Comparison of OCTA Axial Profiles in Healthy Eyes and Eyes with AMD

Abstract

Purpose : Eye disease analysis using en-face maps over predefined retinal vascular slabs in optical coherence tomography angiography (OCTA) has been a popular approach. However, such approach relies on high lateral resolution and is rather insensitive to decrease of OCTA signal (flow density) axially due to diseases. In contrast, axial profiles are averaged over the flow density in lateral directions which are then analyzed in depth and may be more sensitive to detect changes of microvasculature with diseases. The purpose of this pilot study is to compare axial profiles in healthy eyes and eyes with age-related macular degeneration (AMD).

Methods : The study cohort includes 19 eyes of young adults, 11 eyes of elderly adults, and 33 eyes of AMD patients. Among the 33 AMD eyes, 7 has intermediate AMD; 6 has geographic atrophy (GA); and 20 has macular neovascularization (MNV). OCTA macular images were captured with Spectralis OCT2 (Heidelberg Eng.) using scan pattern 3mm x 3mm (10° x 10°; 512 x 512 pixels). Axial signals were quantified from specific retinal layers (NF - nerve fiber, GC - ganglion cell, IP - inner plexiform, IN - inner nuclear, OP - outer plexiform) within fovea-centered concentric rings in radii 1.5°- 2° (paracentral) , 3°- 3.5° (pericentral), and 4.5° - 5° (peripheral).

Results : Fig.1 shows comparison of axial profiles in eyes from healthy young and elderly adults, and AMD patients. Fig. 2 shows that from AMD sub-category eyes. Blunting of axial signal peaks in GCL in paracentral ring and in IPL-INL (intermediate capillary plexus) in pericentral ring was observed in elderly and AMD eyes compared to young eyes. Both intermediate and deep (INL-OPL) peaks were blunted in AMD eyes compared to elderly eyes in paracentral ring. Significant differences were not observed in eyes with different AMD stages.

Conclusions : Axial profile analysis may reveal differences between healthy and diseased eyes, providing new insights into disease pathophysiology. AMD eyes show a reduction in parafoveal OCTA signal in intermediate and deep flow layers. These findings require replication in larger studies.

This is a 2021 ARVO Annual Meeting abstract.

 

Fig.1. Comparison of axial profiles from eyes of young (red) and elderly adults (blue), and AMD patients (yellow) in three fovea-centered concentric rings.

 

Fig.2. Comparison of axial profiles from eyes of different AMD sub-category diseases, i.e. intermediate AMD (green), GA (black), and MNV (cyan), in three fovea-centered concentric rings.