Abstract
Purpose :
To assess the identification of intraretinal microvascular abnormalities (IRMAs) on different modalities and devices, in a cohort of nonproliferative diabetic retinopathy (NPDR) patients with Early Treatment Diabetic Retinopathy Study (ETDRS) severity levels 43, 47 and 53.
Methods :
Sixty eyes from 60 patients with NPDR were imaged by the Topcon TRC-50DX camera (Topcon Medical Systems, Japan) for color fundus photography (CFP), Optos California (Optos plc, UK) ultra-widefield fluorescein angiography (UWF-FA), swept-source optical coherence tomography angiography (SS-OCTA) (PLEX® Elite 9000, ZEISS, USA) and spectral-domain (SD)-OCTA (CIRRUSTM HD-OCT 5000 Angioplex, Zeiss, USA).
Annotations of IRMAs regions were performed manually by an experienced grader using the GIMP (version 2.10), an image editing software. Taking into consideration the area size of the IRMAs on the photo 8A of the ETDRS standard protocol, capillary tortuosities covering a minimum equivalent circular area of 300 µm of radius were categorized as IRMAs. IRMAs were firstly identified in the 50° Field 2 CFP and then searched in UWF-FA early phase image, in SS-OCTA PLEX Elite (Angiography 15x15 mm) and SD-OCTA Cirrus Angioplex (Angiography 6x6 mm).
Results :
When analysing the posterior pole of the retina (central 50°), CFP identified 104 IRMAs, whereas the PLEX Elite showed 133 IRMAs and the UWF-FA identified 203 IRMAs. When considering only the central retina, central 20°, CFP identified 20 IRMAs, PLEX Elite 7 IRMAs and UWF-FA 23. Finally, UWF-FA was able to identify 215 IRMAs in the mid and far periphery of the retina (50° to 130°) - Table 1. The IRMAs were only identified by the different imaging modalities in the superficial retinal capillary plexus.
When comparing the IRMAs identified in the posterior pole by PLEX Elite and by UWF-FA only 68 IRMAs are shown in the same location. For the central retina, only 4 IRMAs identified by PLEX Elite and 8 IRMAs identified by Angioplex are also shown in the UWF-FA images.
Conclusions :
Identification of IRMAs in eyes with moderate to severe NPDR is better achieved by UWF-FA while also covering the mid and far periphery. Categorization of IRMAs in each imaging modality is necessary for appropriate identification of these microvascular abnormalities which are particular relevant in the proliferative stage of diabetic retinopathy.
This abstract was presented at the 2024 ARVO Imaging in the Eye Conference, held in Seattle, WA, May 4, 2024.