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Jyotsna Maram, Muneeswar Gupta Nittala, Amir H Hariri, Srinivas R Sadda; Inter-scan repeatability of drusen and geographic atrophy measurements using spectral domain optical coherence tomography in eyes with Age related macular degeneration. Invest. Ophthalmol. Vis. Sci. 2017;58(8):31.
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© ARVO (1962-2015); The Authors (2016-present)
Optical coherence tomography (OCT)-derived geographic atrophy (GA) area has been proposed as a potential outcome measure in clinical trials, and OCT drusen volume in the central 3mm has been identified to be an important risk factor for late AMD. The purpose of this analysis is to evaluate the repeatability of drusen and GA measurements with two different OCT scan protocols in eyes with dry age-related macular degeneration (AMD)
Subjects with dry AMD who underwent SD-OCT (Cirrus HD-OCT, Carl Zeiss Meditec, Inc., Dublin, CA) imaging using two different scan protocols (two acquisitions of 512x128 and single acquisition of 200x200) at the Doheny Eye Centers-UCLA were included in this IRB-approved, study. Drusen area and volume (in 3mm and 5 mm circles centered on the fovea) and geographic atrophy area (in a central 5 mm circle) were measured using an FDA-cleared automated algorithm (Cirrus OCT Advanced RPE analysis). Inter-scan repeatability for drusen and GA measurements were analyzed using Intra class correlation (ICC) and student t-test.
Forty eyes of 20 AMD subjects were included. There was no significant difference in GA area between the two consecutive 512x128 volume scans (8.09 ± 4.25 vs. 7.99 ± 4.25, p = 0.47) with excellent agreement (ICC=0.98; 95% CI: 0.979 – 0.994). Similarly, drusen area (p = 0.38) and volume (p= 0.70) measurements also showed no statistically significant difference between the two 512x128 scans. There was, however, a significant difference for drusen volume in the central 3 mm between the 512x128 and 200x200 protocols (0.02 ± 0.03 mm3 vs. 0.015 ± 0.022 mm3, p = 0.02) (Table 1) – though drusen volume in the central 5mm and drusen area did not differ significantly between protocols. There was no statistically significant difference in GA area between the 512x128 and 200x200 protocols (7.99 ± 4.25 vs. 8.71 ± 4.83, p = 0.11) with excellent correlation (ICC=0.97; 95% CI: 0.948 – 0.988).
While it appears that both OCT macular cube protocols (512x128 and 200x200) yield somewhat similar and highly correlated measurements for GA, they do appear to differ with regards to drusen volume in the central 3mm. These differences will need to be considered when designing studies utilizing these protocols.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.
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