Macular vessel density in diabetes and diabetic retinopathy with swept-source optical coherence tomography angiography

Purpose Previous studies on the association between macular vessel density (VD) and diabetic retinopathy had conflicting conclusions. This study assessed the alterations of macular VD, as well as other factors, in diabetic patients using swept-source optical coherence tomography angiography (SS-OCTA) in a large-scale sample from Chinese communities. Methods Patients with type 2 diabetes without history of ocular treatment were recruited from 2017 to 2018. The average and quadrant parafoveal vessel density (PVD) were obtained with a commercial SS-OCTA device (Triton, Topcan, Japan). Univariate and multivariate linear regression was used to analyse the correlation of PVD with diabetic retinopathy (DR), diabetic macular edema (DME), HbA1c, and other factors. Results A total of 919 patients were included in the final statistical analysis. After adjusting for other confounding factors, the DR patients had significantly lower average PVD (β= −1.062, 95% CI = −1.424 to −0.699, P < 0.001) in comparison with those without DR. In addition, the patients with mild DR or vision-threatening diabetic retinopathy (VTDR) also had significantly lower PVD (P < 0.001 for mild DR, and P = 0.008 for VTDR) compared with those without DR. Age and HbA1c were also significantly related to PVD measurements, as shown by multivariable linear regression. Participants with DME had a significantly lower average PVD and temporal PVD than those without DME (P < 0.05). Conclusions Reduced PVD was independently associated with more severe DR, older age, higher HbA1c level, and the presence of DME. These findings provide manifest evidence to suggest that macular vessel alterations play a role in the pathogenesis of DR.