Reproducibility Of Retinal Thickness Measurements Research Articles

Reproducibility of Portable OCT and Comparison with Conventional OCT.

Optical coherence tomography (OCT) is an indispensable instrument in ophthalmology; however, some facilities lack permanent OCT devices. ACT100, a portable SD-OCT system, allows for medical examinations at hospitals that do not have OCT and house calls. We investigated the usefulness of ACT100 by examining the reproducibility of retinal thickness measurements in 35 healthy participants with normal eyes using ACT100 and Cirrus. Using two OCTs, the OCT imaging of both eyes of each subject was performed. Macular retinal thickness was evaluated using the average value in nine lesions of the Early Treatment Diabetic Retinopathy Study (ETDRS) circle. Both models captured images in all cases. In the right eye, mean retinal thickness was significantly lower than in the ACT100 group in all regions; however, the measured values correlated well. The intraclass correlation coefficients showed the same high reliability as the Cirrus. The coefficients of variation (CVs) of both models showed little variation and high stability; however, the CV of ACT100 was significantly higher. The left eye was almost identical. Macular retinal thickness measured using ACT100 showed slightly greater variability than that by Cirrus; the reproducibility was good and correlated well with that of Cirrus. This technique is a suitable alternative to conventional OCT.

REPRODUCIBILITY AND REPEATABILITY OF CIRRUS AND SPECTRALIS FOURIER-DOMAIN OPTICAL COHERENCE TOMOGRAPHY OF HEALTHY AND EPIRETINAL MEMBRANE EYES

To evaluate the accuracy and reproducibility of retinal thickness measurements in healthy and epiretinal membranes (ERM) eyes by Cirrus and Spectralis Fourier-domain optical coherence tomography devices. Eighty-seven ERM and 122 healthy subjects underwent 3 macular scans using both optical coherence tomography instruments. Mean thickness measurements in the nine Early Treatment Diabetic Retinopathy Study areas were compared, evaluating the repeatability and the relationship between devices. Macular thickness increase was detected in ERM eyes for all optical coherence tomography parameters (P < 0.001). Mean foveal thickness was 423.5 ± 81.4 and 438.0 ± 54.2 μm for ERM eyes and 267.1 ± 20.2 and 277.5 ± 18.9 μm for healthy eyes using Cirrus and Spectralis, respectively. Macular average thickness in ERM eyes as determined by both optical coherence tomography was correlated (r = 0.812; P < 0.001) but significantly different (P = 0.044). In ERM eyes, measurements showed a mean of the coefficients of variation of 2.95%, 2.2%, and 1.01% using Cirrus, Spectralis, and Spectralis progression feature, respectively. Intraclass correlation coefficients were higher than 0.919 in all cases. Reproducibility of both Cirrus and Spectralis optical coherence tomography was high in healthy and ERM eyes. However, considerable differences were found between macular thickness measurements obtained by both devices despite the high correlation between them.

Repeatability and Reproducibility of Retinal Thickness Measurements in Diabetic Patients with Spectral Domain Optical Coherence Tomography

ABSTRACTBackground: To determine the repeatability and reproducibility of optical coherence tomography (OCT) Spectralis retinal thickness measurements in diabetic patients with clinically significant macular edema (CSME).Methods: Twelve eyes of 12 volunteers (without macular pathology – control group) and 21 eyes of 21 diabetic patients with CSME were included in the study. Reproducibility, repeatability, intraclass correlation coefficients (ICCs) and intrasession correlation coefficients were tested with 20 × 15 degree raster scans consisting of 19 high-resolution line scans that were repeated three times by two experienced examiners.Results: In the control group, examining all regions, coefficient of repeatability was less than 1.1%, while coefficient of reproducibility was less than 2.2%. In diabetic patients, examining all regions, coefficient of repeatability was less than 2.6%, while coefficient of reproducibility was less than 2.4%. ICCs were, respectively, greater than or equal to 0.98 in the control group and 0.99 in diabetic patients. Intrasession coefficients of variation were less than 0.4% in the control group and less than 0.5% in diabetic patients.Conclusion: Retinal thickness measurements are repeatable and reproducible with OCT Spectralis in both the control group and diabetic patients. The results indicate that a change in central subfield thickness exceeding 12 µm and 3% in the diabetic patients is likely to be real.

Changes in macular thickness measurements repeatability with age using Cirrus Fourier‐domain optical coherence

AbstractPurpose To test the intrassession reproducibility of retinal thickness measurements using Cirrus Fourier‐domain optical coherence tomography (OCT). To evaluate if there is any relation between macular measurements repeatability and age of the studied subject.Methods Two hundred and nine of 209 healthy subjects underwent three macular 512x128 volume cube centered on the fovea done by the same experienced examiner using Cirrus HD OCT (Carl Zeiss, USA). Descriptive statistics, analysis of variance, intraclass correlation coefficients (ICC), and coefficients of variation (COV) were calculated for the 9 macular areas described by the Early Treatment Diabetic Retinopathy Study (ETDRS) in the macular protocol. Values were analysed related to other subject factors like age and VA.Results All measurements were highly reproducible. The ICCs ranged from 0.823 to 0.992 using macular volume cube. Mean COV was 1.4 ±1.09% (ranged from 0.7 to 1.9%) for the nine ETDRS areas. COV values increased with age; a significant correlation was found between them (r=0.300, p≤0.001). COVs were also related to VA.Conclusion Retinal thickness measurements obtained using Cirrus Fourier‐domain OCT show good reproducibility for healthy eyes. Repeatability is related to the subject age.

REPEATABILITY AND REPRODUCIBILITY OF RETINAL THICKNESS MEASUREMENTS WITH SPECTRAL-DOMAIN OPTICAL COHERENCE TOMOGRAPHY USING DIFFERENT SCAN PARAMETERS

To evaluate repeatability (test-retest) and reproducibility of retinal thickness measurements using spectral-domain optical coherence tomography with different densities of A-scans per B-scan and different frames per B-scan for real-time averaging. Twelve healthy subjects were analyzed by spectral-domain optical coherence tomography. Raster lines analysis with 19 B-scans over the examined area centered on the macula was performed. Images were acquired both in standard-density (768 A-scans/B-scan) and high-density (1,536 A-scans/B-scan) modalities. Moreover, images were acquired using 2 and 20 frames/B-scan for real-time averaging. Each analysis was repeated twice to test for repeatability. Intersession repeatability was good for all studied analysis protocols, with Lin concordance correlation coefficient values ranging between 0.88 and 1.00. Reproducibility assessment showed consistent retinal thickness measurements using variable scan density, with Bland-Altman limits of agreement of -6 μm to 6 μm in the central area. Reproducibility assessment showed consistent retinal thickness measurements using different number of frames used in the real-time averaging process, with Bland-Altman limits of agreement of -8 μm to 4 μm in the central area. Spectral-domain optical coherence tomography is a very reliable tool for central retinal thickness assessment. Changes in the number of A-scans/B-scan and in frames used for real-time averaging do not affect repeatability and reproducibility.

Reproducibility of retinal thickness measurements in eyes with uveitic macular oedema using Spectralis optical coherence tomography

Editor, In eyes with uveitic macular oedema, the reproducibility of retinal thickness measurements is an essential parameter to monitor the progression of the disease and/or the therapeutic results. To date, there are no reports concerning reproducibility of optical coherence tomography (OCT) in this type of oedema. The aim of the present study is to value the intraobserver reproducibility of macular thickness measurements performed with Spectralis OCT (Heidelberg Engineering, Heidelberg, Germany) in inflammatory macular oedema. Thirty-three eyes of 33 consecutive patients, 15 men and 18 women, mean age 35.09 ± 16.64 years (range: 7–77) with uveitis and concurrent macular oedema were included in the study. All patients underwent three consecutive OCT examinations with Spectralis OCT performed by the same operator within one session. For retinal thickness measurements, 20 × 15 degree raster scans were taken consisting of 37 high-resolution line scans. The foveolar centre-point retinal thickness (CPT) and the Early Treatment of Diabetic Retinopathy Study (ETDRS) 9 region map were used for quantitative evaluation. The coefficient of repeatability (CR) was calculated according to Bland & Altman (1996). Also, coefficient of variation (COV) was obtained (Menke et al. 2009a,b). For the statistical analysis, Student’s t-test and Kendall’s τ correlation coefficient were used. p-value <0.05 was considered statistically significant. The results are summarized in Table 1. No significant correlation between thickness and CR and between thickness and COV was found (Kendall’s τ correlation coefficients = 0.022, −0.244; p = 0.29, 0.32). Our highest CR and COV were in the foveolar CPT. One reason we can suggest for this result is that the retinal thickening and the presence of most cysts in central area may affect the device measurement process and can slightly degrade the precision of the reproducibility. Also, we think that highest CR and COV in central area may be caused by a reduced fixation ability of patient owing to macular oedema. Nevertheless for the clinical practice, our findings show in any case an excellent index of reproducibility. This evidence is supported by the data reporting no significant difference between the measurements of CPT. The reproducibility can vary according to different OCT models. In eyes with diabetic macular oedema, Polito et al. (2005) reported a COV ranged from 4.84% to 8.33% using stratus OCT 3 (Carl Zeiss Meditec Inc., Dublin, CA, USA). Recently, some studies have reported high reproducibility of the new OCT generation in healthy eyes and in eyes with age-related macular degeneration (Menke et al. 2009a,b). There are not too many studies that compared reproducibility between different OCT types to make a firm statement about the “most reproducible” instrument. Wolf-Schnurrbusch et al. (2009) compared the intersession reproducibility of different commercially available OCT instruments concluding that Spectralis OCT showed the lowest COV (0.46%). The excellent reproducibility with Spectralis OCT is attributable to some technical features such as image speed, greater resolution and retinal segmentation algorithms, which increase the examination performance. However, the most important factor determining the high reproducibility is the eye-tracking mechanism that permits to scan the same scanning location on following visits. In inflammatory macular oedema, an excellent reproducibility permits to consider even any minimal thickness change as a real effect of the therapy and not as a consequence of a measurement error. As far as we know, this is the first study on the reproducibility of retinal thickness measurements in uveitic macular oedema using Spectralis OCT. As we did not study the reproducibility of the OCT performed by different operators, further studies will be needed to test the interobserver reproducibility in such a disease.

Reproducibility of retinal thikness measurements in patients with age‐related macular degeneration using fourier –domain optical coherence tomography

AbstractPurpose To assess the reproducibility intraoperative macular thickness measurements using optical coherence tomography, spectral domain (spectralis, Heidelberg Engineering, Germany) in patients with wet AMD and to evaluate differences in reproducibility with optical coherence tomography (Stratus, Carl Zeiss Meditect Inc, USA).Methods prospective observational study and cross‐sectional study included 30 eyes of 30 patients with exudative AMD. All of them were dealt with macular status by fast‐track protocol posterior pole with spectral domain OCT (Spectralis OCT) and time domain OCT (Stratus OCT). Each patient underwent 3 consecutive scans each of the scanners and performed by the same observer to compare the reproducibility of both devices. We evaluated the central macular thickness in macular different areas described in the ETDRS (Early Treatment Diabetic Retinopathy Study).Statistics was performed descriptive analysis of variance and calculated the intraclass coefficient of correlation (ICC) and coefficients of variationResults The thickness of the retina was highly reproducible for all ETDRS areas with OCT Spectralis with values of ICC and VOC better than the Stratus OCT. VOCs spectralis were obtained with less than 5% indicating a high reproducibility and the ICC greater than 0.9.Conclusion Reproducibility of retinal thickness measurements with optical coherence tomography spectral domain is almost perfect, there are few differences in intraobserver assessments. The values ​​are higher than getting with time‐domain OCT .Fourier domain OCT is a valid and highly reliable device for diagnosis and monitoring of retinal diseases such as wet AMD.

Quality and Reproducibility of Retinal Thickness Measurements in Two Spectral-Domain Optical Coherence Tomography Machines

To evaluate the accuracy and reproducibility of retinal thickness measurements in exudative age-related macular degeneration (AMD) by the Spectralis (Heidelberg Engineering, Heidelberg, Germany) and the Cirrus (Carl Zeiss Meditec, Dublin, CA) optical coherence tomography (OCT) systems. Eyes with exudative age-related macular degeneration were randomly assigned to one of eight groups, each different in the sequence of examiner and OCT system. The 512 × 128 cube program of the Cirrus and the 30° × 25° volume scan containing 32 lines of the Spectralis were performed twice. The correlation between the examinations was expressed by the interclass correlation coefficient (ICC). Enrolled in the study were 112 patients and 112 eyes (mean age, 76.5 ± 7.9 years; range 51-89), with 14 patients in each group. The mean error scores per line were 0.53 and 0.52 in the Cirrus, significantly (P < 0.001) lower than in the Spectralis (0.83 and 0.98). For automatic central retinal thickness (CRT), the ICC for Cirrus (all examinations calculated) was 0.61 for groups 1 to 4 (the same examiner) and 0.65 for groups 5 to 8 (two different examiners); for Spectralis (13.4% not calculated) the ICC was 0.93 for groups 1 to 4 and 0.86 for groups 5 to 8. After error correction, the Cirrus ICC improved to 1.0 and 0.99 and the Spectralis ICC to 1.0 in both groups. Considerable differences were found between the two systems, both of which incorporate the spectral-domain technology. Different positioning of segmentation lines, control of localization, density of included scan lines, and number of available maps explain the differences in segmentation quality and reproducibility. Manual correction of segmentation and centralization improves the reproducibility.

Reproducibility of retinal thickness measurements in patients with age‐related macular degeneration using 3D Fourier‐domain optical coherence tomography (OCT) (Topcon 3D‐OCT 1000)

Conventional time-domain optical coherence tomography (OCT) has become an important tool for following dry or exudative age-related macular degeneration (AMD). Fourier-domain three-dimensional (3D) OCT was recently introduced. This study tested the reproducibility of 3D-OCT retinal thickness measurements in patients with dry and exudative AMD. Ten eyes with dry AMD and 12 eyes with exudative AMD were included in the study. Sets of three OCT 6 × 6-mm raster scans were taken by one operator. Mean retinal thickness was calculated for 36 areas. Coefficients of variation (CoV) were calculated for each patient and area. For analysis, two separate areas (central and peripheral) were defined. Generalized estimating equations (GEEs) were applied to all 36 subfields in order to analyse possible differences in CoV and mean retinal thickness between dry and exudative AMD. Mean retinal thickness values were significantly larger in the central area in exudative AMD (p < 0.001). Mean CoV for exudative AMD was 3.7% (standard deviation [SD] 1.4%). Mean CoV for dry AMD was 1.8 (SD 0.6%). The reproducibility of retinal thickness measurements was significantly less in exudative AMD (p = 0.009). Reproducibility of 3D-OCT retinal thickness measurements was good in both groups. However, reproducibility was significantly better in dry AMD than in exudative AMD.

Reproducibility of Retinal Thickness Measurements on Normal and Pathologic Eyes by Different Optical Coherence Tomography Instruments

To compare retinal thickness measurements produced by different time-domain and spectral-domain optical coherence tomography (TD-OCT and SD-OCT) devices when imaging normal and pathologic eyes. Prospective, observational study in an academic institutional setting. A total of 110 eyes were imaged by 6 different OCT devices: Stratus and Cirrus (Carl Zeiss Meditec Inc), Spectralis HRA+OCT (Heidelberg Engineering), RTVue-100 (Optovue Inc), SDOCT Copernicus HR (Optopol Technology S.A.), and 3D OCT-1000 (Topcon Corporation). Eyes were normal or affected by different pathologies of the retina, including exudative and nonexudative age-related macular degeneration, epiretinal membrane, cystoid macular edema, and macular hole. For each instrument we used standard analysis protocols for macular thickness evaluation. Mean retinal thickness values between the instruments in the ETDRS central circular 1000-μm-diameter areas and in the ETDRS midperipheral circular 3000-μm-diameter areas were compared. The 6 different devices produced measurements that differ in variance (Bartlett test, P = .006), and mean values (Friedman test, P < .001). Bland-Altman analysis revealed that the limits of agreement for all the comparisons were not acceptable. Regression was calculated and it was elaborated into a conversion table, despite a high standard error for both intercepts and slope conversion values. This study suggests that retinal thickness measurements obtained with various OCT devices are different beyond clinical practice tolerance, according to Bland-Altman analysis. Furthermore, regression analysis reveals high standard error values. These differences appear to be primarily attributable to the analysis algorithms used to set retinal inner and outer boundaries.

Repeatability and Reproducibility of Retinal Thickness Measurements by Optical Coherence Tomography in Age-Related Macular Degeneration

To evaluate the repeatability and reproducibility of retinal thickness measurements in exudative age-related macular degeneration (AMD) using Stratus optical coherence tomography (OCT) (Carl Zeiss Meditec, Inc., Dublin, CA). Prospective, observational case series. A total of 200 eyes of 200 subjects with exudative AMD. Macular thickness and fast macular thickness programs of Stratus OCT were performed twice by the same examiners or 2 different examiners. The sequence of examiners was randomized 1:1:1:1. The variability of 1-mm subfield central retinal thickness (CRT), center point thickness (CPT), and retinal volume (RV) was calculated. Interobserver and intraobserver variability of retinal thickness measurements. Ninety-nine patients/eyes were enrolled in study arm 1 (repeated by the same examiner), and 101 patients/eyes were enrolled in study arm 2 (repeated by different examiners). Values of CPT, CRT, and RV were well correlated (interclass correlation coefficient, 0.71-0.93) in both study arms, revealing better results for the macular thickness program than for the fast macular thickness program. Threshold algorithm line failures were significantly correlated to the absolute differences of 2 repeated measurements for CPT, CRT, and RV but not with manually corrected maximum retinal thickness (MRT). Maximum retinal thickness was significantly influenced by the examiner performing the measurement. Age, lesion composition, examiner performing OCT examination, and sequence of examination had no significant influence. The repeatability and reproducibility of retinal thickness measurements were high, presenting better results for CRT and RV versus CPT, and for the macular thickness program versus the fast macular thickness program. The reliability of retinal thickness measurement was most frequently affected by algorithm line failures and fixation problems. A possible solution may be manually corrected measurement, such as MRT.

COMPARISON OF SPECTRAL/FOURIER DOMAIN OPTICAL COHERENCE TOMOGRAPHY INSTRUMENTS FOR ASSESSMENT OF NORMAL MACULAR THICKNESS

The purpose of this study was to report normal macular thickness measurements and assess reproducibility of retinal thickness measurements acquired by a time-domain optical coherence tomography (OCT) (Stratus, Carl Zeiss Meditec, Inc., Dublin, CA) and three commercially available spectral/Fourier domain OCT instruments (Cirrus HD-OCT, Carl Zeiss Meditec, Inc.; RTVue-100, Optovue, Inc., Fremont, CA; 3D OCT-1000, Topcon, Inc., Paramus, NJ). Forty randomly selected eyes of 40 normal, healthy volunteers were imaged. Subjects were scanned twice during 1 visit and a subset of 25 was scanned again within 8 weeks. Retinal thickness measurements were automatically generated by OCT software and recorded after manual correction. Regression and Bland-Altman plots were used to compare agreement between instruments. Reproducibility was analyzed by using intraclass correlation coefficients, and incidence of artifacts was determined. Macular thickness measurements were found to have high reproducibility across all instruments with intraclass correlation coefficients values ranging 84.8% to 94.9% for Stratus OCT, 92.6% to 97.3% for Cirrus Cube, 76.4% to 93.7% for RTVue MM5, 61.1% to 96.8% for MM6, 93.1% to 97.9% for 3D OCT-1000 radial, and 31.5% to 97.5% for 3D macular scans. Incidence of artifacts was higher in spectral/Fourier domain instruments, ranging from 28.75% to 53.16%, compared with 17.46% in Stratus OCT. No significant age or sex trends were found in the measurements. Commercial spectral/Fourier domain OCT instruments provide higher speed and axial resolution than the Stratus OCT, although they vary greatly in scanning protocols and are currently limited in their analysis functions. Further development of segmentation algorithms and quantitative features are needed to assist clinicians in objective use of these newer instruments to manage diseases.

Reliability and reproducibility of macular segmentation using a custom-built optical coherence tomography retinal image analysis software

We determine the reliability and reproducibility of retinal thickness measurements with a custom-built OCT retinal image analysis software (OCTRIMA). Ten eyes of five healthy subjects undergo repeated standard macular thickness map scan sessions by two experienced examiners using a Stratus OCT device. Automatic/semi automatic thickness quantification of the macula and intraretinal layers is performed using OCTRIMA software. Intraobserver, interobserver, and intervisit repeatability and reproducibility coefficients, and intraclass correlation coefficients (ICCs) per scan are calculated. Intraobserver, interobserver, and intervisit variability combined account for less than 5% of total variability for the total retinal thickness measurements and less than 7% for the intraretinal layers except the outer segment/ retinal pigment epithelium (RPE) junction. There is no significant difference between scans acquired by different observers or during different visits. The ICCs obtained for the intraobserver and intervisit variability tests are greater than 0.75 for the total retina and all intraretinal layers, except the inner nuclear layer intraobserver and interobserver test and the outer plexiform layer, intraobserver, interobserver, and intervisit test. Our results indicate that thickness measurements for the total retina and all intraretinal layers (except the outer segment/RPE junction) performed using OCTRIMA are highly repeatable and reproducible.

Reproducibility of Retinal Thickness Measurements in Healthy Subjects Using Spectralis Optical Coherence Tomography

To test the reproducibility of retinal thickness measurements in healthy volunteers of a new Frequency-domain optical coherence tomography (OCT) device (Spectralis OCT; Heidelberg Engineering, Heidelberg, Germany). Prospective, observational study. Forty-one eyes of 41 healthy subjects were included into the study. Intraobserver reproducibility was tested with 20 x 15 degree raster scans consisting of 37 high-resolution line scans that were repeated three times by one examiner (M.N.M.). Mean retinal thickness was calculated for nine areas corresponding to the Early Treatment Diabetic Retinopathy Study (ETDRS) areas. Coefficients of variation (COV) were calculated. Retinal thickness measurements were highly reproducible for all ETDRS areas. Mean total retinal thickness was 342 +/- 15 microm. Mean foveal thickness was 286 +/- 17 microm. COVs ranged from 0.38% to 0.86%. Lowest COV was found for the temporal outer ETDRS area (area 7; COV, 0.38%). Highest COV was found for the temporal inner ETDRS area (area 3; COV, 0.86%). Mean difference between measurement 1 and 2, measurement 1 and 3, and measurement 2 and 3 for all ETDRS areas was 1.01 microm, 0.98 microm, and 0.99 microm, respectively. Spectralis OCT retinal thickness measurements in healthy volunteers showed excellent intraobserver reproducibility with virtually identical results between retinal thickness measurements performed by one operator.

Reproducibility of OCT in choroidal neovascularization secondary to ARMD

Abstract Purpose: Optical coherence tomography (OCT) is commonly used to quantitatively measure macular thickness in several macular diseases, especially in conditions associated with macular vascular leakage such as diabetic macular edema (DME) and choroidal neovascularization (CNV). Several studies reported good reproducibility of commercially available Time Domain OCTs. Few studies have investigated the role of OCT in the diagnosis and management of CNV. These studies involve relatively small numbers of patients. To date no proper reproducibility studies has been conducted in exudative AMD. With the increasing importance of OCT in patient care and the common use of OCT as a key outcome measure in recent clinical trials of exudative AMD, it is important to determine the reproducibility of OCT measures in a large population of patients with CNV. Methods: In the current study, we report the reproducibility of retinal thickness measurements made with the Zeiss OCT3 in 100 patients with exudative AMD. Reproducibility is assessed for retinal thickness in the central subfield, center point thickness (measured using the automatic software algorithm), and foveal thickness measured manually. Furthermore particular changes in retinal morphology, such as cystoid abnormality, subretinal fluid, or presence of pigment epithelial detachment are analysed.These findings will be compared with the currently available litterature

Reproducibility of Macular Thickness and Volume Using Zeiss Optical Coherence Tomography in Patients with Diabetic Macular Edema

To evaluate optical coherence tomography (OCT) reproducibility in patients with diabetic macular edema (DME). Prospective 1-day observational study. Two hundred twelve eyes of 107 patients with DME involving the macular center by clinical examination and OCT central subfield thickness of > or =225 microm. Retinal thickness was measured with the OCT3 system, and scans were evaluated by a reading center. Reproducibility of retinal thickness measurements was assessed, and 95% confidence intervals (CIs) for a change in thickness were estimated. Reproducibility of OCT-measured central subfield thickness. Reproducibility was better for central subfield thickness than for center point thickness (half-width of the 95% CI for absolute change, 38 microm vs. 50 microm, and for relative change, 11% vs. 17%, respectively; P<0.001). The median absolute difference between replicate measurements of the central subfield was 7 microm (2%). Half-widths of the 95% CI for a change in central subfield thickness were 22, 23, 33, and 56 microm for scans with central subfield thicknesses of <200, 200 to <250, 250 to <400, and > or =400 microm, respectively. When expressed as percentage differences between 2 measurements, half-widths of the 95% CI for a change in central subfield thickness were 10%, 10%, 10%, and 13% for scans with central subfield thicknesses of <200, 200 to <250, 250 to <400, and > or =400 microm, respectively. We were unable to identify an effect on reproducibility of central subfield measurements with respect to the presence of cystoid abnormalities, subretinal fluid, vitreomacular traction, or reduced visual acuity. Reproducibility was better when both scans had a standard deviation (SD) of the center point of <10.0% (half-width of the 95% CI for change, 33 microm vs. 56 microm; P<0.001). Reproducibility is better for central subfield thickness measurements than for center point measurements, and variability is less with retinal thickness when expressed as a percent change than when expressed as an absolute change. A change in central subfield thickness exceeding 11% is likely to be real. Scans with an SD of the center point of > or =10.0% are less reproducible and should be viewed with caution when assessing the validity of an observed change in retinal thickness in patients with DME.

Repeatability and Reproducibility of Fast Macular Thickness Mapping With Stratus Optical Coherence Tomography

To determine the repeatability and reproducibility of retinal thickness measurements with the fast macular thickness mapping protocol of Stratus optical coherence tomography. Ten eyes of 10 healthy subjects and 15 eyes of 15 diabetic patients with clinically significant macular edema (CSME) underwent 2 scanning sessions before and after pupil dilation during the same visit by 2 experienced examiners. Healthy subjects also received a third scanning session during a second visit. Repeatability and reproducibility for the foveolar center and for each of 9 Early Treatment of Diabetic Retinopathy Study (ETDRS)-like regions were calculated by their repeatability and reproducibility coefficients and intraclass correlation coefficients. The coefficients of repeatability were less than 8% in healthy subjects and less than 9% in patients with diabetes and CSME. The reproducibility coefficients were less than 10% and 11% in healthy subjects and diabetic patients with CSME, respectively. There was no significant difference between scans acquired by different observers or during different visits. The intraclass correlation coefficients were always greater than 0.80 and 0.98 in healthy subjects and diabetic patients with CSME, respectively. Average +/- SD thickness was found to be 223 +/- 14 and 404 +/- 108 mum for the central ETDRS-like region in healthy subjects and diabetic patients with CSME, respectively. With the fast macular thickness mapping protocol of Stratus ocular coherence tomography, our results indicate that retinal thickness measurements in dilated and undilated eyes of healthy subjects and diabetic patients with CSME are repeatable and reproducible.

COMPARISON OF FOVEAL THICKNESS MEASURED WITH THE RETINAL THICKNESS ANALYZER AND OPTICAL COHERENCE TOMOGRAPHY

To assess and compare the reliability and reproducibility of retinal thickness measurements for the retinal thickness analyzer (RTA) and optical coherence tomography (OCT) in normal and edematous retina. The authors measured the foveal thickness of 21 normal eyes and 9 eyes with macular edema with both methods in random order. With the RTA, the fovea was measured 10 times; with the OCT, six scans (one horizontal and five vertical cross-sections) of the fovea were obtained. Mean foveal thickness of normal eyes measured 153 microm with OCT and 181 microm with RTA (median for both methods 150 microm). Coefficients of variation (CV) within the same subjects were 10% (OCT) and 9% (RTA) reducing to 9% (OCT) and 7% (RTA) when scans were repeated only five times for both methods. The RTA, however, yielded an interpatient CV of 33% (OCT 17%), which was caused by several falsely high readings in normal individuals. In eyes with retinal thickening the OCT measured a mean of 324 microm with 15% intra- and 58% interpatient CV. The RTA yielded a mean of 403 microm with CV of 18% and 73%, respectively. Both methods yield reproducible measurements of foveal thickness in normal individuals and individuals with macular edema. However, falsely high measurements may occur with the RTA, reducing its reliability as compared to the OCT.

Reproducibility of Retinal Thickness Measurements in Normal Eyes Using Optical Coherence Tomography

To determine the reproducibility of retinal thickness measurements in normal eyes using optical coherence tomography (OCT). Multiple 3.20-mm vertical cross-sectional images through the center of fixation of consecutive patients with normal results on ocular examinations were obtained. Each image was divided into seven 320-micron segments. Regional retinal thicknesses for each section were measured using both the manually assisted (requiring observer localization of reflectivity peaks) and the automated modes (observer-independent measurement) of the computer software. Eighteen right eyes were studied. The mean coefficient of variation was less than 10% for all locations using the manually assisted method (average standard deviation less than 17 microns [range 9 to 16 microns]). The automated method was less reliable, with a coefficient of variation greater than 10% for locations within 500 microns of fixation. Automated measurements at fixation were the least reproducible because of poor internal limiting membrane reflectivity. OCT is capable of reproducible measurement of retinal thickness in normal eyes. Computer-driven, automated measurement of retinal thickness within 500 microns of fixation needs to be refined and its reproducibility reassessed in this region.