Vessel density metrics using swept-source OCTA discriminates severity staging of NPDR: The CHART Study

International audience

Inglés. Purpose : To test whether the location of a single or composite set of parameters evaluated with widefield swept-source optical coherence tomography angiography (SS-OCTA) and representing retinal capillary closure, can discriminate between advanced stages of non-proliferative diabetic retinopathy (NPDR).Methods : Ninety-five eyes from diabetic patients included in the CHART study (NCT04636307) with different severity stages of NPDR were evaluated on SS-OCTA (PLEX® Elite 9000, ZEISS, Dublin, CA, USA) using Angiography 15x15mm and Angiography 6x6mm acquisition protocols. These acquisitions were processed on the ARI portal using Macular Density v0.7.3.3 algorithm. 7-field photographs of the fundus were obtained for Early Treatment Diabetic Retinopathy Study (ETDRS) staging. Eyes were separated based on their ETDRS severity grade - ETDRS level 35 and ETDRS levels 43 to 47. SS-OCTA perfusion density (PD) and vessel density (VD) metrics were compared for each macular area.Results : Widefield SS-OCTA VD metrics show statistically significant differences between ETDRS 35 and ETDRS 43 to 47 severity levels in the mid-periphery, Extended Rings 1, 2 and 3 (3mm < radius < 7.5mm) in the deep capillary plexus (DCP, p < 0.001) and in the full retina (FR, p < 0.037). The VD of superficial capillary plexus (SCP) can discriminate between groups on the Extended Ring 3 (6mm < Radius < 7.5mm, p = 0.037).In the perifoveal area, Outer Ring (1.5mm < radius < 3mm), the DCP of the Angiography 15x15mm acquisitions is capable of discriminating between ETDRS groups while Angiography 6x6mm protocol is not. Although the digital resolution of the 15x15mm scan is worse than the 6x6mm scan, the former appears to be more sensitive to blood flow changes, considering its specific binarization threshold, thus providing better separation between ETDRS groups. PD show similar results to VD.Conclusions : Information of non-capillary perfusion in the mid-periphery of the retina obtained using widefield OCTA (PLEX Elite) is particularly relevant to identify NPDR progression and discriminate ETDRS 35 (mild NPDR) from ETDRS 43-47 (moderate and moderately severe NPDR).This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.