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J. L. Hougaard, A. Heijl, S. Andersson, D. Bizios, B. Bengtsson; Effects of Quality Differences in Spectral Domain OCT on Glaucoma Diagnostics. Invest. Ophthalmol. Vis. Sci. 2010;51(13):255.
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© ARVO (1962-2015); The Authors (2016-present)
To examine whether differences in quality of spectral domain (SD) optical coherence tomography (OCT) images affect the diagnostic ability in glaucoma.
One eye in each of 117 healthy subjects and 84 glaucoma patients were included. The median field MD was -10.69 (-31.54 to -0.07) dB in the glaucoma patients. The peripapillary retinal nerve fiber layer (RNFL) thickness was assessed by the extracted circle data of the SD/Cirrus high definition (HD) OCT 200x200 optic disc cube scan. Two OCT images per eye were acquired in one session; one image with the acquisition settings controlled by the commercial software and the other manually controlled. OCT image quality was estimated by the signal strength (SS). In participants with a difference in SS between images the sensitivity and specificity was compared between the images with the better and worse SS and evaluated for full circle, ≥ 1 quadrant, and ≥ 1 clock hour OCT average RNFL thickness below the 5th percentile.
There was a difference in SS in 71 of the healthy subjects and in 46 of the glaucoma patients, 89% differed by 1 step better and 11% by 2 steps better on the SS scale. The RNFL thickness was on the average 1.4 microns thicker (p<0.0001) in the images with the better SS. The diagnostic sensitivity was not affected significantly by image quality, but specificity was 11% (CI95: 3 to 20%) better when applying the criterion of ≥ 1 clock hour below the 5th percentile.
The results suggest that small quality differences in SD OCT images have a significant effect on diagnostic performance.
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