A population‐based study of macular thickness in full‐term children assessed with Stratus OCT: normative data and repeatability

Purpose: We aimed to determine normal macular thickness values, assessed with optical coherence tomography (OCT), in a population of full‐term children of normal birthweight. Methods: A total of 56 children, aged 5–16 years, randomly chosen from the population register, were examined with Stratus OCT. Only children with visual acuity < 0.2 logMAR, spherical equivalent of ? 3 to + 3 D and astigmatism < 2 D were included. The fast macular map protocol was used and three examinations were performed in each eye. One eye was then randomized for further analyses. Mean values for the nine ETDRS areas, foveal minimum thickness and macular volume were calculated for 55 eyes. Coefficients of variance and intraclass correlations were calculated for each area. Results: All children co‐operated well and no child was excluded for lack of concentration. Mean ± standard deviation central macular thickness was 204 ± 19 μm. Mean total macular volume was 7.11 ± 0.35 mm³. No correlations were found between age, gender and macular thickness. Coefficients of variance were < 2% and intraclass correlations were > 0.9 in all areas, except the foveal minimum. Conclusions: Normal values for macular thickness in healthy full‐term children were reported. As the Stratus OCT provides normal values only for adults, these data are a better alternative for comparison with children with retinal abnormalities. We concluded that OCT is suitable for examining the retina in children aged 5–16 years and has the same high level of repeatability as in adults.     

频域OCT测量正常学龄期儿童黄斑区视网膜厚度

目的　应用频域ＯＣＴ测量正常学龄期儿童的黄斑区视网膜厚度。方法　选取６～１２岁儿童１０８人,以最佳矫正远视力≥１．０、最佳矫正近视力Ｊｒ１、球镜屈光度范围（－１．００～＋１．００Ｄ）、柱镜屈光度范围（－１．００～＋１．００Ｄ）为纳入标准,最终选取２１３眼。应用ＣｉｒｒｕｓＨＤ-ＯＣＴ的２００×２００扫描模式和５１２×２１８扫描模式对受试者双眼黄斑区视网膜进行检查,测量黄斑中心视网膜厚度（ｃｅｎｔｒａｌｓｕｂｆｉｅｌｄｔｈｉｃｋｎｅｓｓ,ＣＳＴ）、黄斑区视网膜容积（ｍａｃｕｌａｒｖｏｌｕｍｅ,ＭＶ）、黄斑区平均视网膜厚度（ａｖｅｒａｇｅｍａｃｕｌａｒｔｈｉｃｋｎｅｓｓ,ＡＭＴ）及九分区模式视网膜厚度。结果　两种扫描模式下黄斑区视网膜厚度值差异均无统计学意义（均为Ｐ＞０．０５）。左右眼差异无统计学意义（均为Ｐ＞０．０５）。男童ＣＳＴ（２４０．６８±１６．５７）μｍ厚于女童（２３４．５１±１８．６５）μｍ（Ｐ＝０．０４０）,且男童内环各分区视网膜厚度均厚于女童（均为Ｐ＜０．０５）。结论　本研究应用ＨＤ-ＯＣＴ测量正常儿童ＡＭＴ,为确定国人学龄期儿童ＡＭＴ正常值及疾病诊断提供参考,提示临床注意性别差异。     

Retinal nerve fibre layer thickness in full‐term children assessed with Heidelberg retinal tomography and optical coherence tomography: normal values and interocular asymmetry

Purpose: This study aimed to investigate normal values and interocular differences in retinal nerve fibre layer (RNFL) thickness, using optical coherence tomography (OCT) and Heidelberg retinal tomography (HRT), in 5–16‐year‐old children born at full‐term with normal birthweights. Methods: Fifty‐six children with normal visual acuity and refraction were examined with Stratus OCT and HRT. Three examinations were performed in each eye. One eye in each child was randomized for analyses of normal values. Findings in 54 eyes were evaluated. Mean values of RNFL thickness were calculated. Coefficients of variance and intraclass correlations were calculated. The correlation between right and left eyes and the limits of difference were determined for both methods. Results: Mean RNFL thickness was 98.4 μm (standard deviation [SD] 7.88 μm) assessed with OCT and 213.0 μm (SD 54.0 μm) assessed with HRT. No correlations between age or gender and RNFL thickness were found. The coefficients of variance were 2.9% and 5.6% for OCT and HRT, respectively, and intraclass correlations were 0.85 and 0.88, respectively. The limits of difference between the two eyes ranged from ?9 μm to 9 μm with OCT and from ?109 μm to 87 μm with HRT. Conclusions: Both OCT and HRT can be used in children aged 5–16 years, but OCT provides less variability in determinations of RNFL thickness, both in repeated examinations of the same eye and in comparisons between the two eyes. The present study provides values for normal RNFL thickness in healthy children which can be used to make comparisons with values in children with optic nerve diseases.     

The optic nerve head assessed with HRT in 5–16‐year‐old normal children: normal values,repeatability and interocular difference

Purpose: To investigate the normal values, repeatability and interocular difference of the optic nerve head, using Heidelberg retina tomography (HRT), in 5–16‐year‐old full‐term children with normal birth weights. Methods: Fifty‐six children with normal visual acuity and refraction were examined with HRT‐II/III. Three examinations were performed on each eye. One eye was randomized for analyses of normal values and repeatability, and 54 eyes could be evaluated. The coefficient of variance and the intraclass correlation (ICC) were calculated, and the ISNT rule was noted. The correlation between right and left eyes and the limits of difference were determined in 50 pair of eyes. Results: The mean values of disc and rim areas were 2.16 (SD 0.47) and 1.75 (SD 0.39) mm² respectively. The coefficients of variance varied between optic nerve parameters from 1.8% to 21%, and the ICCs were >0.88. All parameters except retinal nerve fibre layer thickness correlated with the disc area. The ISNT rule was fulfilled in 56% of the eyes. The interocular difference was large but not statistically significant. Conclusion: We conclude that HRT can be used in children between 5 and 16 years of age, and normal values presented in the study can be used for comparison of children with optic nerve diseases. Because the assessment of rim area varied the least, it may be the parameter to use for follow‐up. The normal large interocular difference should be taken into account when comparing eyes in the individual child.     

Repeatability in and interchangeability between the macular and the fast macular thickness map protocols: a study on normal eyes with Stratus optical coherence tomography

Purpose: To collect a normal material and to compare the macular and the fast macular thickness map protocols regarding normal values and repeatability. Methods: Sixty‐seven individuals underwent three repeated scans with the macular thickness protocol; 45 of them also had three scans with the fast thickness protocol in Stratus optical coherence tomography (OCT). The maps were divided into nine ETDRS fields, where thickness values were presented. The repeatability was calculated as intraclass correlation coefficient (ICC), coefficient of variance (CV) and coefficient of repeatability (CR). For comparison between the two protocols, limits of agreement were determined according to Bland–Altman. Results: Normal values for the two protocols were very close. Repeatability was high. ICC for all areas was 0.92–0.98. CV was less than 1% and CR was 6–8 μm for both protocols, with the exception of the fovea in the fast protocol (where CV was 1.44% and CR 12.4 μm). Limits of agreement between the two protocols were less than 10 μm as a rule. Conclusion: Normal values for the protocols are equal and they both have excellent repeatability. The fast macular map is a good alternative with the possible exception of the fovea, where variation is twice that of the macular thickness map.     

长扫描深度谱域OCT测量圆锥角膜患者全角膜厚度的重复性和再现性

目的探讨长扫描深度谱域OCT（UL-OCT）N4量圆锥角膜患者的全角膜三维厚度分布的重复性与再现性。方法前瞻性研究。选取圆锥角膜患者10例（10眼）,使用自行搭建的UL-OCT获得角膜的横断面图像．采用以角膜顶点为中心进行均等放射状B型扫描获取i维图像。通过全自动分割算法获取10mm直径范围角膜厚度分布图,并将测量结果与Pentacam三维眼前节分析诊断系统进行对比。2个仪器的重复性与再现性通过重复性系数与再现性系数（CoR）、组内相关系数（ICC）和变异系数（CV）进行比较。2个仪器的一致性通过配对t检验和Bland-Ahman方法进行分析。结果对于圆锥角膜患者,UL-OCT测量值的重复性系数为3．43～4．31μm,再现性系数为3．58～8．10μm。重复性和再现性的组内相关系数分别为0．998和0．995以上。Pentacam测量值的重复性系数为8．63～14．30μm,再现性系数为14．59～19．17μm。重复性和再现性的组内相关系数分别为0．997和0．994以上。UL-OCT系统测量的角膜厚度在中央区、旁中央区、过渡区、周围区分别为（468．9±38．6）μm、（482．5±48．6）μm、（515．5±57．0）μm、（588．0±52．5）μm。Pentacam系统测量的各区角膜厚度分别为（500．9＋50．0）μm、（533．9＋49．7）μm、（587．9±60．6）μm、（635．3±62．0）μm。Bland-Altman分析角膜厚度测量结果显示,2种仪器测量结果差值的95％一致性界限在中央区、旁中央区、过渡区分别为-44．49～108．59μm、-7．47～110．23μm、-13．21～131．68μm。结论在测量圆锥角膜患者全角膜厚度时,与Pentacam系统相比,UL-OCT系统具有更好的重复性和再现性。UL-OCT系统与Pentacam系统得到的角膜厚度测量结果存在差异,因此2种仪器在临床应用时不可互换。     

Measurement of central corneal thickness by high‐resolution Scheimpflug imaging,Fourier‐domain optical coherence tomography and ultrasound pachymetry

Purpose: To compare the repeatability and reproducibility of central corneal thickness (CCT) measurements by high‐resolution (HR) rotating Scheimpflug imaging and Fourier‐domain optical coherence tomography (FD‐OCT). CCT measurements were compared to those determined by ultrasound pachymetry (UP). Methods: In 35 healthy eyes, intra‐observer repeatability for HR Scheimpflug (Pentacam) and FD‐OCT (RTVue) systems was determined in consecutive images taken by an observer in the shortest time possible. Imaging was repeated again by a second observer to evaluate inter‐observer reproducibility. The CCT measurements were compared among Scheimpflug, FD‐OCT and UP images. Results: Mean coefficients of repeatability were 0.48% for Scheimpflug and 0.26% for FD‐OCT. For Scheimpflug, the coefficient of inter‐operator reproducibility was 0.87%. For FD‐OCT, the coefficient of inter‐operator reproducibility was 0.45%. The CCT measurements by Scheimpflug, OCT and UP images were (mean ± standard deviation) 521.7 ± 27.6 μm, 510.8 ± 28.6 μm and 516.5 ± 27.6 μm, respectively. The differences between instruments were statistically significant. The 95% limits of agreement in CCT were ?0.7 to 22.5 μm for Pentacam‐OCT, ?13.4 to 24.0 μm for Pentacam‐UP and ?26.7 to 15.4 μm for OCT‐UP. There was a high degree of correlation between CCT measured by all 3 methods. Conclusion: Noncontact measurements of CCT with HR Scheimpflug and FD‐OCT systems yielded excellent repeatability and reproducibility and can be used interchangeably. Although both devices were comparable with UP; in clinical practice, the measurements acquired by optical modalities are not directly interchangeable with UP measurements.     

Helvacioglu reproducibility index:a new algorithm to evaluate the effects of misalignments on the measurements of retinal nerve fiber layer by spectral-domain OCT

AIM:To evaluate the effect of misalignment on the measurements of retinal nerve fiber layer (RNFL) by spectral-domain optical coherence tomography (OCT).METHODS:A total of 42 eyes from 21 healthy young subjects underwent RNFL measurements with RTVue spectral-domain OCT (Optovue Inc., Fremont, California, USA). Two baseline measurements with perfectly aligned central circle to the borders of the optic nerve and four misaligned measurements which were misaligned towards to four quadrants were taken. The differences in RNFL between the baseline and misaligned measurements were analyzed with a new algorithm called Helvacioglu reproducibility index (HRI) which is designed to measure the reproducibility of the scans by evaluating the RNFL changes in the four main quadrants.RESULTS:The average RNFL scores of the first two baseline measurements have good correlation (c=0.930) and good reproducibility scores (0.15±0.07). Superior misaligned measurements had significantly lower superior quadrant score and higher inferior quadrant score, similar nasal and little higher temporal scores (P1, P2<0.001, P3=0.553, P4=0.001). Inferior misaligned measurements had significantly higher superior quadrant score and lower inferior quadrant score with similar temporal and little lower nasal scores (P1, P2<0.001, P3=0.315, P4=0.016). Nasal misaligned measurements had significantly higher temporal quadrant score and lower nasal quadrant score with little lower superior and inferior scores (P1, P2, P4<0.001, P3=0.005). Temporal misaligned measurements had significantly higher nasal quadrant score and lower temporal quadrant score with similar superior and little higher inferior scores (P1, P2<0.001, P3=0.943, P4=0.001).CONCLUSION:Good alignment of the central circle to the borders of optic nerve is crucial to have correct and repeatable RNFL measurements. Misalignment to a quadrant resulted in falsely low readings at that quadrant and falsely high readings at the opposite quadrant.     

频域OCT对正常中青年人黄斑区视网膜厚度的测量研究

目的研究频域Cirrus HD-OCT测量中青年人黄斑区视网膜厚度正常值。设计横断面研究。研究对象18～36岁的正常人98例196眼。方法用Cirrus HD-OCT的512×128及200×200两种扫描模式对受试者双眼黄斑区进行检测。主要指标黄斑中心区视网膜厚度,黄斑区视网膜体积,黄斑区平均视网膜厚度。结果采用512×128扫描模式,黄斑中心区视网膜厚度为(242.41±20.02)μm,黄斑区视网膜体积为(10.01±0.60)mm3,黄斑区平均视网膜厚度为(280.71±12.41)μm。九个分区视网膜平均厚度之间除了内环上方与内环鼻侧及内环颞侧与外环鼻侧之间无显著性差异外,其余各区之间均有显著性差异。左右眼之间差异无统计学意义。采用512×128及200×200两种扫描模式所测结果差异无统计学意义。结论频域Cirrus HD-OCT测量的正常中青年人黄斑区视网膜厚度较文献报告的Stratus OCT约厚50μm,在临床上进行比较时应注意仪器差异。     

自动化分割算法分析RTVue100 OCT黄斑区视网膜各层厚度的重复性和再现性研究

背景视网膜各层厚度的检测和评估对多种眼科疾病的诊断、治疗及预后的监测至关重要,频域光学相干断层扫描（OCT）是目前常用的测量工具。以往的测量方法采用软件分析法,但关于视网膜自动分层软件可靠性的研究较少。目的评估自动化分割算法分析RTVue100 OCT测量黄斑区视网膜各层厚度的重复性和再现性。方法采用横断面研究设计,纳入正常受试者18人18眼,用RTVue100 OCT拍摄受试者右眼以黄斑中心凹为中心6mm扫描区的视网膜各层厚度图像,采用自动化分割算法将视网膜图像分割成神经纤维层（RNFL）、神经节细胞层和内丛状层（GCL＋IPL）、内核层（INL）、外丛状层（OPL）、外核层（ONL）、光感受器内节（IS）、光感受器外节（OS）、视网膜色素上皮（RPE）层,并用Matlab软件进行分析,通过将自动探测得到的相邻两条边界相对应的位置相减获得结果。每个受检眼先由一位操作者连续拍摄2次,然后由另一位操作者拍摄1次,采用组内相关系数（ICC）和重复性系数（COR）分析测得结果的重复性和再现性。结果RTVue100 OCT测量得到水平方向视网膜全层厚度为（303．22±14．10）μm,垂直方向为（306．68±13．32）μm。视网膜各层结构中,最厚的为GCL＋IPL以及ONL。同一检查者测量2次的重复性结果和不同检查者之间的再现性结果均表明,无论在水平方向还是在垂直方向,OPL、IS和OS的ICC和COR均〈0．60,而RNFL、GCL＋IPL、INL、ONL和RPE层的ICC和COR均〉0．70。结论自动化分割算法分析RTVue OCT图像是一种可靠的工具,可提供重复性的OCT视网膜厚度资料,有利于视网膜疾病的诊断和监测。     

Measurement of retinal thickness in macular region of high myopic eyes using spectral domain OCT

AIM:To investigate the changes of retinal thickness in macula of high myopic eyes using spectral domain optical coherence tomography (OCT).METHODS: Middle-aged and young myopic patients were divided into three groups according to their refractive error/axial length:low and medium myopia group (LMMG), high myopia group (HMG) and super high myopia group (SHMG). Cirrus HD-OCT was used to evaluate total average macular thickness, central subfield thickness, inner/outer macular thickness and macular volume. The differences among experimental groups were analyzed by one-factor analysis of variance. Associations between macular thickness and refractive error/axial length were analyzed by Pearson correlation analysis.RESULTS: There was no significant difference in age among the three groups (P=0.2789). The mean refraction error in the LMMG, HMG, and SHMG groups was -2.49±1.38D, -8.53±1.95D and -13.88±1.76D, respectively (P＜0.001). The central subfield thickness of three groups was 244.56±12.19μm, 254.33±11.61μm and 261.75±11.83μm, respectively, and there were statistically significance between random two groups. The total average macular thickness, inner/outer macular thickness, and macular volume decreased with increased myopia/axial length. Average foveal thickness had negative correlations with refractive error (P＜0.001), and positive correlations with axial length. The inferior and temporal inner macular thickness, all the quadrants of outer ring, total average macular thickness and macular volume featured positive correlations with refractive error, and negative correlations with axial length. Average foveal thickness, superior and temporal inner macular thicknesses, and temporal outer macular thickness was lower in females compared to males.CONCLUSION:With an increase in myopia degree/axial length, the average foveal thickness increased and the inner/outer macular thickness decreased. Females featured thicker average foveal thickness, and thinner macular thickness compared to males.     

频域OCT对正常人和青光眼光感受器细胞层厚度的检测

背景青光眼以视网膜内层的神经节细胞丢失为主要病理特征,但其是否累及视网膜外层尚有争议。部分研究认为青光眼将导致视网膜外层（光感受器）功能的异常,而病理学研究得出了不同的结论。目的用频域OCT测量正常人和青光眼患者光感受器细胞层的厚度,探讨青光眼对光感受器细胞层厚度的影响。方法采用病例对照研究。用频域OCT（SDOCT）对正常人38例38眼和青光眼患者48例48眼的黄斑区进行扫描,由一位检测者采用Sigma图像分析软件盲法测量黄斑中心凹和旁中心凹处（中心凹外1．5mm）视网膜光感受器层的厚度。同时采用时域OCT（Stratus OCT）测量所有检测眼的视盘周围视网膜神经纤维层（RNFL）厚度,比较正常组和青光眼组光感受器细胞核层的平均厚度,分析光感受器细胞层厚度与RNFL厚度的关系。结果正常组和青光眼组在黄斑中心凹光感受器细胞核层厚度分别是（96．7±10．7）μm、（103．7±13．3）μm,差异有统计学意义（P=0．011）;中心凹光感受器内节和外节层厚度分别是（59．3±5．5）μm、（59．5±5．5）μm,差异无统计学意义（P=0．890）。正常组和青光眼组在中心凹外3mm处光感受器细胞核层厚度分别是（70．9±14．0）μm、（68．7±10．7）μm,光感受器内节和外节层厚度分别为（45．2±6．4）μm,（43．6±5．5）μm,差异均无统计学意义（P=0．410,P=0．228）。黄斑中心凹处光感受器细胞核层厚度和RNFL厚度两者有二元线性关系（γ=-0．019X。＋2．73X＋10．34,R^2=0．211,P=0．005）。结论青光眼的黄斑中心凹光感受器细胞核层显著增厚,并随病程的变化而改变。     

频域光学相干断层扫描在视网膜神经纤维层厚度测量中的应用

目的应用频域光学相干断层扫描（OCT）测量非青光眼受试者和青光眼患者的视盘周视网膜神经纤维层（RNFL）厚度,并对测量结果进行重复性检验。方法非青光眼受试者和青光眼患者各30例纳入研究,随机选取受试者一侧眼的数据进行统计分析。应用Spectralis OCT对每位受试者进行视盘周RNFL厚度测量,应用“随诊”模式进行3次扫描。计算出受试者内部标准筹（Sw）、变异系数（CV）和同类相关系数（ICC）,以评价该仪器测量的可重复性。应用Spearman秩相关系数分析评估每位受试者RNFL厚度平均数值与其3次测量的标准差之间的天系。结果非青光眼受试者的CV数值范围为1．44％（全周厚度平均值）～2．58％（颞侧象限）,青光眼患者的CV为1．73％（全周）～3．24％（颞侧象限）;非青光眼受试者的ICC数值范围为0．977（颞侧象限）～0．990（鼻下45。扇形区）,青光眼患者的ICC数值范围为0．981（颞侧象限）～0．997（下方象限）;非青光眼受试者的Sw为1．33μm（全周）～2．36μm（颞上45°扇形区）,青光眼患者的Sw为1．13μm（全周）～2．26μm（鼻上45。扇形区）;RNFL厚度数值与测量变异性间无明显相关性（P〉0．05）。结论高速扫描和眼跟踪系统使Spectralis OCT在测量非青光眼受试者和青光眼患者的视盘周RNFL厚度均有良好的可重复性,是青光眼长期随诊中对于其结构性损害可信赖的影像学检查技术。     

Macular thickness and volume of myopic eyes measured using spectral‐domain optical coherence tomography

Purpose: The aim was to evaluate macular thickness and volume of young myopic eyes measured using Cirrus HD spectral‐domain optical coherence tomography (Cirrus HD‐OCT; Carl Zeiss Meditec, Dublin, CA, USA). Methods: Three hundred and thirty‐six eyes of 336 healthy young subjects (aged 19 to 25) with various degrees of refractive error and axial length were recruited. Average macular thickness, foveal thickness, inner/outer macular thickness and macular volume were measured using Cirrus HD‐OCT. The association between refractive error/axial length and retinal thickness/volume was analysed. Results: The mean average macular thickness, foveal thickness, inner/outer macular thickness and macular volume were 280.7 ± 10.9 µm, 258.1 ± 18.4 µm, 320.6 ± 12.7/277.3 ± 12.3 µm and 10.1 ± 0.4 mm³, respectively. Average macular thickness, inner/outer macular thickness and macular volume decreased and foveal thickness increased as the degree of myopia/axial length increased (p‐values less than 0.01). The correlation between axial length and macular measurements remained significant when refractive error was controlled (p ≤ 0.017); however, when axial length was controlled, the association between refractive error and macular thickness/volume was no more significant (p ≥ 0.084). Conclusions: In healthy young myopic eyes, thinner macular thickness, lower macular volume and thicker foveal thickness were associated with longer axial length.     

Macular choroidal thickness in Chinese preschool children: decrease with axial length but no evident change with age

AIM: To explore the distribution pattern of macular choroidal thickness (ChT) and its association with age as well as refractive status in Chinese preschoolers. METHODS: School-based, cross-sectional study. A total of 550 healthy preschool children aged 3 to 6 years old from 6 kindergartens were enrolled. Comprehensive ocular examinations, including measurement of visual acuity, axial length, intraocular pressure and slit-lamp examination before cycloplegia, as well as refraction measurement and swept-source optical coherence tomography (SS-OCT) examination after cycloplegia, were performed. The macular ChT in each sector of the ETDRS grid was measured by the built-in software of SS-OCT. RESULTS: The mean central ChT of the participants was 312±59 μm. The mean axial length and spherical equivalent refraction were 22.36±0.72 mm and 1.51±0.83 D, respectively. Axial length increased with age (P<0.001), while the spherical equivalent refraction was similar among different age groups. Similarly, no significant difference was observed in ChT in all sectors among different age groups (all P>0.05). The central ChT of 3-4, 5 and 6 years old children was 314±59 μm, 312±60 μm and 312±59 μm, respectively (P=0.920). No difference was observed in ChT in most of the sectors between genders. No statistical significant difference was observed among different refractive groups (all P>0.05), though the ChT of each sector seemed to be smaller in myopic children. Axial length and weight were the independent factors of central ChT. Children with longer axial length (β=-21.184, P<0.001) and smaller weight (β=1.502, P=0.041) tended to have thinner choroid. CONCLUSION: In preschool children, the ChT remains relatively stable with age, while a negative association between ChT and axial length existed. This will be helpful to elucidate the characteristics of ChT during the early refractive development.     

Retinal nerve fiber layer and optic disc measurements by spectral domain OCT: normative values and associations in young adults

Purpose

To determine normative values and associations of retinal nerve fiber layer (RNFL) and optic disc parameters in normal eyes measured by spectral domain optical coherence tomography (OCT).

Methods

In a population-based setting, 1521 young adults were examined as part of the Sydney Adolescent Vascular and Eye Study (SAVES). Their mean age was 17.3±0.6 years. RNFL and optic disc parameter measurements were made using Cirrus HD-OCT 4000.

Results

The average RNFL was found to be 99.4±9.6 μm. RNFL thickness was least for the temporal quadrant (69.9±11.2 μm), followed by the nasal (74.3±12.8 μm), superior (124.7±15.7 μm) and inferior (128.8±17.1 μm) quadrants. The mean disc area in this population was 1.98±0.38 mm² with a mean rim area of 1.50±0.30 mm² and a mean cup/disc ratio of 0.44±0.18. Multivariate-adjusted RNFL thickness was marginally greater in East Asian than in white participants (100.1 μm vs 99.5 μm; P=0.0005). The RNFL was thinner with greater axial length (P<0.0001), less positive spherical equivalent refractions (P<0.0001), smaller disc area and rim area (P<0.0001).

Conclusion

This study documents normative values for the RNFL and optic disc measured using Cirrus HD-OCT in young adults. The values and associations reported in this study can inform clinicians on the normal variation in RNFL and optic disc parameters.     

Multimodal imaging in acute retinal ischemia: spectral domain OCT, OCT-angiography and fundus autofluorescence

AIM: To describe retinal findings of various imaging modalities in acute retinal ischemia. METHODS: Fluorescein angiography (FA), spectral domain optical coherence tomography (SD-OCT), OCT-angiography (OCT-A) and fundus autofluorescence (FAF) images of 13 patients (mean age 64y, range 28-86y) with acute retinal ischemia were evaluated. Six suffered from branch arterial occlusion, 2 had a central retinal artery occlusion, 2 had a combined arteriovenous occlusions, 1 patient had a retrobulbar arterial compression by an orbital haemangioma and 2 patients showed an ocular ischemic syndrome. RESULTS: All patients showed increased reflectivity and thickening of the ischemic retinal tissue. In 10 out of 13 patients SD-OCT revealed an additional highly reflective band located within or above the outer plexiform layer. Morphological characteristics were a decreasing intensity with distance from the fovea, partially segmental occurrence and manifestation limited in time. OCT-A showed a loss of flow signal in the superficial and deep capillary plexus at the affected areas. Reduced flow signal was detected underneath the regions with retinal edema. FAF showed areas of altered signal intensity at the posterior pole. The regions of decreased FAF signal corresponded to peri-venous regions. CONCLUSION: Multimodal imaging modalities in retinal ischemia yield characteristic findings and valuable diagnostic information. Conventional OCT identifies hyperreflectivity and thickening and a mid-retinal hyperreflective band is frequently observed. OCT-A examination reveals demarcation of the ischemic retinal area on the vascular level. FAF shows decreased fluorescence signal in areas of retinal edema often corresponding to peri-venous regions.