Correlation of average RNFL thickness using the STRATUS OCT with the perimetric staging of glaucoma

Objective@#To determine the correlation between average peripapillary retinal nerve fiber layer (RNFL) thickness measured with time domain optical coherence tomography (TD-OCT) in normal and glaucoma eyes. @*Methods@#This was a cross-sectional study of 281 eyes randomly selected from a previous study. Assessment of glaucomatous damage was done by glaucoma specialists who based their diagnosis on the visual field tests and optic disc photos, independent of OCT results. Eyes were classified into the following groups: normal, mild, moderate, or severe glaucoma. Severity of glaucoma was based on visual field abnormalities following a modified HodappAnderson-Parish criteria for staging. Average RNFL thickness of normal and glaucoma subgroups, as measured with STRATUS–OCT, were analyzed using single ANOVA test. Association between average RNFL thickness and severity of glaucomatous visual field loss was evaluated using the Pearson’s correlation coefficient analysis. @*Results@#183 eyes had no glaucoma; 27 had mild, 32 had moderate, and 39 had severe glaucoma. Mean average peripapillary RNFL thickness (μm) in the normal, mild, moderate, and severe glaucoma groups were 98.05(±13.46), 76.27(±11.79), 76.42(±16.01), and 56.17(±14.92) respectively. Significant differences were seen in the average RNFL thickness among the groups (P<0.05), except in eyes with mild to moderate glaucoma. A moderately strong correlation of -0.57 (P<0.05) was observed between average RNFL thickness and the stage of glaucoma. @*Conclusion@#TD-OCT showed moderately strong correlation between the average RNFL thickness and perimetric stages of glaucoma. Average RNFL thickness is a good parameter to discriminate normal from glaucoma eyes.

Repeatability and Agreement of Macular Thickness Measurement Using Time and Spectral Domain OCT in Diabetic Macular Edema

PURPOSE: To evaluate the repeatability of macular thickness measurements using time domain (TD) OCT and spectral domain (SD) OCT in diabetic macular edema. METHODS: In 42 eyes of 42 patients with diabetic macular edema, three consecutive macular measurements were performed with TD OCT and SD OCT, and measurements for macular thickness and total macular volume obtained by the two OCTs were compared. The within-subject standard deviation (Sw), coefficient of variation (CVw), and intraclass correlation coefficient (ICC) were calculated to assess repeatability, with agreement between measurements assessed with Bland Altman plots. The correlations were also evaluated via the Pearson's correlation coefficient. RESULTS: The Sw of TD OCT and SD OCT for foveal thickness, total macular volume were 29.67 micrometer/16.44 micrometer, 1.26 mm3/0.23 mm3, respectively, and were significantly lower in SD OCT. The ranges of the respective CVw and ICC values were 1.10-2.78%, 0.78~0.96 for TD OCT, and 0.29~0.94%, 0.92~0.99 for SD OCT. The SD OCT showed better repeatability for macular thickness measurements (all p< or =0.001). The 95% limits of agreement for foveal and total macular volume were 88.9 micrometer, 2.4 mm3, respectively. The Pearson's correlation coefficients of macular thickness and total macular volume between the two OCT methods were statistically significant (p=0.88-0.99). CONCLUSIONS: Although both OCTs proved reliable for macular thickness measurements in diabetic macular edema, SD OCT shows better repeatability than TD OCT. Although macular thickness measurements obtained from the two OCTs cannot be used interchangeably, there were statistically significant correlations between measurements obtained using the two OCTs.

The Comparison of Macular Thickness Measurements and Repeatabilities Between Time Domain and Spectral Domain OCT

PURPOSE: To compare macular thickness measurements obtained from time domain optical coherence tomography (TD-OCT) and 2 spectral domain (SD) OCTs and to evaluate their repeatability and agreement in normal subjects and diabetic macular edema patients. METHODS: Fifty-four healthy, normal subjects and 26 diabetic macular edema patients were participated in this study. In a randomly selected eye from each subject, two serial macular measurements were obtained from TD-OCT (Stratus OCT) and SD-OCTs (Cirrus HD-OCT, Spectralis HRA+OCT) by an experienced technician in random order. Nine areas of macular thickness map and repeatabilities obtained by the 3 OCTs were compared. RESULTS: In relative repeatability, SD-OCT showed better results overall compared to TD-OCT. Macular thickness was greatest in the Spectralis HRA+OCT in both normal subjects and diabetic macular edema patients, followed by Cirrus HD-OCT and Stratus OCT. In normal subjects, regardless of the type of comparison between the machines there was a statistically significant difference in all 9 areas. CONCLUSIONS: While the TD-OCT and the 2 SD-OCTs are reliable for macular thickness measurement, SD-OCT has better measurement repeatability compared with TD-OCT. Because macular measurements obtained from the 3 OCT systems cannot be interchanged, an effort should be made to standardize the measurement of each system.

Repeatability and Agreement of Macular Thickness Measurement Using Time Domain OCT and Spectral Domain OCT in Normal Subjects

PURPOSE:To compare the repeatability and agreement of macular thickness measurements using time domain (TD) optical coherence tomography (OCT) and spectral domain (SD) OCT in normal subjects. METHODS: Thirty-four normal subjects were included. Three consecutive macular measurements were taken with TD OCT and SD OCT. Total and regional macular thickness and total macular volume obtained by the two OCTs were compared. Within-subject standard deviation (Sw), coefficient of variation (CVw), and the intraclass correlation coefficient (ICC) were calculated to evaluate repeatability. The agreement was examined with Bland Altman plots. The correlation was also evaluated with Pearson correlation coefficients and multiple regression analysis. RESULTS: Sw for foveal thickness, total macular thickness, and total macular volume were 11.53 microm, 7.58 microm, and 0.48 mm3 for TD OCT and 6.69 microm, 2.55 microm, and 0.09 mm3 for SD OCT, respectively. The values for SD OCT were consistently lower, and this result was statistically significant. The range of the respective CVw and ICC values were 1.10~2.78% and 0.78~0.96% for TD OCT, and 0.29~0.94% and 0.92~0.99% for SD OCT, respectively. The SD OCT showed better repeatability for macular thickness measurements(all with p< or =0.001). The spans of 95% limits of agreement for foveal thickness, total macular thickness, and total macular volume were 67.94 microm, 29.01 microm, and 0.98 mm3, respectively. The Pearson correlation coefficient of foveal thickness, total macular thickness, and total macular volume between the two OCT's was statistically significant. CONCLUSIONS: Although both OCTs are reliable for macular thickness measurements, SD OCT shows better repeatability compared with TD OCT. Although macular thickness measurements obtained from the two OCTs can not be used interchangeably due to low agreement by different standards of measurement, there was a statistically significant correlation between the two OCT's.