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M. Swanic, D. Castro, C. Mattox, C. Krishnan; Comparison of Average Retinal Nerve Fiber Layer Thickness Obtained With Cirrus and Stratus OCT in the Evaluation of Glaucoma Patients. Invest. Ophthalmol. Vis. Sci. 2009;50(13):3337.
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© ARVO (1962-2015); The Authors (2016-present)
The advent of spectral domain (SD) OCT has allowed clinicians to rapidly obtain large quantities of high resolution retinal images when compared to time domain (TD) OCT. As physicians convert to this new technology it will be useful to know the level of correlation between SD and TD OCT in evaluating retinal nerve fiber layer (RNFL) thickness to manage glaucoma patients.
Between May 2008 and November 2008 141 eyes of 73 patients carrying the diagnoses of glaucoma or glaucoma suspect at the Tufts New England Eye Center Glaucoma Department underwent serial OCT evaluations of RNFL thickness by Cirrus (Software version 3.0) and Stratus OCT (Software version 4.01). RNFL data was collected on the same day of visit, and on the same machines, for both scans. Scans were done with 3.46 mm (Cirrus) and 3.4 mm (Stratus) ring diameter sizes by our trained photography staff. All scans had image quality ratings of 6 or greater and data was removed from analysis in 5 eyes in which this could not be obtained. Data was analyzed using Medcalc version 10.0.
The mean value of average RNFL thickness obtained with Stratus OCT was 87.2µ versus 78.6µ with Cirrus OCT. This resulted in a statistically significant difference of 8.6µ between the two machines (P<0.0001.) The correlation between data was high with an r value of 0.91 (P<0.0001). The data was placed on a Bland-Altmann plot which showed a mean difference between values of 8.7µ. 95% of differences in average RNFL thickness were found to be between -8.1µ and +25.4µ.
Data obtained from Cirrus (SD) OCT and Stratus (TD) OCT show high levels of correlation; however there is a statistically significant trend towards lower average RNFL values being obtained with the new Cirrus OCT. This difference may need to be considered by physicians who are switching to this new technology when making management decisions for glaucoma and glaucoma suspect patients
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