Researchers recently found that patients with mild cognitive impairment (MCI) and Alzheimer's disease (AD) experienced anatomical and functional retinal changes, including reductions in nerve fiber layer thickness, arterial blood flow, arterial vessel diameter and arteriovenous difference in oxygen saturation.

The study evaluated 47 patients with MCI or AD and 43 healthy age‐ and sex‐matched controls. Inclusion criteria were abnormal memory function and a Mini‐Mental State Examination (MMSE) score greater than 26 points for MCI patients and a diagnosis of mild to moderate AD and an MMSE score ranging from 20 to 26 points for AD patients.

Compared with healthy controls, MCI and AD patients had lower nerve fiber layer thickness (93.7±12.8µm vs. 99.1±9.0µm), arterial blood flow (9.3±2.4μl/min vs. 12.3±3.2μl/min), arterial vessel diameter (76.0±8.9µm vs. 80.6±8.0µm) and arteriovenous difference in oxygen saturation (20.4±5.1% vs. 23.5±4.0%) in the retina. The researchers did not report a difference in flicker response between the two groups.

“This indicates alterations in retinal oxygen metabolism in patients with neurodegenerative disease,” the study authors concluded in their paper.