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L. Seibold, N. Mandava, M. Y. Kahook; Comparison of Spectral Domain Retinal Nerve Fiber Layer Thickness and Agreement with Time Domain Optical Coherence Tomography. Invest. Ophthalmol. Vis. Sci. 2010;51(13):240.
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© ARVO (1962-2015); The Authors (2016-present)
To compare the retinal nerve fiber layer thickness (RNFL) measurements between three different spectral domain optical coherence tomography (OCT) instruments (Spectralis - Heidelberg Engineering, Heidelberg, Germany; Cirrus - Carl Zeiss Meditec, Dublin, CA; Optovue - Optovue, Inc., Fremont, CA) and time domain OCT measurements (Stratus - Carl Zeiss Meditec, Dublin, CA).
80 normal eyes (40 patients) were scanned for RNFL thickness measurements using each of the four OCT instruments by a single experienced operator on the same day. All eyes underwent a baseline examination with visual field testing to rule out evidence of glaucoma or other ocular disease. Student paired t testing, Pearson's correlation coefficient, and Bland-Altman graphs were used for statistical analysis.
Average RNFL thickness determined by each of the 3 spectral domain OCT machines had a high correlation with measurements by Stratus (r = 0.78 Spectralis, r = 0.90 Cirrus, r = 0.92 Optovue), although each was significantly different than Stratus. The average RNFL thickness (mean ± standard deviation) was 110.64 µm ± 13.0 for Stratus, 106.79 µm ± 14.55 for Spectralis, 99.38 µm ± 11.71 for Cirrus, and 112.95 µm ± 13.48 for Optovue. The mean differences between each spectral domain instruments and Stratus were 3.85 µm ± 9.31 (p<0.01) for Spectralis, 11.25 µm ± 5.57 (p<0.01) for Cirrus, and -2.31 µm ± 5.26 (p<0.01) for Optovue. There were also significant (p≤0.01) differences in quadrant RNFL thickness from each spectral domain instrument and Stratus (Spectralis: temporal -3.34 µm, inferior 6.91 µm, nasal 10.69 µm; Cirrus: temporal 10.48 µm, inferior 11.47 µm, nasal 13.49 µm, superior 9.54 µm; Optovue: temporal -13.25 µm, inferior -4.23 µm).
There is excellent correlation between time domain OCT and each of the three spectral domain OCT instruments. However significant differences in RNFL measurements do occur between each instrument. This study confirms previous reports that Cirrus produces RNFL measurements thinner than Stratus. New findings in this study include that RNFL thickness is significantly higher when using Optovue and significantly lower with Spectralis when compared to Stratus OCT. Clinicians should be aware of the relationship between Stratus RNFL measurements and each of the new spectral domain OCT measurements in the normal population.
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