The Association of Biomarkers Detected by Optical Coherence Tomography Angiography (OCTA) of the Macula With Cognitive Functions in Patients With Type 2 Diabetes

OCTA represents a potential alternative for early detection of vascular abnormalities. OCTA algorithms generate an image, most commonly sized 3x3 mm or 6x6 mm, which is conventionally segmented into four zones: superficial retinal plexus, deep retinal plexus, outer retina, and choriocapillaris. OCTA enables monitoring of retinal vascular changes over time and allows early detection of microcirculatory abnormalities.

Cognition is the process by which the human brain receives information from the external environment, processes it, and transforms it into internal psychological activities for acquiring or applying knowledge. It includes memory, language, visuospatial skills, executive function, calculation, comprehension, and judgment. Various cognitive function tests have been developed through years of research. The most commonly used screening test for general cognitive function is the Mini-Mental State Examination (MMSE), while a more recent and sensitive tool is the Montreal Cognitive Assessment (MoCA). The MoCA test includes assessments of executive functions, high-level language abilities, and complex visuospatial tasks, making it suitable for detecting even mild cognitive dysfunction. Although these tests can assess a patient's cognitive level, they cannot confirm the presence of cerebral microvascular disease.

Numerous studies suggest a link between diabetes mellitus and cognitive impairment. While cognitive decline is not specific to diabetes, it is now recognized as a complication of the disease. In studies involving older populations, patients with diabetes demonstrated a higher risk of developing Alzheimer's disease and other forms of dementia. Since diabetes affects the entire vascular system, it is assumed that changes in the retinal microvasculature may reflect the general vascular condition of the body, including changes in the brain. Studies have shown that patients with advanced stages of DR often exhibit reduced cerebral blood flow, further contributing to cognitive decline.

Research also suggests that early interventional treatments, such as improved glycemic control and therapies aimed at enhancing vascular function, could reduce the risk of cognitive deterioration. There is growing evidence that changes in the retinal microvascular structure may reflect similar alterations in cerebral vascular structures, given that the retina and brain share common embryological and anatomical characteristics.

This study differs from previous ones as it focuses exclusively on the early stages of NPDR, including patients with diabetes who show no detectable changes on fundoscopy. This minimizes the risk of errors on the MoCA scale, since patients with reduced visual acuity due to macular edema or proliferative changes may score falsely low, leading to inaccurate assessments of their cognitive function.