Structural and metabolic retinal changes associated with mild cognitive impairment in type 2 diabetes

Type 2 diabetes is associated with cognitive impairment and a twofold increased risk of dementia compared to age-matched individuals without diabetes. Given that the eye and the brain share similar embryologic origin and anatomical features the retina offers a unique “window” to the brain. In this study we wanted to determine whether there was a difference in retinal imaging-based neuronal and vascular markers in individuals with type 2 diabetes with or without minimal cognitive impairment (MCI). We included 134 persons with type 2 diabetes. Based on neuropsychological tests the prevalence of MCI was 28%. We performed 7-field color fundus photos, optical coherence tomography (OCT), OCT-Angiography and retinal oximetry in order to analysis retinal markers. In a multivariable cluster analysis, persons with MCI had significant thinner macular retinal nerve fiber layer and macular ganglion cell layer, and less venular oxygen saturation in the nasal quadrant compared to those without MCI. There were no differences in retinal vessel density, fractal dimension, width, tortuosity or OCT-A markers. People with type 2 diabetes and MCI demonstrate alterations in retinal structure and metabolism, suggesting non-invasive retinal markers may be useful to detect those at risk of cognitive dysfunction in people with type 2 diabetes.