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M. Falcao, Z. Yehoshua, P. J. Rosenfeld, G. Gregori, W. J. Feuer; Comparison of Cirrus and Spectralis Spectral Domain OCT Measurements of Choroidal Thickness. Invest. Ophthalmol. Vis. Sci. 2010;51(13):2277. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
To compare choroidal images obtained using spectral domain optical coherence tomography (SDOCT) imaging with the Cirrus (Carl Zeiss Meditec, Dublin, CA) and Spectralis (Heidelberg Engineering, Germany) instruments.
45 eyes of 23 patients were imaged on the same day with both the Cirrus and Spectralis SDOCT. All patients were seen for routine care on the Retina Service of the Bascom Palmer Eye Institute and then enrolled in a prospective SDOCT protocol. Research consents were signed. Different macular pathologies were imaged including dry and wet AMD, diabetic macular edema and central serous retinopathy. Cirrus scans were obtained using the Cirrus 4.5 software which permits scan averaging. Scans could be averaged either 4 or 20 times. Spectralis SDOCT scans were performed using a 5x15-degree rectangle centered on the fovea with 7 B-scans averaged 100 times each. Inverted OCT frames were obtained with the same scan protocol except that the device was moved closer to the eye to enhance choroidal imaging. The foveal center was identified on representative B-scans and subfoveal choroidal thickness measurements were made using the calipers provided in the software. Failure rate was defined as the percentage of eyes in which choroidal thickness measurements were not obtained due to an inability to visualize the outer choroidal boundary.
Of the 45 imaged eyes, the upright Spectralis 5x15 rectangle could not be obtained in 2 eyes and the inverted Spectralis scan could not be obtained in 3 eyes due to poor cooperation. Failure rate for the Cirrus scans was 15/45 (33%) which was significantly lower than the failure rate for the upright Spectralis scans (23/45; 51%; p=0.021). Failure rate of the inverted Spectralis scans was 11/45 (24%) which was not statistically different from the Cirrus (p=0.29). Failure rate for the inverted Spectralis scans was significantly lower than the upright Spectralis scans (p<0.001). There were no statistically significant differences observed between the instruments when the choroidal thickness measurements were compared (Cirrus vs upright Spectralis, p= 0.3; Upright Spectralis vs Inverted Spectralis, p=0.3; Cirrus vs Inverted Spectralis, p=0.3).
There were no apparent differences in the failure rates and in the choroidal thickness measurements between the Cirrus averaged SDOCT scans and the Spectralis inverted images. Additional eyes need to be studied to confirm these observations, but it would appear that similar choroidal images and thickness measurements are obtained using either imaging modality.
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