Reproducibility of Macular Thickness Measurements Within Stratus OCT3 and Between OCT3 and OCT2

Abstract

Abstract: : Purpose: To determine the reproducibility of retinal thickness measurements (1) between duplicate OCT 3 macular scans, and (2) between scans with OCT3 and OCT2, in normal subjects and those with macular abnormalities. Methods: In 28 subjects having 13 eyes with normal maculas and 34 eyes with various macular abnormalities, duplicate scans were obtained using the Stratus optical coherence tomogram scanner and single scans with the OCT2 (Zeiss Humphrey Meditech). The 6 mm radial scan pattern, centered on the macula, was utilized for both, OCT3 combining all 6 B–scans into the "fast macular scan" requiring only one alignment, and OCT2 requiring individual alignment each. Assessment of scan quality examined accuracy of scan centration, correct detection of inner and outer retinal boundaries, and acceptable center point standard deviation (<=10% of center point measurement). Results:Scans were considered of adequate quality from OCT3 in 91.5% of scans, and from OCT2 in 59.6% of scans. Manual measurement of erroneous scans was possible for OCT3 in 5 of 5 such initial scans, and for OCT2 in 10 of 19. Center point average thickness (SD) between initial and duplicate OCT3 scans was 174 µm (32) vs. 178 µm (32) in normal eyes (p=0.15), and 345 µm (114) vs. 343 µm (116) in abnormal eyes (p=0.64); and between initial OCT3 and OCT2 scans was 174 µm (32) vs. 186 µm (29) in normal eyes (p=0.64), and 345 µm (114) vs. 333 µm (102) in abnormal eyes (p=0.96). The intraclass correlation coefficient (ICC) for Center point comparing initial OCT3 scans versus repeat OCT3 scans is 0.981(.965,.989). Comparing OCT2 and OCT3 scans, the ICC is 0.942 (.890,.970). Results for center subfield of the grid and retinal volume within the grid were also slightly better for comparisons within OCT3 than between OCT3 and OCT2.<BR Conclusions: Reproducibility within Stratus OCT3 is higher than that between OCT3 and OCT2, and the center point standard deviation (a critical quality metric) is lower for OCT3 than OCT2. A much higher percentage of OCT3 scans meet the criteria for adequate quality scans and would therefore set the standard for use in clinical trials.

Keywords: imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • clinical research methodology • macula/fovea