Choriocapillaris flow deficit is associated with disease duration in type 2 diabetic patients without retinopathy: a cross-sectional study.

Background: Diabetes mellitus (DM) causes microvascular damage due to long-term hyperglycemia, even before the onset of retinal changes. We aimed to investigate the association between optical coherence tomography angiography (OCTA) metrics and disease duration in type 2 diabetic patients without retinopathy.

Methods: Eighty-two eyes of 82 type 2 diabetic patients without diabetic retinopathy (DR) were included. Choriocapillaris flow deficit (CC FD%), vessel density (VD), vessel length density (VLD) in the superficial (SVP) and deep vascular plexus (DVP) were calculated and compared between different sectors of the macula. Foveal avascular zone circularity (FAZc) was also calculated. Linear regression was used to study the association of each vascular parameter with disease duration both in a univariate and multivariate design adjusting for age, sex, Hb1Ac and arterial hypertension.

Results: CC FD% increased by 3.7, 2.3, 3.8 and 4.6% in the nasal, superior, temporal and inferior sectors per decade of disease duration, after adjusting for confounders. Mean values of VD and VLD in the SVP and DVP, as well as FAZc decreased with increased duration of DM, but the association was weaker. Only the VD in the superior and temporal sectors of the SVP were significant in the multivariate analysis (ß=-0.12 (95% CI -0.24 to -0.01) and - 0.13 (95%CI -0.25 to -0.002), respectively).

Conclusion: CC FD% is independently associated with disease duration in type 2 diabetes independent of the presence of clinical retinopathy. Further longitudinal studies are needed to investigate the role of choroidal changes in predicting DR onset in order to individualize screening protocols.