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O. J. Knight, R. T. Chang, W. J. Feuer, D. L. Budenz; Comparison of Retinal Nerve Fiber Layer Measurements Using Stratus and Cirrus OCT. Invest. Ophthalmol. Vis. Sci. 2008;49(13):4628. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
To determine the correlation between peripapillary retinal nerve fiber layer (RNFL) thickness measurements from Stratus time domain OCT and Cirrus spectral domain OCT for normals and glaucoma.
37 eyes of 37 patients with best-corrected visual acuity of 20/30 or better and no previous history of retinal disease were examined. Patients were recruited from the Bascom Palmer Eye Institute Glaucoma clinic and placed into Normal (n=4), Suspect (n=2), Early (n=16), Moderate (n=6), and Severe (n=9) Glaucomas based on clinical evaluation including cup-to-disc ratio, intraocular pressure, and visual field examination. Three sequential Cirrus Glaucoma Scans were taken for the selected eye (which was dilated), and immediately following three Stratus Fast RNFL Scans were obtained in the same eye. The Cirrus data was processed using Zeiss’ Optic Disk finding algorithm and RNFL segmentation software to extract a circular TSNIT profile (radius 1.73 mm), which is meant to emulate the same scan circle protocol found in Stratus Fast RNFL Scan.
The Pearson Correlation was highly correlated at 0.949. A Bland-Altman analysis of the data revealed that while Cirrus minus Stratus RNFL thickness differences ranged from -20 to +20 microns; these differences were significantly correlated with the averages of the two measurements (r=-0.69, p<0.001). For thinner RNFLs, Cirrus measurements tended to be larger than Stratus, while for thicker RNFLs, Stratus measurements tended to be larger than Cirrus.
RNFL thickness measurements in normal and glaucoma patients scanned with Stratus OCT correlate well with those from Cirrus OCT. However, adjustments may need to be made when following individual patients due to systematic differences in measurement values between the two instruments.
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