNIT Avg was 54.3 μ ± 3.2 (range: 45.8–61.8). Multiple linear regression equation was TSNIT Avg=57.7−0.096×OD Area−0.055×Age (Pearson r=−0.146: p=0.086) Conclusion In our sample of healthy eyes, no significant correlation was found between TSNIT Avg and OD area. In spite of a shorter distance between OD and measurement ellipse margins, larger discs did not necessarily show a thicker RNFL. Probably the large inter-subject variability for RNFL thickness, and then for axonal count, was a predominant factor over OD area. None of the authors have any financial or proprietary interest with products cited in the text.     

Scanning laser polarimetry with variable corneal compensation in migraine patients

Purpose: This study aimed to compare scanning laser polarimetry measurements of retinal nerve fibre layer (RNFL) thickness in eyes of migraine patients with those in eyes of age‐matched, healthy subjects. Methods: The study was designed as an observational, prospective, cross‐sectional study. It included 57 eyes of 57 patients with migraine with or without aura according to the criteria of the International Headache Society and 44 eyes of 44 age‐matched healthy controls. Scanning laser polarimetry images were obtained using a commercial GDx VCC system (Version 5.3.1; Laser Diagnostic Technologies, Inc.). At each sitting, three sets of GDx VCC measurements were acquired for each patient and used in the analysis. Image acquisition was performed in undilated eyes in all subjects. Results: The mean ± standard deviation RNFL average thickness parameter in the migraine subjects was significantly lower than in the control group, at 50.4 ± 4.8 μm versus 54.7 ± 3.4 μm, respectively (p < 0.0001). However, there were no differences between migraine subjects and controls in mean RNFL thickness in superior and inferior areas. In the migraine group the mean migraine disability assessment (MIDAS) score was 34.3 ± 15.3 and the mean number of attacks per year was 17.1 ± 6.9 (range 6?28). The mean RNFL average thickness parameter was significantly correlated with MIDAS score (r = ? 0.86, p < 0.0001) and frequency of attacks (r = ? 0.86, p < 0.0001). Conclusions: The mean RNFL average thickness parameter was found to be thinner in migraine patients. In addition, we found a strong correlation between migraine severity and RNFL average thickness parameters.     

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。     

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.     

Stratus OCT与GDxVCC测量正常人与青光眼患者视网膜神经纤维层厚度比较研究

目的 比较相干光断层扫描仪StratusOCT与激光偏振光视网膜扫描仪GDxVCC测量视网膜神经纤维层(RNFL)厚度的相关性及差异,探讨两者测量值与视野的相关性及其对青光眼的诊断效能.方法 84例原发性开角型青光眼(POAG)患者及50名正常人,随机选取一眼进行StratusOCT和GDxVCCRNFL厚度测量及Humphery自动视野计检查.相关分析比较两种仪器测量的全周、上方、下方RNFL厚度;回归分析研究视野的平均偏差与两种仪器测量的RNFL厚度值之间的关系;ROC曲线下面积分析两种仪器诊断青光眼的效能.结果 Stratus OCT测量正常人及POAG患者的全周RNFL厚度分别为(100.00±7.36)μm和(75.12±17.11)μm,GDxVCC对应测量值(57.16±5.05)μm和(48.00.4±8.46)μm.两种仪器测量的RNFL厚度呈线性相关(r>0.75).两种仪器测量的RNFL厚度值与视野的平均偏差呈正相关,三次曲线拟合度较直线相关的拟合度好.对于青光眼诊断,Stratus OCT的最大ROC曲线下面积为0.908,GDxVCC最大ROC曲线下面积为0.842.结论 Stratus OCT与GDxVCC测量RNFL厚度值存在差异,但两者呈线性相关,均与视野的平均偏差呈曲线相关.两种仪器诊断青光眼的效能均较好.     

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.     

Multicenter Spanish study of spectral‐domain optical coherence tomography in normal children

Purpose: To compile a multicenter normative database of retinal nerve fibre layer (RNFL) and macular thicknesses and macular volume values in healthy Caucasian children 4–17 years using spectral‐domain optical coherence tomography (SD‐OCT). To analyse variations in the OCT measurements as a function of age, sex, refraction, and axial length (AL). Methods: An observational, multicenter and cross‐sectional study among 301 healthy Caucasian children recruited at three Spanish centres was performed. To compile the database, each child underwent a dilated eye examination and a cycloplegic refraction, five AL measurements (IOL Master; Carl Zeiss Meditec, Dublin, CA, USA), five OCT scans with Cirrus OCT: three peripapillary RNFL scans (Optic Disc Cube 200X200 protocol) and two macular scans (Macular Cube 512X128 protocol). One eye of each subject was selected randomly for analysis. Results: Two hundred eighty‐three children (117 boys, 41.34%; 166 girls, 58.66%) were included in this study. The mean age of the children was 9.58 ± 3.12 years (range, 4–17). The mean SE was +0.63 ± 1.65 D; (range, ?4.88 to +5.25). The mean AL was 22.94 ± 1.10 mm (range, 20.10–26.27). The mean global RNFL thickness was 97.40 ± 9.0 μm (range, 77–121.7 μm). Multivariate analysis showed a positive correlation between the RNFL and spherical equivalent (SE) (p = 0.014). The mean central macular thickness was 253.85 ± 19.76 μm, the average thickness 283.62 ± 14.08 μm, and the mean macular volume 10.22 ± 0.49 μm³. Multivariate analysis showed a positive correlation between central macular thickness and age (p < 0.001). Boys had a significantly thicker central macula than girls (p < 0.001). Conclusions: Normative paediatric SD‐OCT data might facilitate use of SD‐OCT for assessing childhood ophthalmic diseases. This study provides a multicenter paediatric normative database of SD‐OCT peripapillary RNFL and macular data.     

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.     

Glaucoma detection using different Stratus optical coherence tomography protocols

PURPOSE: To examine and compare the diagnostic accuracy of retinal nerve fibre layer (RNFL) thickness measurements using different Stratus optical coherence tomography (OCT) scanning protocols. METHODS: Stratus OCT data for 90 healthy subjects and 62 glaucoma patients with mild or moderate visual field loss were prospectively collected and analysed using four RNFL thickness protocols that differed in terms of image resolution and number of scans. Cut-off levels corrected for age and refractive error were defined by reference values derived from an independent normal database. Sensitivity and specificity were calculated for average RNFL thickness for the full circle scan, and for the quadrant and clock hour circle scan sectors at p < 5% and p < 1% cut-off values. RESULTS: Regular- and high-resolution images performed equally well, and single best-quality scans were as good as the average of three scans to distinguish between healthy and glaucomatous eyes. Full circle RNFL thickness yielded similar or better diagnostic accuracy than that of sectors. Sensitivities ranged from 84% to 87% and specificities from 89% to 93% for full circle RNFL thickness at the p < 5% cut-off level. CONCLUSIONS: The abilities of four different Stratus OCT RNFL thickness protocols to distinguish between eyes with predominantly mild glaucomatous field loss and healthy eyes were very similar. Thus diagnostic accuracy did not differ between high- and regular-resolution protocols, nor between global (full circle) and localized (sector) OCT parameters, which suggests a diffuse component in early glaucomatous RNFL damage.     

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.