Comparison of OCTA Axial Profiles in Healthy Eyes and Eyes with Diabetic Retinopathy

Abstract

Purpose : While in standard transverse en-face image analysis, optical coherence tomography angiography (OCTA) is averaged over predefined retinal vascular slabs, in axial OCTA analysis, the signal is averaged over the transverse directions, and the resulting axial profiles are subsequently analyzed in depth. Axial profile analysis may provide a more sensitive method for detecting microvasculature changes with disease at different depths even in high-speed OCT acquisitions at lower transverse resolution (preserving the high original OCT resolution axially). In this study, we sought to compare axial profiles in healthy eyes with eyes afflicted with diabetic retinopathy (DR).

Methods : The study cohort includes 17 healthy eyes and 18 eyes with DR. Among the 18 DR eyes, 4 had mild non-proliferative (NP) DR, 9 had moderate NPDR, and 5 had diabetic macular edema (proliferative (P) DR or NPDR). OCTA macular images were captured with the Spectralis OCT2 (Heidelberg Eng.) using a scan pattern size of ~5.8mm x 5.8 mm (20° x 20°; 512 x 512 pixels). Axial signals were quantified from specific retinal layers: NF - nerve fiber, GC - ganglion cell, IP - inner plexiform, IN - inner nuclear, and OP - outer plexiform. Axial signals were quantified within fovea-centered concentric rings with radii 1.5°- 2° (paracentral), 3°- 3.5° (pericentral), and 4.5° - 5° (peripheral).

Results : Fig.1 compares axial profiles in eyes from healthy subjects and DR patients. Fig. 2 compares DR subcategories. Compared to healthy eyes, overall axial signal reduction was observed in DR eyes and DR subcategories. Blunting of axial signal peaks in GCL and in IPL-INL (intermediate capillary plexus) in paracentral ring was observed in DR eyes compared to healthy eyes. Additionally, both intermediate and deep (INL-OPL) peaks were blunted in DR eyes in pericentral and peripheral rings. Significant differences were not observed among eyes with different DR stages.

Conclusions : Axial profile analysis can distinguish normal and DR eyes, providing new insights into disease pathophysiology. The parafoveal OCTA signal was attenuated in DR eyes at multiple flow layers. These observations warrant further investigation with a larger study cohort.

This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.

 

Fig. 1. Comparison of axial profiles from healthy (green) and DR (red) eyes.

 

Fig. 2. Comparison of axial profiles from healthy (green), mild NPDR (cyan), moderate NPDR (blue), and diabetic macular edema (PDR or NPDR) (black) eyes.