Macular thickness layers comparison between new High-Res OCT and Spectralis OCT2

Abstract

Purpose : A new high-resolution (High.Res) optical coherence tomography (OCT) prototype has been recently developed by Heidelberg Engineering (Heidelberg Engineering GmbH, Germany) with an axial resolution of 3 microns in tissue. The aim of this study was to compare retinal thickness layers between the High-Res OCT and the conventional Spectralis OCT2 in different macular sectors.

Methods : Cross-sectional, observational study. Consecutive healthy subjects without macular alterations and with refractive error lower than +/-3D were included. Dense volume OCT scan (20°x20°, 49 horizontal lines, automatic real time= 16) on High-Res OCT and Spectralis OCT2 were acquired for each eye included in the analysis. Corneal curvature data were collected to apply the magnification correction. Both eyes were included if meeting the inclusion criteria.
OCT volumes of all included eyes were automatically segmented using built-in software on Heidelberg Eye Explorer version 1.10.4.0.The macular region was divided in 3 concentric ETDRS rings: central, inner and outer ring: the resulting mean thickness of each subfield was compared between the two devices for all retinal layers.

Results : Overall, 76 eyes from 52 patients met the eligibility criteria and were included in our analysis. The mean age was 52.92 ±19,7 years (range: 20-88 years). Similiar central full retinal thickness was found between OCT2 and High-Res OCT (273.83± 21.86 vs 272.59 ± 20.89, p=0.249). Conversely, the inner and outer rings presented a significant difference between the two devices p<0.001 (338.64± 16.26 vs 341,03 ± 16.07) and 294,69 +- 14.32 vs 297.93 +-15.24 respectively).
Macular retinal nerve fiber layer (RNFL), ganglion cell layer (GCL), inner nuclear layer (INL), inner plexiform layer (IPL), outer nuclear layer (ONL), outer plexiform layer (OPL), and retinal pigment epithelium-Bruch’s membrane complex (RPE-BM) resulted significantly different between the High-Res OCT and OCT2 (p<0.05) in all macular sectors. No statistically difference was found in the central INL.

Conclusions : We found significant differences in terms of retinal layers thickness in most of the macular sectors. Despite the same segmentation algorithm, the higher axial resolution of the High-Res OCT seems to affect the thickness values of each retinal layer. The clinical impact of this new technology will need to be further clarified.

This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.