Retinal nerve fibre layer thickness profile in normal eyes using third-generation optical coherence tomography

AIMS: To establish four normal retinal nerve fibre layer (RNFL) thickness radial profiles based on third-generation optical coherence tomography (OCT) and to compare them with previously reported histologic measurements. METHODS: A total of 20 normal eyes were studied. A circular scan was adjusted to the size of the optic disc and three scans were performed with this radius and every 200 microm thereafter, up to a distance of 1400 microm. Four different radial sections (superotemporal, superonasal, inferonasal, and inferotemporal) were studied to establish RNFL thickness OCT profiles. Additionally, two radial scans orientated at 45 and 135 degrees crossing the optic disc centre were performed in six of 20 eyes, and RNFL thickness was measured at disc margin. RESULTS: Quadrant location and distance from disc margin interaction in RNFL thickness was statistically significant (P<0.001). The RNFL thickness decreased (P<0.001) as the distance from the disc margin increased for all sections. The measurements automatically generated by the OCT built-in software were thinner (P<0.001) than histologic ones close to the disc margin. CONCLUSIONS: Four normal OCT RNFL profiles were established and compared with histological data obtained from the same area. RNFL measurements assessed by OCT 3 were significantly thinner close to the optic disc margin.     

Peripapillary retinal nerve fiber layer thickness in normal Japanese eyes measured with optical coherence tomography

Purpose  

To measure peripapillary retinal nerve fiber layer (RNFL) thickness in healthy Japanese individuals using optical coherence tomography (OCT).     

Retinal nerve fibre layer thickness measurements in normal Indian population by optical coherence tomography

PURPOSE: To obtain retinal nerve fibre layer thickness measurements by optical coherence tomography (OCT) in normal Indian population. MATERIALS AND METHODS: Total of 118 randomly selected eyes of 118 normal Indian subjects of both sex and various age groups underwent retinal nerve fiber layer thickness analysis by Stratus OCT 3000 V 4.0.1. The results were evaluated and compared to determine the normal retinal nerve fiber layer thickness measurements and its variations with sex and age. RESULTS: Mean +/- standard deviation retinal nerve fiber layer thickness for various quadrants of superior, inferior, nasal, temporal and along the entire circumference around the optic nerve head were 138.2 +/- 21.74, 129.1 +/- 25.67, 85.71 +/- 21, 66.38 +/- 17.37 and 104.8 +/- 38.81 microm, respectively. There was no significant difference in the measurements between males and females and no significant correlation with respect to age. CONCLUSION: Our results provide the normal retinal nerve fiber layer thickness measurements and its variations with age and sex in Indian population.     

Quantification of photoreceptor layer thickness in normal eyes using optical coherence tomography

OBJECTIVE: To demonstrate the ability to segment and analyze individual intraretinal layers, including the outer retinal complex (ORC; outer nuclear layer and inner and outer segments of the photoreceptor cells), in healthy eyes using images acquired from the latest commercially available optical coherence tomography (OCT) system (StratusOCT; Carl Zeiss Meditec, Inc., Dublin, CA) and from the ultrahigh resolution OCT (UHR-OCT) prototype. METHODS: Thirty-seven eyes from 37 healthy subjects underwent complete ophthalmologic examination using StratusOCT and UHR-OCT. ORC was identified and measured using a segmentation algorithm. RESULTS: For StratusOCT, mean weighted ORC thickness +/- SD was 91.1 +/- 7.9 microm, and mean weighted total retinal thickness +/- SD was determined to be 258.9 +/- 10.1 microm. For UHR-OCT, mean weighted ORC thickness +/- SD was 96.4 +/- 6.3 microm, and mean weighted total retinal thickness +/- SD was determined to be 263.4 +/- 9.2 mum. There was a higher rate of algorithm failure with UHR-OCT images. CONCLUSIONS: Photoreceptor layer thickness can be calculated by measuring ORC on OCT images using a macular segmentation algorithm. ORC values may serve as a useful objective parameter in determining the efficacy of various therapeutic modalities that target the photoreceptor layer in various diseases.     

Modelling the normal retinal nerve fibre layer thickness as measured by Stratus optical coherence tomography

Background The variation in retinal nerve fibre layer thickness (RNFLT) as measured by Stratus optical coherence tomography (OCT) in healthy subjects may be reduced when the effect on RNFLT measurements of factors other than disease is corrected for, and this may improve the diagnostic accuracy in glaucoma. With this perspective we evaluated the isolated and combined effects of factors potentially affecting the Stratus OCT RNFLT measurements in healthy subjects.Methods We included 178 healthy eyes of 178 subjects between 20 and 80 years of age. Participants underwent an extensive eye examination. Stratus OCT RNFLT was measured by three standard protocols, two with high and one with standard image resolution. Effects on RNFLT of age, gender, refractive error, axial length, lens nuclear colour and opalescence, intra-ocular pressure (IOP), and optic disc size were examined by univariate and multivariate analyses.Results Age, refractive error, axial length, and lens nuclear colour and opalescence affected RNFLT in univariate analyses, whereas gender, IOP, and optic disc size had no significant effect. In multivariate analyses only age in combination with refractive error, or with axial length, was significant and explained 14.7–17.6% (R ²) of the total variation of RNFLT, approximately 50% more than age alone. RNFLT decreased by 2.6–2.9 μm per increasing decade of age and increased by 1.5–1.8 μm per more positive diopter of spherical equivalent using full-circle measurements of the three standard protocols. These effects varied between measurement sectors.Conclusions RNFLT as measured by Stratus OCT standard protocols was significantly affected by age and refractive status. The effect on global RNFLT of a difference in refractive error of 10 diopters corresponded to the effect of a difference in age of 60 years. Theoretically, the effect of refractive status may be explained by artefacts of RNFLT measurement circle placement. The results suggest that the diagnostic accuracy of Stratus OCT may be improved by considering refractive status in addition to age when RNFLT is measured. For this purpose spherical equivalent seems as effective as axial length.     

Asymmetry analysis of the retinal nerve fiber layer thickness in normal eyes using optical coherence tomography

PURPOSE: To investigate the asymmetry of the retinal nerve fiber layer thickness (RNFLT) with respect to the horizontal and vertical meridian and between the right and left eye in normal subjects. METHODS: The RNFLT was measured in 121 normal volunteers by optical coherence tomography (OCT). The RNFLT was analyzed by dividing the circle scanning area (diameter 3.4 mm) around the optic disc into 4 quadrants and 12 sectors. RESULTS: There was a significant difference between the RNFLT of the nasal and temporal quadrant in individual eyes. There was a significant difference between the RNFLT of corresponding sectors with respect to the vertical or horizontal meridian in individual eyes. The nasal and temporal RNFLTs were asymmetrical between the right and left eye in the quadrant and sector analysis. The RNFLT of the nasal and temporal quadrant was thicker in the right eye. The nasal and inferior RNFLT measured by OCT had a significant correlation with degree of refractive error. CONCLUSIONS: In normal subjects without significant anisometropia, there was significant asymmetry of the RNFLT for each eye as well as between the right and left eye.     

光学相干断层成像术检测5～18岁国人正常眼视网膜神经纤维层厚度

目的:建立5～18岁国人正常眼经光学相干断层成像术(OCT)检测的视盘周围视网膜神经纤维层(RNFL)厚度参考值范围;研究RNFL厚度各相关参数与眼别、性别的关系及其各参数的变异程度。方法:对75例5～18岁正常人135只正常眼,应用光学相干断层成像仪StratusOCTTM3000,采用RN-FL3.4程序对视盘为中心直径3.4mm的RNFL进行检测。资料的统计学处理应用SPSS10.0软件。结果:5～18岁国人正常眼1,2,～12各钟点位RN-FL厚度(μm)为134.43±27.62,88.74±21.78,57.82±11.72,76.47±16.57,120.52±22.53,154.48±26.19,159.34±20.68,88.01±17.10,66.28±9.96,97.70±16.17,148.81±19.29,147.00±25.77;上侧(Savg),鼻侧(Navg),下侧(Iavg),颞侧(Tavg)各象限厚度(μm)分别为143.42±16.41,74.36±13.75,144.75±16.46,83.96±12.12;全周平均厚度(Avg)111.63±9.58μm。不同眼别的1,2,8,10,11,12,Savg,Navg,Tavg,Smax/Tavg,Imax/Tavg,Smax/Navg组的均数间差异有显著性(｜t｜=2.490￣3.765,P=0.000￣0.016,P<0.05。不同性别相同眼别间,大部分对应的RNFL厚度相关参数间的差异无显著性(t=-1.702￣1.922,P=0.060￣0.894,P>0.05)。④各参数组变异系数(%):1,2,～12各钟点位依次为20.55,24.54,20.26,21.66,18.70,16.95,12.98,19.43,15.02,16.55,12.96,17.53;按Savg,Navg,Iavg,Tavg,Avg依次为11.44,18.50,11.37,14.53,8.58。结论:OCT检测5～18岁国人正常眼RNFL厚度钟点位中以6,7,11,12点较厚;Savg,Iavg接近并大于Tavg,Navg。不同眼别的RNFL厚度部分参数间差异有显著性,推测该差异与视网膜血管的管径大小及走行的不同有关。临床评估RNFL厚度检测结果时应考虑各参数变异程度不同的因素。     

Asymmetries of the retinal nerve fibre layer thickness in normal eyes

AIMS: To investigate the variation in the retinal nerve fibre layer thickness in detail in normal eyes with a scanning laser polarimeter. METHODS: The retinal nerve fibre layer thickness (RNFLT) was measured in 94 normal volunteers with a scanning laser polarimeter. The mean RNFLT around a 10 pixel-wide ellipse located concentrically with the disc of 1.5 disc diameters was calculated for 16 sectors each of 22.5 degrees. The symmetry of the RNFLT distribution with respect to the horizontal midline for individual eyes and to the vertical meridian for the two eyes was examined. RESULTS: The RNFLT was thicker on the inferior side than on the superior side for the temporal four pairs of 22.5 degrees sectors, and the differences were significant in two of the four temporal pairs (p<0.007). The RNFLT was thicker in the superior than in the inferior side for the nasal four pairs of the sectors, and the differences were significant in three of the four nasal pairs (p<0.04). The mean RNFLT was significantly thicker in the right eyes than in the left eyes in the four temporal sectors (p<0.02), and significantly thicker in the left eyes than in the right eyes in the inferior two nasal sectors (p<0.01). CONCLUSIONS: Asymmetries of the RNFLT in normal eyes with respect to the horizontal midline and to the vertical meridian for the two eyes were found. These asymmetries should be considered when retinal nerve fibre layer loss is evaluated during the course of a disease process.     

Estimating retinal nerve fiber layer thickness in normal schoolchildren with spectral-domain optical coherence tomography

Purpose  

To measure the peripapillary retinal nerve fiber layer (RNFL) thickness in normal schoolchildren with spectral domain optical coherence tomography (SD-OCT), and to evaluate the effects of age, spherical equivalent (SE) refraction, OCT signal strength, and cycloplegic treatment on RNFL thickness.     

Reproducibility of peripapillary retinal nerve fiber layer thickness with spectral domain cirrus high-definition optical coherence tomography in normal eyes

Purpose  

To assess the reproducibility of the new spectral domain Cirrus high-definition optical coherence tomography (HD-OCT; Carl Zeiss Meditec, Dublin, CA, USA) for analysis of peripapillary retinal nerve fiber layer (RNFL) thickness in healthy eyes.     

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.     

正常人视盘、视杯形态及盘周神经纤维层光学相干断层定量检测

目的:观察光学相干断层扫描仪检测正常人视盘、视杯形态及盘周视网膜神经纤维层厚度.方法:应用Carl Zeiss公司Humphrey2000型光学相干断层扫描仪检查系统对80例单侧眼病患者的80只正常对侧眼进行视盘"十字交叉"和"环形"扫描,分别测量视盘、视杯的直径,视杯深度,以及盘周视网膜神经纤维层厚度,计算杯盘比值及面积,统计各参数的平均值.结果:用视盘横纵扫描方法测量结果为:视盘纵扫直径为1.60±0.22mm,横扫直径为1.40±0.15mm,平均直径为1,50±0.22mm;视盘扫描平均面积为1.77±0.53mm2.视杯纵扫直径为0.54±0.22mm,视杯横扫直径为0.52±0.24mm,平均直径为0.54±0.23mm;视杯扫描平均面积为0.26±0.20mm2;正常人杯盘直径比纵扫为0.34±0.13,杯盘直径比横扫为0.38±0.15,平均为0.36±0.14;杯盘面积比平均为0.15±0.11.视杯深度纵扫为0.31±0.14mm,横扫为0.27±0.14mm,平均为0.29±0.14mm.用视盘周围环扫方法测量的盘周神经纤维层厚度结果:颞侧为95.57±17.63μm,上方为144.17±18.98μm,鼻侧为99.00±28.13μm,下方为155.53±18.65μm.结论:光学相干断层检测能做出视盘及视杯的定量测量和分析,得到的正常值范围可作为前部缺血性视神经病变、青光眼性视神经损害等视神经疾病临床观察的参考.     

Evaluation of retinal nerve fiber layer thickness in the area of apparently normal hemifield in glaucomatous eyes with optical coherence tomography

PURPOSE: The authors investigated the correlation between visual field defects detected by automated perimetry and the thickness of the retinal nerve fiber layer measured with optical coherence tomography, and examined whether there is a decrease in retinal nerve fiber layer thickness in the apparently normal hemifield of glaucomatous eyes. PATIENTS AND METHODS: Forty-one patients with glaucoma and 41 normal control subjects were included in this study. Statistical correlations between the sum of the total deviation of 37 stimuli of each hemifield and the ratio of decrease in retinal nerve fiber layer thickness were evaluated. The statistical difference between the retinal nerve fiber layer thickness of the apparently normal hemifield in glaucomatous eyes and that of the corresponding hemifield in normal subjects was also evaluated. RESULTS: There was a statistically significant correlation in the sum of the total deviation and retinal nerve fiber layer thickness decrease ratio (superior hemifield, P = 0.001; inferior hemifield, P = 0.003). There was no significant decrease in retinal nerve fiber layer thickness in the area that corresponded to the normal visual field in the hemifield defect with respect to the horizontal meridian in glaucomatous eyes (superior side, P = 0.148; inferior side, P = 0.341). CONCLUSIONS: Optical coherence tomography was capable of demonstrating and measuring retinal nerve fiber layer abnormalities. No changes in the retinal nerve fiber layer thickness of the apparently normal hemifield were observed in glaucomatous eyes.     

Retinal nerve fiber layer thickness in normal Indian pediatric population measured with optical coherence tomography

Purpose:

To measure the peripapillary retinal nerve fiber layer (RNFL) thickness in normal Indian pediatric population.

Subjects and Methods:

120 normal Indian children ages 5-17 years presenting to the Pediatric Clinic were included in this observational cross-sectional study. RNFL thickness was measured with stratus optical coherence tomography (OCT). Children with strabismus or amblyopia, with neurological, metabolic, vascular, or other disorders and those with abnormal optic discs were excluded. One eye of each subject was randomly selected for statistical analysis. The effect of age, refraction and gender on RNFL thickness was investigated statistically.

Result:

OCT measurements were obtained in 120 of 130 (92.3%) subjects. Mean age was 10.8 ± 3.24 years (range 5-17). Average RNFL thickness was (± SD) 106.11 ± 9.5 μm (range 82.26-146.25). The RNFL was thickest inferiorly (134.10 ± 16.16 μm) and superiorly (133.44 ± 15.50 μm), thinner nasally (84.26 ± 16.43 μm), and thinnest temporally (70.72 ± 14.80 μm). In univariate regression analysis, age had no statistical significant effect on RNFL thickness (P =0.7249) and refraction had a significant effect on RNFL thickness (P =0.0008).

Conclusion:

OCT can be used to measure RNFL thickness in children. Refraction had an effect on RNFL thickness. In normal children, variation in RNFL thickness is large. The normative data provided by this study may assist in identifying changes in RNFL thickness in Indian children.     

Macular thickness evaluation using the optical coherence tomography in normal Indian eyes

PURPOSE: To determine the normative values for macular thickness and volume by Optical Coherence Tomography (OCT 3) in healthy Indian subjects. METHODS: The macula of 170 consecutive, randomly selected normal subjects was imaged on OCT 3 in this cross-sectional study. OCT parameters of macular thickness were analysed with baseline variables including age, gender, axial length and refractive error. RESULTS: The average foveal thickness in the population under study was 149.16 +/- 21.15 micro. Macular thickness and volume parameters of OCT correlated significantly (Pearson's Correlation coefficient) with age (r=0.23, P<0.01), but not with gender, axial length and refraction. CONCLUSIONS: The macular thickness and volume parameters have a significant correlation with age. This normative database of macular thickness by OCT in Indian eyes may be a useful guideline for management and further research in diseases of the macula and glaucoma.