Abstract
Purpose :
To identify intraretinal microvascular abnormalities (IRMA) in nonproliferative retinopathy diabetic patients with early treatment diabetic retinopathy study (ETDRS) severity levels 43, 47 and 53.
Methods :
Sixty eyes from 60 patients with type 2 diabetes were imaged with seven-field Color Fundus Photography (CFP) using a Topcon TRC-50DX camera (Topcon Medical Systems, Tokyo, Japan), Optos California (Optos plc, Dunfermline, UK) ultra-widefield fundus fluorescein angiography (UWF-FFA), swept-source optical coherence tomography angiography (SS-OCTA) (PLEX® Elite 9000, ZEISS, Dublin, CA, USA), spectral-domain (SD)-OCTA (CIRRUSTM HD-OCT 5000 Angioplex, Zeiss, Dublin, CA, USA) and SD-OCTA AngioVue (Optovue RTVue, Optovue Inc, CA, USA).
A free open-source image editing software tool, Gimp (version 2.10), was used to annotate regions suspicious of IRMA using images from different image modalities. IRMA were first identified in the 50° Field 2 CFP and then searched in UWF-FFA early phase image, in SS-OCTA PLEX Elite (Angiography 15x15 mm acquisition protocol), SD-OCTA Cirrus Angioplex (Angiography 6x6 mm) and SD-OCTA AngioVue (HD Angio Retina 6x6 mm). For OCTA analysis, IRMAS were defined as capillary tortuosities covering a minimum circular area of 300 µm calculated to correspond to ETDRS standard photo 8A.
Results :
In OCTA images, IRMAs were identified in both superficial (SCP) and deep capillary plexuses (DCP). In sixty eyes, CFP detected 91 IRMAs in the midperiphery. SS-OCTA PLEX Elite detected IRMAs in similar number to UWF-FFA but only up to the midperiphery with SS-OCTA detecting 152 and UWF-FFA detecting 169. However, UWF-FFA is capable of detecting also IRMAs in the far periphery (n=234), showing that IRMA are mainly located in the far periphery. Finally, Cirrus AngioPlex and AngioVue, identified in both plexuses 24 and 27 IRMAs, respectively, in the posterior pole.
Conclusions :
Identification of IRMAS in eyes with moderate-severe nonproliferative diabetic retinopathy is better achieved by UWF-FFA and it covers the midperiphery and far periphery. However, nearly similar numbers of IRMAs can be detected by non-invasive imaging using SS-OCTA PLEX Elite, with the limitations that this analysis is restricted to the posterior pole and midperiphery.
This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.