PURPOSE: To understand the association between macular vessel density (VD) measurements and retinal nonperfusion (NP) and microaneurysm counts (MA#) in diabetic eyes.
METHODS: Same day optical coherence tomography angiography (OCTA) and ultrawide field fluorescein angiography (UWFFA) images were obtained from eyes of diabetic patients. Global NP and NP index (NPI), and specific posterior pole (PP, central 10mm diameter zone), mid-periphery (MP, 10-15mm) and far periphery (FP, >15mm) zones were evaluated. Retinal MA were manually annotated and quantified on UWFFA. OCTA 3x3 mm images were processed with projection artifact removal software (Angiovue ver 2017.1.0.151). Automated segmentation of superficial (SCP) and deep (DCP) capillary plexuses provided VD for the whole image and parafoveal macular quadrants.
RESULTS: A total of 54 eyes of 34 patients with mean±SD age 48.4±14.2 years, HbA1c 8.1±0.6%, diabetes duration 25.3±10.0 years, with 48.1% female, and 57.4% type 1 diabetes were imaged. DR distribution was mild 5 (9.3%), moderate 16 (29.6%), and severe 17 (31.5%) nonproliferative DR and proliferative DR 16 (29.6%). MA# and NPI increased with increasing DR severity (p<0.001). Local MA# correlated with NPI in the PP (r=0.77, p<0.001), MP (r=0.79, p<0.001) and FP (r=0.62, p<0.001). No relationship was found between global SCP VD and MA# or NPI. However, temporal (T) and inferior (I) SCP VD was correlated with PP NPI (T: r =-0.46, p<0.001, I: r=-0.36, p=0.008). There was an inverse association between global DCP VD and PP and MP MA# (MP: r=-0.49, p<0.001, PP: r=-0.38, p=0.005) as well as global NPI (MP: r-0.39, p<0.001, PP: r=-0.39, p=0.003) and FP NPI (r=-0.34, p=0.01). All DCP quadrants correlated with PP MA#. DCP-S, PP and MP while DCP-S correlated with FP MA#. DCP T and I VD were correlated with PP NPI (T: r=--0.41, p<0.002, I: r=-0.39, p=0.003) and T VD correlated with MP and FP NPI (r=-0.43, p=0.002 and r=-0.37, p=0.007).
CONCLUSIONS: These findings suggest that macular superficial versus deep vascular plexuses have differential associations with posterior versus peripheral MAs and nonperfusion in diabetes. Correlation with peripheral retinal pathology also varies between macular plexus quadrants. Further studies may provide further insight into how specific zones within OCTA macular scans reflect or predict disease activity beyond the posterior pole.
