J Korean Ophthalmol Soc.  2009 May;50(5):710-716. 10.3341/jkos.2009.50.5.710.

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

• Oh SB
• Cho WB
• Moon JW
• Kim HC

• KMID: 2212304
• DOI: http://doi.org/10.3341/jkos.2009.50.5.710

Abstract

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.

Keyword

Coefficient of variation; Intraclass correlation coefficient; Spectral domain OCT; Time domain OCT; Within-subject standard deviation

MeSH Terms

Tomography, Optical Coherence

Figure

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  Figure 1. Bland‐Altman plots of foveal thickness measurements obtained by Stratus OCT and Spectralis OCT. Solid line indicates the average mean difference, while dotted lines delineates the 95% confidence limits of agreement.

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  Figure 2. Bland‐Altman plots of total macular thickness obtained by Stratus OCT and Spectralis OCT. Solid line indicates the average mean difference, while dotted lines delineates the 95% confidence limits of agreement.

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  Figure 3. Bland‐Altman plots of total macular volume obtained by Stratus OCT and Spectralis OCT. Solid line indicates the average mean difference, while dotted lines delineates the 95% confidence limits of agreement.

Reference

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