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

BackroundNearly 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 MethodsIndividuals 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). ResultsNo 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 {beta} =-0.210 [p=0.014]; DCP: standardized {beta} =-0.275 [p<0.001]; FAZ: standardized {beta}=0.295 [p<0.001]). None of the retinal markers differed in individuals with or without WMHs and type 1 diabetes. ConclusionIn 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. Research insightsO_ST_ABSWhat is currently known about this topic?C_ST_ABSNearly all individuals with type 1 diabetes develop diabetic eye disease within 30 years following the diagnosis. We observed previously that one third of neurologically asymptomatic individuals with type 1 diabetes have cerebral microbleeds in routine brain magnetic resonance imaging. Cerebral microbleeds were more common among those with advanced forms of diabetic eye disease. What is the key research question?To investigate associations between markers of cerebral small vessel disease and metrics of optical coherence tomography angiography among individuals with type 1 diabetes. What is new?Vessel densities of the macula were smaller among those individuals with type 1 diabetes and cerebral microbleeds. Vessel densities were negatively and area of the foveal avascular zone positively associated with duration of diabetes. How might this study influence clinical practice?OCTA may aid cerebrovascular risk stratification among individuals with long-standing type 1 diabetes