The eyes are said to be the windows to the soul. The eyes are also windows to the brain.
The eyes are well connected to the brain. The back of the eye, known as the retina, is like a film where images are formed before being sent to the brain via the optic nerve.
Therefore, in light of recent research suggesting a link between eye health and the risk of developing Alzheimer's disease and dementia, it seems important for older people, especially those over 65, to be aware of and maintain eye health.
Recently, there seems to be an established argument that the health of the retina can be a prognostic indicator of brain function, such as the ability to remember names and events, smell flowers, or recognize the faces of loved ones. There are several convincing studies that
A recent study examined retinal and brain tissue samples from 86 people over 14 years: normal donors, donors with mild cognitive decline, and donors with late-stage Alzheimer's disease. They found that people with cognitive impairment had significantly elevated levels of beta-amyloid and significantly reduced microglial cells (immune cells in the nervous system). Microglia repair damage, maintain neural networks, and repair damage.
Beta-amyloid is a degradation product of APP, a membrane protein that is broken down by enzymes into various products. Beta amyloid is a marker of both Alzheimer's disease and early cognitive decline.
Inflammation in distant regions of the retina may also be a predictor of cognitive decline.
Another study is using a new technology called optical coherence tomography (OCT) to reveal information about retinal thickness and predict an individual's likelihood of developing mild cognitive impairment or Alzheimer's disease.
OCT sends a beam of infrared light into the tissue of interest and combines the scattered light with a reference beam. There is an interference pattern used to generate a scan that gives the scattering properties of the tissue along the beam's path. A light beam moves along the tissue, producing a series of scans. This technique is used to measure blood flow to retinal blood vessels. A decrease in blood flow to the optic disc or papilla can be detected.
The optic disc can be seen as a round, yellowish-pink structure through an ophthalmoscope, which is used to view the retina, optic nerve, and blood vessels that supply the retina. The optic disc has no photoreceptors, so it is also known as the blind spot. (We are all reminded to check our blind spots when changing lanes on the road while driving.)
The optic disc is the entrance to the optic nerve as well as the blood vessels that supply the eye. Most commonly affected by glaucoma. In glaucoma, high fluid pressure compresses the optic disc. A branch of the internal carotid artery, the retinal artery and its tributaries supply blood to the retina and other parts of the eye.
A meta-analysis of 11 studies found that retinal thickness is reduced in Alzheimer's patients. In fact, the entire retinal layer is affected in these patients, and this abnormality cannot be attributed solely to aging. Although the biology of the degenerative processes that cause structural changes in the brains of Alzheimer's patients is still unknown, some scientists believe that the same degenerative processes also affect the neural layers of the retina.
Limitations of this study included the sample size not being large enough to generalize the results and the fact that seven different OCT instruments were used. If different types of equipment are used, the results will not be as reliable. I also wonder if 7 people using his 7 different instruments would introduce more bias into the results.
However, these findings serve as a strong case for further research and alert primary care clinicians to ask patients over the age of 45 about their eye health. If a healthcare professional suspects a problem, they can refer the patient to an ophthalmologist.
These are exciting times for eye research, as the advent of artificial intelligence and big data, combined with advanced imaging techniques, has led to the emergence of ophthalmology. This is a field that tries to find ocular biomarkers for other diseases in the body. But that's another column.
Syed Jamal teaches chemistry, biology, anatomy and physiology at the university level and researches phytoremediation and cancer biology. Kansas His Reflectors works to amplify the voices of those affected by public policy or excluded from public discussion through its opinion section. Click here for information, including how to submit a comment.
