Measurement of Foveal Retinal Thickness in Myopic Patients Using Different Display Modes on Optical Coherence Tomography: A Retrospective, Cross-Sectional Study.

Abstract

The aim of this work is to investigate the differences in the measurement of foveal retinal thickness in myopic patients between two display modes (1:1 pixel and 1:1 micron) on optical coherence tomography (OCT). Horizontal OCT line scan through the central fovea was used for manual measurement of foveal retinal thickness under the two display modes, and the values were compared using Wilcoxon signed-rank test. Correlations between the OCT image tilting angle (OCT ITA) and differences in OCT measurement were analyzed by Spearman's test. 127 participants with a median age of 28years, a median spherical equivalent (SE) of - 8.5 D, and a median axial length (AL) of 27.04mm. There were significant differences between the two display modes, with a median absolute difference (median relative difference) of 13.33μm (2.75%) for the central foveal thickness (CFT), 5.33μm (1.28%) for the Henle fiber and outer nuclear layer thickness (HFL + ONL), 3μm (6.47%) for the external limiting membrane to ellipsoid zone distance (ELM-EZ), and 4μm (8.77%) for the ellipsoid zone to retinal pigment epithelium distance (EZ-RPE) (all p < 0.05). The differences in foveal retinal thickness between the two display modes were significantly correlated with the OCT ITA (r = 0.732 for CFT, 0.561 for HFL + ONL, 0.642 for ELM-EZ, and 0.471 for EZ-RPE, all p < 0.05). Disparities between the two display modes were found in the manual measurement of foveal retinal thickness and correlated to the OCT ITA.