Correlation between optic nerve head parameters and retinal nerve fibre layer thickness measured by spectral-domain optical coherence tomography in myopic eyes

Background: To evaluate the correlation between optic nerve head parameters and retinal nerve fiber layer thickness measured by Cirrus HD spectral‐domain optical coherence tomography (Cirrus HD‐OCT; Carl Zeiss Meditec) in healthy myopic eyes. Design: Cross‐sectional study. Participants: One hundred and sixty‐one right eyes from 161 healthy young myopic subjects. Methods: Optic nerve head parameters and retinal nerve fiber layer thickness were measured with the Cirrus HD‐OCT. The distance between optic disc margin and scan circle (disc margin‐to‐scan distance) was measured on the Cirrus HD‐OCT en‐face optic nerve head image with aid of National Institutes of Health ImageJ image‐analysis software (developed by Wayne Rasbands, National Institutes of Health, Bethesda, MD). Main Outcome Measures: The correlations among optic nerve head parameters, retinal nerve fibre layer thickness and the disc margin‐to‐scan distance were evaluated with and without adjustment of the magnification effect. Results: Without correction of the magnification effect, the thicker average retinal nerve fiber layer was correlated with greater rim area and lower degree of myopia (P < 0.001). When the magnification effect was corrected, thicker average retinal nerve fibre layer was associated with greater disc area and greater rim area in univariate and multivariate analyses (P ≤ 0.028); however, degrees of myopia and the disc margin‐to‐scan distance were not significantly associated with average RNFL thickness (P ≥ 0.104). Conclusions: Thicker average retinal nerve fibre layer thickness was associated with greater rim and disc areas. Disc margin‐to‐scan distance was not significantly correlated with average retinal nerve fibre layer thickness in healthy myopic eyes.     

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.     

光学相干断层成像术检测近视眼视网膜神经纤维层厚度的特点

目的:探讨光学相干断层成像术(optical coherence tomography,OCT)检测近视眼视盘周围视网膜神经纤维层(ret-inal nerve fiber layer,RNFL)厚度的特点及其与屈光度的关系。方法:对5~40岁正常对照眼61例68眼,近视眼152例205眼,应用Stratus OCTTM3000,RNFL3.4程序对视盘为中心直径3.4mm的RNFL进行检测。结果:近视眼RFNL厚度7∶00和11∶00位最大,3∶00位最小,上象限(S)、下象限(I)平均值接近并(颞侧象限平均值(T)(鼻侧象限平均值(N)。正常眼组与低度、中度和高度近视眼组对应RNFL厚度相关参数组间比较:7∶00和11∶00,Smax,Imax,Smax/Imax,Max-Min差异均无显著性,3∶00、4∶00和N差异均有显著性。控制年龄因素条件下,近视眼RNFL厚度部分参数(上方和鼻侧居多)与等效球镜度数有较弱的负线性相关直线趋势,而部分参数(下方和颞侧居多)与等效球镜度数无直线性相关趋势。结论:近视眼视盘鼻侧RNFL厚度已变薄,中度和高度近视眼更明显,而颞侧和颞下RNFL变化不明显。     

Comparison of retinal nerve fibre layer measurements from time domain and spectral domain optical coherence tomography systems

Objective: To compare retinal nerve fibre layer (RNFL) thickness measurements acquired using spectral domain (SD) and time domain (TD) optical coherence tomography (OCT) systems.Study Design: Prospective clinical study.Participants: Twenty eyes of 20 healthy volunteers.Methods: All patients underwent 3 sets of circular OCT scans around the optic disc using both a TD OCT system, and a new SD OCT system. RNFL thickness measures within each of 4 quadrants, as well as overall mean RNFL thickness, were compared. Bland-Altman plots were also used to assess agreement.Results: Using the RTVue-100, RNFL measurements in the superior quadrant were, on average, 20 μm greater than those obtained from the Stratus (151.8 μm vs 131.7 μm, p < 0.0001). RNFL measures within other quadrants and overall mean RNFL thickness were not significantly different between systems. Bland-Altman plots indicated large differences between Stratus and RTVue-100 for all variables, with 95% limits of agreement spanning clinically important ranges of >50 μm for all RNFL variables.Conclusions: Significant differences exist between RNFL measurements obtained from the TD and SD OCT systems used in this study. These related, but distinct, technologies are not interchangeable. Further studies will be required to allow for appropriate clinical use of new SD OCT systems.     

Scleral thickness in highly myopic eyes measured by enhanced depth imaging optical coherence tomography

Purpose

The purpose of this study was to determine the subfoveal scleral thickness in highly myopic eyes by enhanced depth imaging spectral-domain optical coherence tomography (EDI-OCT) and to identify the ocular parameters significantly associated with the scleral thickness.

Methods

The subfoveal scleral thickness of myopic eyes (≥−8 diopters (D) or axial length ≥26.5 mm) was examined by EDI-OCT. The correlations between the thickness and the best-corrected visual acuity (BCVA), refractive error, axial length (AL), the subfoveal retinal thickness, choroidal thickness, and posterior staphyloma height 2 mm from the fovea were investigated.

Results

A total of 75 eyes of 54 patients (21 men, 33 women; mean age, 62.3±11.3 years; mean AL, 30.2±1.68 mm) were studied. Eighteen eyes had no pathological retinochoroidal lesions, and 57 eyes had retinochoroidal lesion, that is, myopic schisis, choroidal neovascularization, and other retinochoroidal pathologies. The mean subfoveal scleral thickness was 284.0±70.4 μm, and the thickness was significantly correlated negatively with the absolute value of the nasal and overall average posterior staphyloma height (P<0.05 and P<0.01, respectively). The subfoveal scleral thickness was also significantly correlated negatively with the relative value of the superior, nasal, and overall average posterior staphyloma height (P<0.05, P<0.01, and P<0.001, respectively). Stepwise analyses showed that the factor most significantly associated with the scleral thickness was the average relative posterior staphyloma height (F=16.0, P<0.001). The scleral thickness was not significantly different between eyes with and without myopic retinochoroidal pathologies (P>0.05).

Conclusion

Posterior staphyloma formation was a key factor associated with a posterior scleral thinning in highly myopic eyes.     

Stratus相干光断层扫描仪测量正常人视网膜神经纤维层的厚度

目的建立Stratus OCT测量我国正常人视网膜神经纤维层(RNFL)厚度的正常值,探讨正常人RNFL厚度的变异程度和与年龄及性别的关系。设计前瞻性横断面研究。研究对象10～69岁的正常人。方法用Stratus OCT的扫描程序(Fast RNFL Thickness 3.4)对210例(210眼)正常人进行视乳头环形扫描,测量各象限和平均RNFL厚度值,应用SPSS 11.5软件统计学处理。主要指标RNFL厚度值。结果210例正常人上方象限、颞侧象限、下方象限、鼻侧象限及全周平均的RNFL厚度分别为(145.5±16.8)、(84.2±12.8)、(147.6±15.2)、(84.7±14.2)μm。平均RNFL厚度变异最小,鼻侧RNFL厚度变异最大。除鼻侧象限外,其它各象限及平均RNFL厚度与年龄均呈负相关性。对正常人RNFL厚度无性别差异。结论用Stratus OCT测量的正常人RNFL厚度数值中,平均RNFL厚度变异最小,鼻侧RNFL厚度变异最大;RNFL厚度随年龄增长而变薄。     

Comparison of the influence of cataract and pupil size on retinal nerve fibre layer thickness measurements with time-domain and spectral-domain optical coherence tomography

Background: To investigate and compare the effect of cataract and pupil size on retinal nerve fibre layer (RNFL) thickness measurements using spectral‐domain optical coherence tomography (Cirrus OCT) and time‐domain OCT (Stratus OCT). Design: Prospective, hospital‐based study. Participants: Twenty‐five eyes from 25 normal subjects undergoing cataract surgery. Methods: Three retinal nerve fibre layer (RNFL) thickness measurements were taken before and after dilation, preoperatively and postoperatively, using Cirrus 200 × 200 Optic Disc Scan and Stratus Fast RNFL Scan. Main Outcome Measures: Linear regression, intraclass correlation coefficient (ICC) and coefficient of variation analysis. Results: Cataract removal caused significant increase in RNFL measurements in both modalities (Cirrus P < 0.02; Stratus P < 0.001). There was no significant difference in the increase in measurements between the two machines. Pupil dilation had variable and non‐statistically significant effect in both (P > 0.05). ICC showed excellent reproducibility with Cirrus OCT after mydriasis, preoperatively (ICC = 0.78–0.90) and postoperatively (ICC = 0.90–0.97), but poor reproducibility before mydriasis (P < 0.75). Stratus OCT achieved excellent reproducibility after cataract removal both before (ICC = 0.86–0.96) and after mydriasis (ICC = 0.92–0.95), but poor reproducibility before cataract surgery (P < 0.75). Conclusions: Cataracts, not pupil size, cause significant underestimation of RNFL measurements in both Cirrus and Stratus OCT. The extent of influence exerted does not appear different between the two instruments. Reproducibility of each machine appears to be affected differently. Mydriasis is required to achieve excellent reproducibility with Cirrus OCT, and media clarity is required with Stratus OCT.     

Application of optical coherence tomography in glaucoma suspect eyes

Purpose: The aim of the study was to compare the optical coherence tomography (OCT) parameters of the optic nerve head (ONH) and retinal nerve fibre layer (RNFL) and to identify which measurements are best able to differentiate between normal and glaucoma suspect eyes. Methods: The study included 27 eyes with ocular hypertension (OHT), 33 eyes with pre‐perimetric glaucoma (PG), 30 perimetrically unaffected eyes of patients with glaucoma in the fellow eye (FE) and 58 eyes of age‐matched normal volunteers. All subjects underwent a complete eye examination with standard automated perimetry, optic disc photography and OCT imaging. Peripapillary ‘fast RNFL thickness scans’ and ‘fast optic disc scans’ were performed with time‐domain OCT. The ONH and RNFL parameters were compared among the four study groups. The ONH and RNFL parameters were examined alone and then combined via four linear discriminant functions (LDF): LDF 1, the optimal combination of ONH parameters; LDF 2, the optimal combination of RNFL parameters; LDF 3, the optimal combination of both ONH and RNFL parameters; and LDF 4, the optimal combination of the best 11 parameters. The areas under the receiver operating curves (AUC) and the sensitivity at fixed specificity of at least 80 and 95 per cent were calculated for single parameters and LDF combinations and then compared. The best 11 parameters were selected based on their AUC values. Results: Comparative analysis of OCT parameters revealed statistically significant differences in all seven ONH parameters in both PG and FE groups (and only in one ONH measurement in the ocular hypertensive group) when compared with normal eyes. Most of the RNFL parameters demonstrated statistically significant differences in all of the study groups when compared with the control group. The max‐min parameter (0.835), inferior quadrant (0.833) and average RNFL thickness (0.829) obtained the highest AUC values in the whole glaucoma suspect group. The rim area had the best diagnostic accuracy among the ONH parameters (AUC = 0.817). The AUC values of the four LDF were: 0.825 (LDF 1), 0.882 (LDF 2), 0.902 (LDF 3) and 0.888 (LDF 4). Statistically significant differences were found between the AUC values of the single best ONH and RNFL parameters and LDF 3 and LDF 4. Conclusions: In the present study, RNFL parameters presented with better discriminatory abilities than ONH parameters in the OHT and FE groups. The ONH parameters demonstrated better diagnostic precision in differentiating between PG and normal eyes. The average RNFL thickness, max–min parameter and inferior quadrant RNFL thickness had the best abilities among single OCT measurements for discriminating between glaucoma suspect (including all ocular hypertensive, PG and FE eyes) and normal eyes. The combination of RNFL parameters only or both ONH and RNFL parameters, using linear discriminant analysis, provided the best classification results, improving the diagnostic accuracy of the instrument.     

Cirrus HD OCT检测近视眼视网膜神经纤维层厚度的研究

目的：应用Cirrus HD OCT检测近视眼视网膜神纤维层厚度,探讨近视眼神经纤维层厚度分布特点及其与屈光度的关系。 方法：将近视眼106例196眼分为低、中、高度近视组和正常对照组38例60眼,应用Cirrus HD OCT进行以视盘为中心,直径3.46 mm圆周的RNFL厚度测量,计算各组平均、各象限及各钟点RNFL厚度,各近视组分别与正常对照组对比,研究近视眼RNFL厚度与屈光度的关系。 结果：各近视组平均、上方象限及下方象限RNFL厚度较正常对照组变薄,其中中度、高度近视与正常对照组相比有统计学差异（ P〈0.05）,鼻侧象限RNFL厚度变薄,无统计学显著性差异（ P〉0.05）,颞侧象限RNFL厚度增加,有统计学差异（ P〈0.05）;各近视组2：00,6：00,12：00位RNFL厚度较正常对照组变薄,有统计学差异（ P〈0.05）,8：00,9：00,10：00位RNFL厚度较正常对照组增加,有统计学差异（ P〈0.05）,中、高度近视1：00,5：00位厚度较正常对照组变薄,有统计学差异（P〈0.05）。 结论：近视眼平均、上方及下方象限、2：00,6：00,12：00位RNFL厚度较正常对照组变薄,颞侧象限、8：00,9：00,10：00位RNFL厚度较正常对照组相比明显增加,这是近视眼RNFL厚度的特点,当临床出现RNFL厚度异常时,应考虑屈光度的影响,综合评价其临床意义;近视眼7：00,8：00,10：00,11：00位RNFL厚度与正常对照组相比均未变薄,出现异常变薄时,应考虑青光眼可能。     

Evaluating glaucomatous abnormality in peripapillary optical coherence tomography enface visualisation of the retinal nerve fibre layer reflectance

Purpose

Optical coherence tomography (OCT ) enface visualisation of the retinal nerve fibre layer (RNFL ) reflectance has been found to have some advantages over retinal thickness measures. However, it is not yet clear how abnormalities on enface images relate to findings of abnormalities from other clinical measures such as the circumpapillary retinal nerve fibre layer thickness (cRNFLT ). We developed a technique to analyse the RNFL reflectance on the OCT enface images, and to investigate its relation with the cRNFLT .

Methods

Spectralis ( www.heidelbergengineering.com ) OCT scans of the central retinal ±24° were analysed in the study eye of 31 controls and 33 patients, ages 61 (±9) and 69 (±8) years respectively. Enface slab‐images were extracted at 16–24, 24–36, and 24–52 μm from the inner limiting membrane in the temporal raphe, perifoveal and disc regions respectively. Reflectance probability maps were generated for the patients based on the control data. Glaucomatous abnormality was defined on the slab‐images when the slab‐area with reflectance abnormality was greater than the 95th percentile, and on the cRNFLT when the thickness measure was less than the fifth percentile, of that found in controls. The fraction of slab‐image showing reflectance abnormality was compared to cRNFLT in the patient group, using Spearman's rho. Agreement between the findings of abnormality based on cRNFLT and slab‐image reflectance was assessed using Cohen's kappa.

Results

Slab‐image and cRNFLT findings were in agreement for 26/33 eyes; four subjects showed cRNFLT abnormality but not slab‐image abnormality, and three subjects showed slab‐image abnormality but not cRNFLT abnormality. Spearman's rho found r _s(31) = ?0.82. The reflectance findings and cRNFLT findings were consistent in 27/33 for both the superior temporal (ST ) and inferior temporal (IT ) sectors, and Cohen's kappa found 0.53 and 0.61 respectively.

Conclusion

The surface area of enface slab‐images showing RNFL reflectance were strongly related to the cRNFLT measures, and the classification of a subject with glaucoma based on enface reflectance findings and cRNFLT findings had a generally good agreement. The larger retinal area assessed by the enface method preserves the spatial location of the RNFL abnormalities, and makes the technique a useful approach for identifying regions of potential RNFL abnormality for targeted perimetry.

     

Diagnostic capability of peripapillary retinal nerve fiber layer parameters in time-domain versus spectral-domain optical coherence tomography for assessing glaucoma in high myopia

AIM: To evaluate and compare the diagnostic capabilities of peripapillary retinal nerve fiber layer (p-RNFL) parameters of Spectralis optical coherence tomography (OCT) versus Stratus OCT to detect glaucoma in patients with high myopia. METHODS: This is a retrospective, cross-sectional study. Sixty highly myopic eyes of 60 patients were enrolled, with 30 eyes in the glaucoma group and 30 eyes in the control group. All eyes received peripapillary imaging of the optic disc using Stratus and Spectralis OCT. Areas under the receiver operating characteristic curve (AUROC) and the sensitivity at specificity of >80% and >95% for p-RNFL parameters obtained using the two devices to diagnose glaucoma were analysed and compared. RESULTS: In Spectralis OCT, p-RNFL thickness parameters with the largest AUROC were the temporal-inferior sector (0.974) and the inferior quadrant (0.951), whereas in Stratus OCT, the best parameters were the 7-o’clock sector (0.918) and the inferior quadrant (0.918). Compared to the Stratus OCT parameters, the Spectralis OCT parameters demonstrated generally higher AUROC; however, the difference was not statistically significant. CONCLUSION: The best p-RNFL parameters for diagnosing glaucoma in patients with high myopia were the temporal-inferior sector on Spectralis OCT and the 7-o’clock sector on Stratus OCT. There were no significant differences between the AUROCs for Spectralis OCT and Stratus OCT, which suggest that the glaucoma diagnostic capabilities of these two devices in patients with high myopia are similar.     

Nerve fibre layer thinning in patients with preclinical retinopathy

Objective: To compare retinal nerve fibre layer thickness (RNFLT) obtained by optical coherence tomography (OCT) between patients with preclinical diabetic retinopathy (DR) and healthy subjects.Study Design: Cross-sectional study.Participants: Ninety-nine type I or II diabetic patients with no visible funduscopic retinal alteration and 77 healthy subjects were included in this study.Methods: All participants were evaluated for peripapillary RNFLT by Stratus OCT. In diabetic patients, levels of blood sugar and glycosylated hemoglobin were examined.Results: The mean RNFLT in diabetic patients and healthy subjects was significantly different (104.2 [SD 10.4] and 108.6 [SD 9.2] mm, respectively; p = 0.004). Compared with the healthy group, the RNFLT in the diabetic group was also significantly less in the superior quadrant and at the 5,11, and 12 o'clock sectors (p = 0.04, 0.002, and 0.001, respectively). The average RNFLT in diabetic patients with preclinical DR showed a low correlation with fasting blood sugar level (p = 0.03).Conclusions: The mean and superior quadrant peripapillary RNFLT was slightly less in diabetic patients without abnormal vascular manifestations than in healthy subjects. Furthermore, lower RNFLT values in patients with pre- clinical DR appears to be weakly associated with high levels of fasting blood sugar.     

Discriminating ability of optical coherence tomography data in staging glaucomatous damage

Objective: To evaluate the ability of retinal nerve fibre layer (RNFL) thickness and optic nerve head (ONH) measurements, as determined by optical coherence tomography (OCT), to discriminate between normal eyesight and glaucoma and also among the different stages of glaucoma.Design: Observational cross-sectional study.Participants: Eighty-one controls and 213 glaucoma patients were enrolled in the study.Methods: The discriminating powers of OCT parameters for the detection of glaucoma and subgroups were compared by the area under the receiver operating characteristic (AUROC) curves.Results: The best RNFL thickness parameters for discriminating between early glaucoma and control eyes were inferior (0.74 [SE 0.04] μm), average (0.74 [SD 0.03] μm), and superior (0.68 [SD 0.03] μm). Among the ONH parameters, the best AUROC curve values were cup area (0.83 [SD 0.33]), cup/disc (C/D) area ratio (0.82 [SD 0.03]), and vertical integrated rim area (VIRA) (0.82 [SD 0.03]). The best AUROC values belonged to the RNFL thickness and were inferior (0.80 [SD 0.03]), superior (0.79 [SD 0.03]), and 6 o’clock (0.78 [SD 0.03]). The highest AUROC values were horizontal integrated rim width (HIRW) (0.74 [SD 0.04]), VIRA (0.64 [SD 0.04]), and rim area (0.63 [SD 0.04]) among the ONH parameters for early versus moderate glaucoma. The best AUROC values were inferior (0.81 [SD 0.03]), 6 o’clock (0.79 [SD 0.03]), and superior (0.78 [SD 0.04]) among the RNFL, and the best AUROC values were cup area (0.81 [SD 0.03]),VIRA (0.81 [SD 0.03]), and C/D area ratio (0.80 [SD 0.03]) among the ONH parameters, for moderate versus advanced glaucoma.Conclusions: RNFL and ONH OCT parameters might provide information for determining glaucomatous damage.