The retina is the innermost membrane of the eye which consists of several layers of membranes, and contains a number of nerve cells and photoreceptor cells to detect light, process and integrate visual information, and transmit it to the brain through the optic nerve.
When light hits the retina, it passes through the nerve cells and reaches the rod cells and cone cells. Rod cells enable us to see objects in black and white in a dimly lit room or in relatively low light conditions such as moonlight. Cone cells are cells that are only activated in relatively bright light, such as sunlight during the day, and are responsible for color vision.
The center of the retina is the fovea, which is where light from the center of the visual field reaches the retina. It can be said that this is the area with the greatest visual clarity. And there is an optic disc, which is the part where the optic nerve and the blood vessels distributed in the eye pass through the retina.
As there are no photoreceptor cells in the optic nerve disc, this area is called the blind spot, and light and objects are not perceived because light reaching the retina is not converted into nerve impulses.
As seen above, the retina is the innermost tissue of the eye and plays a very important role in detecting light, processing visual information, and transmitting it to the brain. As we age, the thickness of the retina becomes thinner, leading to poor vision. In addition, the theory that it is associated with a decline in cognitive function has been gradually raised in the academic world.
Recently, as studies supporting this theory have been published one after another at home and abroad, the retina is rapidly emerging as another main cause of dementia.
At the Society for Research in Vision and Ophthalmology’s 2023 Annual Meeting, Dr Robert Struyven, Center for Medical Image Computing, University of London, said, “Just as old age, high blood pressure and diabetes affect dementia, it is possible to prevent dementia through signals from the retina, predictable,” he said.
In other words, just as dementia can be delayed by early detection through lifestyle habits such as exercise and diet, dementia can be detected early by observing retinal thickness.
Before this, Seoul National University Bundang Hospital conducted a study to discover the relationship between retinal thickness and cognitive function in 430 elderly people every 5 years.
The research team were able to confirm that among the retinal layers, especially in the group where the thickness of the nerve fiber layer in the macula was thin, the nerve fiber layer thinned faster as time went by, and that the cognitive function declines suddenly.
In addition, elderly people whose retinal nerve fiber layer thickness was in the bottom 25% were five times more likely to suffer from dementia in the future than those in the top 75%.
Retinal diagnosis has a significant impact on the prevention and treatment of dementia. Early detection of cognitive decline can lead to early intervention and personalized treatment plans.
“Retinal diagnosis should be used as part of a comprehensive evaluation that includes other diagnostic tools,” said Dr. Struyben, because it also has limitations such as lack of standardization and ethical considerations.
