Abstract
Purpose :
To determine the most reliable anatomical structure dimensions that can be used for size estimations on OCT.
Methods :
Six-mm horizontal central OCT images of 100 healthy eyes of 100 patients were captured using Heidelberg Spectralis OCT. Using the central horizontal scan to bisect the fovea, thicknesses of the ellipsoid zone (EZ), photoreceptor outer segment zone (POS), interdigitation zone (IZ), cone outer segment termination zone (COST), retinal pigment epithelium/Bruch membrane complex (RPE/Bruch) were manually measured at points 500 µm away from the center of the fovea in the temporal (T500) and nasal (N500) regions. Mean value and its standard deviation for each zone was calculated. Coefficient of variation ranks were used to determine the anatomical dimension that reveals the least variation among individuals.
Results :
Mean age of the participants was 59 ± 17 years. T500 region measurements of EZ, POS, IZ, COST and RPE/Bruch layers had a mean and standard deviation of 21 ± 2.6 µm, 11 ± 3.0 µm, 14 ± 3.1 µm, 7.4 ± 1.9 µm, 18.1 ± 4.8 µm, respectively. N500 region measurements revealed similar ranking with measurements of 21 ± 2.5 µm, 11 ± 2.5 µm, 14.2 ± 3.1 µm, 7.5 ± 2.0 µm, 18.1 ± 4.5 µm, respectively. Statistical analysis revealed low coefficient variation for EZ line thickness at both the T500 region (0.12 for EZ, 0.26 for POS, 0.22 for IZ, 0.25 COST, and 0.26 for RPE/Bruch membrane) and N500 region (0.12 for EZ, 0.22 for POS, 0.22 for IZ, 0.27 for COST, and 0.25 for RPE/Bruch membrane).
Conclusions :
The lowest coefficient variation value at both the T500 and N500 points is the thickness of the EZ line. Thus, EZ thickness can reliably be used to estimate the dimensions of anatomical structures detected on OCT scan.These findings could help standardize physician retinal layer analysis on OCT, which may enhance diagnostic accuracy.
This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.