Carotid Disease and Retinal Optical Coherence Tomography Angiography Parameters in Type 2 Diabetes: The Fremantle Diabetes Study Phase II

OBJECTIVE To use optical coherence tomography angiography (OCTA) to determine whether retinal microvascular parameters are associated with carotid arterial disease in people with type 2 diabetes. RESEARCH DESIGN AND METHODS Participants (community-based) underwent detailed assessments including carotid ultrasonography and OCTA. Ultrasound images were assessed for mean intima-media thickness (IMT) and the presence of stenosis. OCTA image analysis provided measures of vessel density, foveal avascular zone (FAZ) area, blood flow areas, and retinal thickness. For each OCTA variable, the most parsimonious model was generated using generalized estimating equations, then ipsilateral and contralateral carotid disease–related variables were added to determine their significance. RESULTS A total of 474 eyes from 261 participants (mean ± SD age 72.0 ± 9.3 years, 57.1% males, median diabetes duration 15.4 years [interquartile range 11.1–22.4]) were analyzed. When carotid variables were added to the most parsimonious models, the ipsilateral natural logarithm of common carotid artery IMT (coefficient −2.56 [95% CI −4.76, −0.35], P = 0.023) and presence of any ipsilateral stenosis (−0.82 [−1.48, −0.17], P = 0.014) were statistically significantly associated with a lower parafoveal density in the deep capillary plexus. A mean bifurcation IMT ≥1 mm was associated with a decreased vessel density in the 300-μm ring surrounding the FAZ (coefficient −0.79 [−1.50, −0.08], P = 0.030)). Contralateral carotid disease–related variables were also significantly associated with retinal microvascular parameters. CONCLUSIONS This is the first study to show that carotid disease is an independent associate of retinal microvascular disease assessed by OCTA in type 2 diabetes. Appropriately intensive management of carotid disease may improve the retinal microcirculation.