Optical coherence tomography measurement of macular and nerve fiber layer thickness in normal and glaucomatous human eyes

PURPOSE: To evaluate the hypothesis that macular thickness correlates with the diagnosis of glaucoma. DESIGN: Cross-sectional study. PARTICIPANTS: We studied 367 subjects (534 eyes), including 166 eyes of 109 normal subjects, 83 eyes of 58 glaucoma suspects, 196 eyes of 132 early glaucoma patients, and 89 eyes of 68 advanced glaucoma patients. METHODS: We used optical coherence tomography (OCT) to measure macular and nerve fiber layer (NFL) thickness and to analyze their correlation with each other and with glaucoma status. We used both the commercial and prototype OCT units and evaluated correspondence between measurements performed on the same eyes on the same days. MAIN OUTCOME MEASURE: Macular and NFL thickness as measured by OCT. RESULTS: All NFL parameters both in prototype and commercial OCT units were statistically significantly different comparing normal subjects and either early or advanced glaucoma (P < 0.001). Inner ring, outer ring, and mean macular thickness both in prototype and commercial OCT devices were found to be significantly different between normal subjects and advanced glaucomatous eyes (P < 0.001). The outer ring was the only macular parameter that could significantly differentiate between normal and early glaucoma with either the prototype or commercial OCT unit (P = 0.003, P = 0.008, respectively). The area under the receiver operator characteristic (AROC) curves comparing mean NFL thickness between normal and advanced glaucomatous eyes was 1.00 for both the prototype and commercial OCT devices for eyes scanned on both machines on the same day. The AROC comparing mean macular thickness in normal and advanced glaucomatous eyes scanned on both machines on the same day was 0.88 for the prototype OCT device and 0.80 for the commercial OCT. CONCLUSIONS: Both macular and NFL thickness as measured by OCT showed statistically significant correlations with glaucoma, although NFL thickness showed a stronger association than macular thickness. There was good correspondence between findings using both the prototype and commercial OCT units. Macular and NFL thickness measurements made with OCT may have usefulness in the clinical assessment of glaucoma.     

Macular and retinal nerve fiber layer analysis of normal and glaucomatous eyes in children using optical coherence tomography

PURPOSE: To evaluate macular and nerve fiber layer (NFL) thickness in normal and glaucomatous eyes of children 3 to 17 years old using optical coherence tomography (OCT-3). DESIGN: Observational cross-sectional study. METHODS: One hundred fifty-six eyes of 79 patients were enrolled in this institutional study. Fifty-two eyes (33.3%) met criteria for glaucoma and 104 (66.7%) were normal. There were 44 female (55.6%) and 35 male (44.3%) subjects whose ages ranged from 3 to 17 years old (mean 9.5 years, standard deviation 3.5 years, median 9 years). The OCT-3 (Carl Zeiss Meditec, Dublin, California) was used to obtain a fast macular thickness map as well as a fast retinal NFL map of each eye. Data from specific locations around the macula, as well as total macular volume, was analyzed. Similarly, the retinal NFL scan reports average NFL thickness from specific locations around the optic nerve. Data from the superior temporal and inferior temporal sections was analyzed. RESULTS: There was a statistically significant difference in macular thickness and NFL thickness when normal eyes were compared against those with glaucoma, in all quadrants studied (all P values 相似文献   

Reliability of nerve fiber layer thickness measurements using optical coherence tomography in normal and glaucomatous eyes

OBJECTIVE: To evaluate the reliability of nerve fiber layer (NFL) thickness measurements by optical coherence tomography (OCT) in normal and glaucomatous eyes. DESIGN: Prospective, comparative, observational case series and instrument validation study. PARTICIPANTS: Twenty-four glaucomatous patients were compared with 24 gender- and age-matched normal subjects. METHODS: Each individual underwent OCT measurements of NFL thickness. Five repetitions of a series of scans on five separate occasions within a 0.5-month period were performed. Each eye was scanned at three different nerve head programs (1.5 radius [R], R = 1.73 mm, 2.0 R). For each option (1.5 R, R = 1.73 mm, and 2.0R) and region (superior, inferior, temporal, nasal, and overall mean), variance components and intraclass correlation coefficients were determined using repeated measures regression. In these models, NFL thickness, as measured by OCT, was assumed to have three variance components: intersubject, intervisit (within-subject between-dates), and intravisit (within-subject within-date). The intraclass correlation coefficient (intersubject variance/total variance) was used as a measure of reliability. MAIN OUTCOME MEASURES: Measurements of NFL thickness using OCT were performed. RESULTS: Reliability values, as measured by intraclass correlation coefficients, resulted as follows: 1.5 R, 0.54/0.52 (normal/glaucoma); R = 1.73 mm, 0.50/0.50; 2.0 R, 0.49/0.50. CONCLUSIONS: Our results indicate that the recent commercially available OCT provides reliable NFL thickness measurements in both healthy and glaucomatous eyes with each circle radius tested. The greatest amount of variability can be attributed to intersubject differences.     

Comparison of three optical coherence tomography scanning areas for detection of glaucomatous damage

PURPOSE: Several cross-sectional studies have demonstrated the capability of optical coherence tomography (OCT) to detect glaucomatous changes. OCT enables posterior pole scanning of three regions: macula, peripapillary, and optic nerve head (ONH). This study compared the ability of each region to detect glaucomatous damage. DESIGN: Retrospective observational cross-sectional study. METHODS: The study included 37 normal (37 subjects) and 37 glaucomatous eyes (26 subjects) that had comprehensive ocular examination, reliable and reproducible Swedish interactive thresholding algorithm standard 24-2 perimetry, and Stratus OCT scanning of macula, peripapillary, and ONH regions on the same visit. Optical nerve head (ONH) appearance did not form part of the inclusion criteria. The main outcome measure, was area under receiver operating characteristic curves (AROCs) that was calculated for each scanning region for distinguishing between normal and glaucomatous eyes. RESULTS: The highest AROCs for distinguishing between groups were for ONH parameters (rim area = 0.97, horizontal integrated rim width = 0.96, vertical integrated rim area = 0.95) and peripapillary nerve fiber layer (NFL) thickness (0.94) followed by macular volume and thickness (both 0.80). A statistically significant difference existed in ONH and NFL AROCs when compared with macular AROCs (P < or = .007, for both) CONCLUSIONS: OCT ONH and NFL parameters provided similar discrimination capabilities between healthy eyes and those of glaucoma patients and superior discrimination capabilities when compared with macular parameters.     

Optical coherence tomography (OCT) macular and peripapillary retinal nerve fiber layer measurements and automated visual fields

PURPOSE: To investigate the structure-function relationship between optical coherence tomography (OCT) macular retinal and peripapillary nerve fiber layer (NFL) thickness and automated visual field (VF) findings. DESIGN: Cross-sectional observational study. METHODS: Retrospective institutional study where 150 consecutive eyes (101 subjects) from a glaucoma service were included. All the participants had full ophthalmic evaluation, VF testing and prototype OCT scanning at the same visit. Orthogonal OCT macular analysis was obtained to maximize the sampling of the area of interest. Pearson age-adjusted correlation was determined between macular retinal thickness and peripapillary NFL thickness. Area under the receiver operator characteristics (AROC) curves for the association between macular retinal thickness and peripapillary NFL thickness and VF findings were calculated in a subgroup of eyes without VF defect and eyes with VF defect confined to one hemifield. RESULTS: The correlation between macular retinal and peripapillary NFL measurements ranged between r =.27 to.54 for quadrants,.44 to.55 for hemiretina, and.52 for the overall mean. Areas under the receiver operator characteristics for macular thickness were higher in areas corresponding to the VF defect location than the noncorresponding locations. Areas under the receiver operator characteristics for peripapillary NFL thickness were higher than for the macular retinal thickness. Including both macular retinal thickness and peripapillary NFL thickness measurements in the logistic regression model yielded AROCs (range:.69 -.77) similar to those found for the peripapillary NFL alone. CONCLUSION: Macular retinal thickness, as measured by OCT, was capable of detecting glaucomatous damage and corresponded with peripapillary NFL thickness; however, peripapillary NFL thickness had higher sensitivity and specificity for the detection of VF abnormalities.     

New algorithm to analyze optical coherence tomographic images quantitatively

PURPOSE: To determine whether an algorithm we have developed can be used to measure the retinal thickness on optical coherence tomography (OCT) images. METHODS: Six radial linear scans of 6 mm were made with the OCT instrument. The retinal thickness and volume determined with the built-in algorithm for the OCT instrument for 50 eyes of 50 control subjects with normal retinal boundaries were compared to the values obtained with our algorithm. The macular volume was also measured in 26 eyes of 25 subjects before and after photodynamic therapy (PDT). RESULTS: The values obtained by the two algorithms in normal retinas were strongly correlated (R = 0.99). Bland-Altman plots of the mean differences between the two algorithm measurement values showed excellent agreement. The mean macular volume determined before and 1 week after PDT with the built-in algorithm was significantly larger than that measured with our algorithm (P = 0.035 pre-PDT; P = 0.004 1 week after PDT). CONCLUSIONS: Our algorithm can be used to obtain a valid measurement of retinal thickness in normal retinas. The macular volume before and 1 week after PDT obtained with the built-in algorithm was larger than those measurements obtained with our algorithm.     

Macular segmentation with optical coherence tomography

PURPOSE: To develop a software algorithm to perform automated segmentation of retinal layer structures on linear macular optical coherence tomography (StratusOCT; Carl Zeiss Meditec, Inc., Dublin, CA) scan images and to test its performance in discriminating normal from glaucomatous eyes in comparison with conventional circumpapillary nerve fiber layer (cpNFL) thickness measurement. METHODS: Four layer structures within the retina were defined: the macular nerve fiber layer (mNFL), the inner retinal complex (IRC; retinal ganglion cell [RGC] layer + inner plexiform and nuclear layers), outer plexiform layer (OPL), and outer retinal complex (ORC; outer nuclear layer + photoreceptor layer). Normal and glaucomatous eyes underwent fast macular map and fast NFL OCT scans. Linear macular images were analyzed using the developed algorithm, and the results were compared with the cpNFL thickness measurement. RESULTS: Forty-seven subjects (23 normal and 24 with glaucoma) were analyzed. mNFL, cpNFL, IRC, and the total retinal thicknesses were significantly greater in normal than in glaucomatous eyes (P < or = 0.0002; Wilcoxon), whereas OPL thickness did not show a significant difference (P = 0.46). ORC thickness was significantly greater in glaucomatous than normal eyes (P = 0.035). Areas under the receiver operator characteristic curve (AROCs) for discriminating normal from glaucomatous eyes were highest with mNFL + IRC (0.97) and lowest with OPL (0.56). AROCs for OPL and ORC were significantly smaller than those for mNFL, IRC, mNFL+IRC, and cpNFL (P < or = 0.01). AROCs for IRC, mNFL + IRC, and cpNFL were significantly larger than for retinal thickness (P < or = 0.049). Among the best-performing parameters (mNFL, IRC, mNFL + IRC, and cpNFL) there was no significant difference in AROCs (P > or = 0.15). CONCLUSIONS: The newly developed macular segmentation algorithm described herein demonstrated its ability to quantify objectively the glaucomatous damage to RGCs and NFL and to discriminate between glaucomatous and normal eyes. Further algorithm refinement and improvements in resolution and image quality may yield a more powerful methodology for clinical glaucoma evaluation.     

Regional variations in the relationship between macular thickness measurements and myopia

PURPOSE: To investigate the relationship between myopia and macular thickness, as measured by optical coherence tomography. METHODS: A total of 143 normal subjects comprising 80 eyes with high myopia (spherical equivalent [SE] < -6.0 D), 37 eyes with low to moderate myopia (SE between -6.0 and -0.5 D), and 26 nonmyopic eyes (SE > -0.5 D) were analyzed in this cross-sectional study. Total average, foveal, and inner and outer average macular thicknesses measured by the StratusOCT (Carl Zeiss Meditec Inc., Dublin, CA) were compared among the three diagnostic groups. Associations between macular thickness and refractive error/axial length were evaluated by linear regression analysis. RESULTS: The minimum foveal and average foveal (1-mm ring on the OCT retinal thickness map) thicknesses were significantly greater, and the outer ring macular (3-6-mm) thicknesses significantly lower in the high myopic eyes than in the low to moderate myopic and nonmyopic eyes. No significant difference was found in the inner ring (1-3-mm) macular thickness measurements among the groups. There was a positive correlation between the axial length and the average foveal thickness (r = 0.374, P < 0.001). Negative correlations were found between axial length and the average outer ring macular thickness (r= -0.471, P < 0.001) and total average macular thickness (r= -0.311, P < 0.001). CONCLUSIONS: Retinal thickness is related to refractive error/axial length in normal subjects with regional variations in correlation within the 6-mm macular region. Analysis of macular thickness in the evaluation of macular diseases and glaucoma should be interpreted only in the context of refractive errors and the location of measurement.     

Retinal nerve fiber layer assessment using optical coherence tomography with active optic nerve head tracking

PURPOSE: To develop an eye-motion-tracking optical coherence tomographic (OCT) method and assess its effect on image registration and nerve fiber layer (NFL) thickness measurement reproducibility. METHODS: A system capable of tracking common fundus features based on reflectance changes was integrated into a commercial OCT unit (OCT II; Carl Zeiss Meditec, Inc., Dublin, CA) and tested on healthy subjects and patients with glaucoma. Twenty successive peripapillary NFL scans were obtained with tracking and 20 without tracking, for 40 images in each session for each eye. Subjects participated in one session on three different days. Composite OCT scans and composite fundus images were generated for assessment of eye tracking. NFL thickness measurement reproducibility was also assessed. RESULTS: Seven healthy and nine glaucomatous eyes of 16 subjects were recruited. A qualitative assessment of composite OCT scans and composite fundus images showed little motion artifact or blurring along edges and blood vessels during tracking; however, those structures were less clearly defined when tracking was disengaged. There was no significant reproducibility difference with and without tracking in both intra- and intersession NFL measurement SD calculations in any location. The mean retinal pixel SD was significantly smaller with tracking than without (490.9 +/- 19.3 microm vs. 506.4 +/- 31.8 microm, P = 0.005, paired t-test). CONCLUSIONS: A retinal-tracking system was successfully developed and integrated into a commercial OCT unit. Tracking OCT improved the consistency of scan registration, but did not influence NFL thickness measurement reproducibility in this small sample study.     

Reproducibility of nerve fiber layer thickness measurements using optical coherence tomography in silicone oil-filled eyes

PURPOSE: To evaluate the reproducibility of nerve fiber layer (NFL) thickness measurements by optical coherence tomography (OCT) in individuals with silicone oil-filled eyes. METHODS: Eighteen patients who had undergone pars plana vitrectomy and silicone oil tamponade for retinal detachment were enrolled in a prospective, case-controlled clinical study. Each patient underwent OCT measurement of NFL thickness. Five repetitions of a series of scans on five separate occasions within a 0.5-month period were performed. Each eye was scanned at two different nerve head programs [radius (R) = 1.5 and R = 1.73]. The contralateral healthy eye was used as control. For each option (R = 1.5 and R = 1.73) and region (superior, inferior, temporal, nasal and overall mean), variance components and intraclass correlation coefficients (ICCs) were determined using repeated-measures regression. In these models, NFL thickness, as measured by OCT, was considered to have three variance components: intersubject, intervisit (within subject, between dates), and intravisit (within subject, within date). The ICC (intersubject variance/total variance) was used as a measure of reliability. RESULTS: The contralateral healthy eye provided a higher degree of reproducibility than the silicone oil-filled eye (p = 0.0001). Reproducibility was higher in a given eye on a given visit than from visit to visit. Reproducibility as measured by ICCs was as follows: R = 1.5, 0.54/0.30 (control eyes/silicone oil-filled eyes); R = 1.73, 0.51/0.30. CONCLUSIONS: Reproducibility results for OCT measurement of NFL thickness are different in healthy eyes and silicone oil-filled eyes. NFL thickness measurement is not reliable in silicone oil-filled eyes.     

Optical coherence tomography measurement of nerve fiber layer thickness and the likelihood of a visual field defect

PURPOSE: To determine if optical coherence tomography (OCT) measurements of nerve fiber layer (NFL) thickness can be used to predict the presence of visual field defects (VFD) associated with glaucoma.DESIGN: Quota-sampled, cross-sectional study.METHODS: Retrospective study of OCT NFL thickness measurements in 276 eyes of 276 subjects. All persons received OCT NFL thickness analysis; 136 eyes underwent frequency-doubling technology (FDT) perimetry; and 140 eyes underwent Swedish interactive threshold algorithm (SITA) perimetry. We defined a parameter called NFL(50), which is the NFL thickness value at which there was a 50% likelihood of a VFD with either SITA or FDT perimetry. We evaluated the use of NFL(50).RESULTS: The mean NFL thickness with (n = 68) and without (n = 68) a VFD in the FDT group was 93.2 microm +/- 22.6 and 108.4 microm +/- 14.1, respectively. The mean NFL thickness with (n = 70) and without (n = 70) a VFD in the SITA group was 78.9 microm +/- 24.8 and 103.0 microm +/- 18.0, respectively. The FDT mean NFL(50) value was 98.5 microm. The SITA mean NFL(50) value was 87.0 microm. The area under the receiver operator characteristic (AROC) curve for mean NFL was 0.73, and the positive predictive value (PPV) for FDT mean NFL(50) was 72.2%. For SITA mean NFL, the AROC was 0.79 and the PPV for NFL(50) was 77.2%.CONCLUSION: Nerve fiber layer thickness analysis using OCT may be clinically useful in identifying subjects who have visual field loss. However, the PPV suggests that OCT may need higher resolution and better reproducibility to enhance its sensitivity and specificity for population screening.     

Retinal thickness in healthy and diabetic subjects measured using optical coherence tomography mapping software

PURPOSE: To define the normal retinal thickness in healthy subjects using optical coherence tomography (OCT) mapping software and to assess the ability of OCT to detect early macular thickening in diabetic patients. METHODS: Six radial scans centered on the fixation point were done on 60 healthy eyes and 70 eyes of 35 diabetic patients without macular edema on biomicroscopy. Retinal thickness was measured automatically with OCT mapping software. Mean retinal thickness was compared in subgroups of healthy patients based on age, sex, and eye, and in the eyes of diabetic patients and healthy subjects. Thickening was diagnosed if mean retinal thickness of an area was greater than the mean thickness + 2SD in the corresponding area in healthy subjects; or if the difference between right and left eye exceeded the mean difference + 2 SD in a given area in healthy subjects. RESULTS: In healthy subjects, mean retinal thickness in the central macular area 1000 microm in diameter was 170+/-18 microm. There was no significant difference according to age, or left or right eye, but central macular thickness was significantly greater in men than women (p=0.0139). No difference was observed between the eyes of healthy subjects and diabetic patients without macular edema on biomicroscopy, but OCT detected early macular thickening in 12 diabetic eyes. CONCLUSIONS: In this study average retinal thickness and mean local variations in a normal population were defined using a commercially available mapping software. OCT seems a sensitive tool for detecting early retinal thickening.     

Evaluating pulsatile ocular blood flow analysis in normal and treated glaucomatous eyes

PURPOSE: To evaluate pulsatile ocular blood flow (POBF) analysis in normal subjects and glaucoma patients by comparison of POBF measurements with functional (as determined by visual field [VF]) and structural (as determined by optical coherence tomography [OCT]) measures. DESIGN: Prospective, cross-sectional study. METHODS: Forty-one eyes of 24 consecutive glaucoma patients and 20 eyes of 10 healthy subjects were studied; POBF analysis was performed on all subjects at the same visit as VF testing and OCT retinal nerve fiber layer (NFL) thickness measurement. The mean results of normal and glaucomatous eyes were compared for each method. Correlation between measurements obtained with each modality and the discriminating power using receiver operator characteristic curves was tested. RESULTS: The mean POBF (standard deviation [SD]) in the normal group was 1,010.4 (292.8) microl/min and 989.3 (305.5) microl/min in the glaucoma group (P =.90). Significant differences between groups were found for VF mean deviation and pattern standard deviation (P =.02, P =.004, respectively) and OCT mean NFL thickness (P <.0001). No correlation was found between POBF parameters and intraocular pressure, VF, or OCT variables except for intraocular pressure in glaucoma group (r = -.43, P =.003). The area under the receiver operator characteristic curves was higher for VF indexes and OCT mean NFL thickness than POBF parameters for distinguishing between normal and glaucomatous eyes. CONCLUSIONS: The wide range of normal values and the low discriminating power of POBF between normal and glaucomatous eyes limits the clinical use of the device for glaucoma patients.     

光学相干断层成像与组织形态学检测猴青光眼视网膜神经纤维层厚度的比较

目的应用光学相干断层成像术（optical coherence tomography,OCT）检测活体青光眼视网膜神经纤维层（retinal nerve fiber layer,RNFL）厚度,并与组织形态学检测结果进行比较。方法选用Cynomolgus猴4只眼,通过氩激光烧灼小梁网,引起眼压升高,制作成青光眼动物模型。应用OCT测量视盘周围直径,选取直径为2.4mmRNFL厚度的猴眼进行研究。在完成最后一次OCT测量后,将眼球摘除。摘除的眼球置于10％甲醛液中固定,石蜡包埋做连续切片及HE染色。应用与光学显微镜相联接的计算机图像处理系统,测量与OCT扫描相对应点的组织学切片的RNFL厚度。结果OCT测量RNFL平均厚度为（72.2±54.5）μm;组织形态学测量RNFL平均厚度为（70.3±51.1）μm,未经校正的组织形态学测量平均厚度为（61.1±44.2）μm。两种检测结果差异无显著性（t=1.895,P＞0.05）。结论OCT活体测量RNFL的平均厚度与组织形态学测量结果基本相同,但OCT活体测量RNFL厚度值与经校正后的组织形态学测量结果更接近。     

Symmetry of optical coherence tomography retinal measurements in young children

PURPOSE: To examine symmetry of macular, peripapillary nerve fiber layer (NFL), and optic disk measurements in healthy children. DESIGN: Cross-sectional study. METHODS: We examined a population-based sample of six-year-old children (n = 1,765) in the Sydney Childhood Eye Study. Optical coherence tomography (OCT) scan data for right and left eyes were compared. RESULTS: High interocular correlations (>0.8) were found for foveal minimum thickness and cup-to-disk ratios. Average NFL thickness was moderately correlated (0.7). Other macular, NFL, and optic disk parameters showed negligible or small mean interocular differences. In 95% of children, interocular difference in macular thickness was <22 microm for foveal minimum and <40 microm for other areas, and 16 to 17 microm for average NFL thickness. Cup-to-disk ratio was highly symmetric, varying by <0.25 in 95% of children. CONCLUSIONS: Interocular asymmetry of retinal/optic disk parameters should be interpreted in the context of other clinical measures because of the potential for large degrees of asymmetry among individuals.     

Effect of posterior capsular opacification removal on macular optical coherence tomography

PURPOSE. To evaluate the influence of posterior capsular opacification (PCO) on macular optical coherence tomography (OCT) imaging quality and measurements of macular retinal thickness. METHODS. In this prospective interventional case series, 32 eyes of 23 patients with PCO were recruited. Best-corrected visual acuity (BCVA), a complete ophthalmologic assessment, and macular OCT scans (OCT Stratus 3000) before and after Nd:YAG capsulotomy were performed. Two parameters for image quality (signal strength (SS) and number of tomographic messages) and 10 macular retinal thickness measurements were compared. Spearman correlations between BCVA and SS and macular retinal thickness measurements before and after capsulotomy were also performed. RESULTS. PCO removal was associated with an increase of best-corrected visual acuity (p<0.0001). The mean SS (n=32) went from 3.34+/-2.31 to 6.38+/-1.93 (p<0.0001) after Nd:YAG capsulotomy. The SS improved in 26 of 32 eyes. No significant difference between mean preoperative and postoperative macular retinal thickness measurements was observed (p<0.05) in valuable scans. Before capsulotomy, a correlation existed between BCVA and SS. After capsulotomy this correlation was no longer found. CONCLUSIONS. OCT image quality is influenced by PCO. Nd:YAG capsulotomy results in a measurable improvement in SS and improvement in the number of valuable examinations. Valuable OCT scans in patients with PCO seem to yield reliable measurements of macular retinal thickness even in the presence of severe PCO. The correlation between BCVA and SS before capsulotomy suggests that the SS could be considered an objective indicator of the degree of PCO.     

A pilot study of Fourier-domain optical coherence tomography of retinal dystrophy patients

PURPOSE: To characterize the macular anatomy of retinal dystrophy eyes using high-speed, high-resolution, Fourier-domain optical coherence tomography (FD-OCT). DESIGN: Case-control study. METHODS: Retinal dystrophy patients and normal age- and gender-matched controls underwent FD-OCT imaging using the RTVue (Optovue Inc., Fremont, California, USA). Vertical and horizontal 8-mm scans of 1024 lines/cross-section were obtained. Based on boundaries manually drawn on computer displays of OCT cross-sections, the thicknesses of the retina, inner retinal layer (IRL), and outer retinal layer (ORL) were averaged over both 5-mm (macular) and 1.5-mm (foveal) regions centered at the fovea. The IRL was the sum of nerve fiber layer (NFL), ganglion cell layer (GCL), and inner plexiform layer (IPL) thicknesses. Total retinal thickness (RT) was measured between the internal limiting membrane (ILM) and the retinal pigment epithelium. ORL thickness was calculated by subtracting IRL thickness from RT. RESULTS: Fourteen patients (three retinitis pigmentosa, two cone-rod degeneration, two Stargardt disease, and seven normal controls) underwent FD-OCT imaging. Mean foveal RT was 271.3 +/- 23.3 microm for controls and 158.4 +/- 47.1 microm for retinal dystrophy patients (P < .001). Mean macular RT was 292.8 +/- 8.1 microm for controls and 199.1 +/- 32.6 microm for retinal dystrophy patients (P < .001). Mean macular ORL was 182.9 +/- 4.7 microm for controls and 101.3 +/- 18.7 microm for retinal dystrophy patients (P < .001); mean macular IRL was 109.9 +/- 6.4 microm for controls and 97.9 +/- 20.7 microm for retinal dystrophy patients (P = .06). CONCLUSION: Eyes with retinal dystrophy had a small (11%) decrease in macular IRL and severe (45%) decrease in macular ORL compared to normal controls.     

Reproducibility of and effect of magnification on optical coherence tomography measurements in children

PURPOSE: To determine the reproducibility of optical coherence tomography (OCT) measurements of macular thickness, peripapillary nerve fiber layer (NFL) thickness, and optic disk parameters and to investigate the effect of axial length and refractive error on these measurements in children with healthy eyes. DESIGN: Cross-sectional study. METHODS: The Sydney Childhood Eye Study examined 2,353 year 7 students (75.3% response) from a random cluster sample of 21 secondary schools across Sydney. A consecutive subsample of 120 children had OCT (StratusOCT, Carl Zeiss, Dublin, California, USA) performed by a single operator, which was repeated with a brief rest between the two sessions. Scans of the NFL, macula, and optic disk were performed. RESULTS: Intersubject variability of measurements of macular thickness, NFL thickness, and optic disk parameters assessed using intraclass correlation coefficients accounted for >85%, >62%, and >38% of total variability of measurements, respectively. Corresponding coefficients of variability were <5%, <8%, and <13%. Magnification effects attributable to axial length and refractive error on the measurement of these parameters were statistically not significant. CONCLUSION: The StratusOCT demonstrated reproducible measurements of macular and NFL thickness. Measurement of most optic disk parameters were also reproducible. Magnification attributable to axial length and refractive error had minimal impact on measurements of macular and NFL thickness.     

Reproducibility of nerve fiber thickness, macular thickness, and optic nerve head measurements using StratusOCT

PURPOSE: The measurement reproducibility of the third generation of commercial optical coherence tomography, OCT-3 (StratusOCT, software ver. A2, Carl Zeiss Meditec Inc., Dublin, CA) was investigated. The nerve fiber layer (NFL) thickness, macula thickness map, and optic nerve head (ONH) parameters in normal eyes were studied. METHODS: Ten normal subjects were imaged six times (three before and three after dilation) per day, and the series was repeated on three different days. The order of the scans before pupil dilation was randomized in each of the 3 days of scanning. After pupil dilation, the scans were also randomized in each of the 3 days of scanning. Each series was performed separately for standard-density (128 A-scans per macular and ONH image and 256 A-scans per NFL image) and high-density (512 A-scans per image for all three scan types) scanning. RESULTS: The mean macular thickness was 235 +/- 9.8 micro m. A-scan density (or image acquisition speed) had a statistically significant effect (P < 0.05) on the reproducibility of the mean macular thickness, macular volume, and a few sectors of the macular map. No significant dilation effect was found for any of the macular parameters. The best intraclass correlation coefficient (ICC; 94%) for macular scans was found for dilated high-density scanning, with an intervisit SD of 2.4 micro m and an intravisit SD of 2.2 micro m. The mean NFL thickness for standard scanning was 98 +/- 9 micro m. NFL reproducibility showed mixed results and had interactions between scan density and dilation for some parameters. For most of the NFL parameters, reproducibility was better with dilated standard-density scanning. The mean NFL thickness ICC for dilated standard scanning was 79%, with an intervisit SD of 2.5 micro m and an intravisit SD of 1.6 micro m. For the ONH analysis, the reproducibility was better for dilated standard-density scanning for almost all the parameters, except for disc area, horizontal integrated rim volume, and vertical integrated rim area, which were better before dilation. The best reproducibility was found for cup-to-disc ratio (ICC = 97%, with intervisit SD of 0.04 micro m and intravisit SD of 0.02 micro m). CONCLUSIONS: StratusOCT demonstrated reproducible measurements of NFL thickness, macular thickness, and optic nerve head parameters. The best reproducibility was found for dilated standard scanning for NFL and ONH parameters and for dilated high-density scanning for macular parameters.     

Intersession repeatability of macular thickness measurements with the Humphrey 2000 OCT

PURPOSE: This study was designed to determine intersession repeatability of measurements of macular thickness made with a commercially available optical coherence tomography (OCT) system. The images that can be routinely acquired with the commercial instrument differ significantly in quality from the images in the literature, which have mostly been acquired on prototype systems. METHODS: Multiple OCT images of the nasal macula were obtained from the right eye during three independent measuring sessions, using the Humphrey 2000 OCT system (Humphrey, San Leandro, CA). Twenty-six volunteers with no history of ocular disease participated in this investigation. Eyes in all subjects were undilated during scan acquisition. Scans were horizontal, 3 mm long, and through the fovea. Five scans were used from each session, for a total of 15 scans per subject. Retinal boundaries were automatically detected using custom software. Statistical software was used to calculate intersession and intrasession repeatability. Manual correction was performed on the automatically detected boundaries, and a second analysis was performed using these boundaries. RESULTS: When no manual correction of boundaries was performed, there were no significant effects between different sessions (P = 0.529) or between different scans within the same session (P = 0.509). Average retinal thickness was found to be 274 +/- 17 microm for a 1-mm long region 0.75 mm from the fovea. Individual scan averages differed from overall patient averages by 0 +/- 4.3 microm (99% confidence interval, 11.2 microm). CONCLUSIONS: OCT measurements of macular thickness made with the Humphrey 2000 OCT system are repeatable over different sessions with an expected variation of less than 11 microm (99% confidence interval).