Relations between retinal microvasculature by optical coherence tomography angiography and cerebral small vessel disease in individuals with type 1 diabetes

Backround: Nearly all individuals with type 1 diabetes develop diabetic retinopathy over time, known to relate to cerebral small vessel disease. We investigated associations between early vascular changes in the eye and brain by optical coherence tomography angiography (OCTA) and brain magnetic resonance imaging (MRI) in middle-aged, neurologically asymptomatic individuals with type 1 diabetes. Research Design and Methods: Individuals with type 1 diabetes (n=159, median age 48.0 years, diabetes duration 29.3 years, 53% female) and 49 healthy controls underwent clinical and biochemical assessments, brain MRI to evaluate cerebral microbleeds (CMBs) and white matter hyperintensities (WMHs), and macular 3x3 mm OCTA imaging to assess vessel densities of superficial (SCP) and deep (DCP) retinal capillary plexuses, and the area of the foveal avascular zone (FAZ). Results: No differences in OCTA parameters were observed between individuals with type 1 diabetes and healthy controls. However, SCP and DCP vessel densities (45.1% vs 46.5%, p=0.034, and 49.9% vs 52.9%, p<0.001, respectively), were smaller in individuals with type 1 diabetes with CMBs compared with those without. No such evidence was found for FAZ. In univariate linear regression models, SCP and DCP vessel densities were negatively associated with age, diabetes duration, blood pressure, kidney function (eGFR), number of CMBs, and WMHs. FAZ was related to diabetes duration, age of diabetes onset, and LDL cholesterol concentration. Of these, in multivariate models, diabetes duration remained associated negatively with vessel densities and positively with FAZ (SCP: standardized β =-0.210 [p=0.014]; DCP: standardized β =-0.275 [p<0.001]; FAZ: standardized β=0.295 [p<0.001]). None of the retinal markers differed in individuals with or without WMHs and type 1 diabetes. Conclusion: In middle-aged, neurologically asymptomatic adults with long-standing type 1 diabetes, lower SCP and DCP vessel densities were associated with cerebral microbleeds, suggesting OCTA may aid cerebrovascular risk stratification but not WMH assessment.