Abstract
Purpose :
To evaluate retinal nonperfusion in eyes with moderate-severe nonproliferative diabetic retinopathy focusing on early treatment diabetic retinopathy study (ETDRS) diabetic retinopathy severity scale (DRSS) levels 43, 47 and 53.
Methods :
Sixty eyes from 60 patients with type 2 diabetes were included in the RICHARD study (NCT05112445). Eyes with DRSS levels 43, 47 and 53 were evaluated at baseline on Optos California (Optos plc, Dunfermline, UK) ultra-widefield fundus fluorescein angiography (UWF-FFA) and swept-source optical coherence tomography angiography (SS-OCTA) (PLEX® Elite 9000, ZEISS, Dublin, CA, USA). Skeletonized vessel density (SVD) and perfusion density (PD) metrics were evaluated in the superficial (SCP) and deep capillary plexuses (DCP). Seven-fields color fundus photographs using Topcon TRC-50DX camera (Topcon Medical Systems, Tokyo, Japan) were obtained for ETDRS DRSS and complemented with Optos California UWF-fundus photography. Optos California UWF-FFA was performed to calculate the total ischemic index.
Results :
The total ischemic index showed an increase in association with DR severity (DRSS43: 2.97±2.61; DRSS 47: 3.69±4.86; DRSS53: 3.95±2.80), but the differences between them did not reach statistical significance.
Widefield SS-OCTA SVD metrics showed statistically significant differences in the DRSS severity levels mainly in the DCP in the outer ring and midperiphery. Differences between DRSS 43 and 47 levels were found in the outer ring (SVD and PD: p=0.009). Furthermore, differences between DRSS 43 and 53 levels were found in the outer ring (SVD: p=0.013, PD: p=0.010) and midperiphery (SVD and PD: p=0.036).
Our results showed also a correlation between total ischemic index and OCTA metrics, i.e, increasing ischemic index with decreasing SVD and PD, for the midperiphery (Ext2: SVD in SCP: β=-0.314, p=0.023; in DCP: β=-0.286, p=0.040).
Conclusions :
Retinal capillary nonperfusion in eyes with DRSS levels 43, 47 and 53 is well identified by differences in the DCP in the outer ring and retinal midperiphery, using SS-OCTA. SS-OCTA 15x15mm acquisitions allow the discrimination between moderate-severe DRSS severity levels, which cannot be achieved by ischemic index determination obtained with UWF-FFA.
This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.