Is there a connection between our eyes and brain? Researchers believe so. A University of Washington (UW) study proposes poor vision may be associated with Alzheimer’s disease. Learn more about why they believe protecting your vision is important for your eyes and brain health.* 

Why Did UW Researchers Investigate This?

Lead researcher and associate professor of ophthalmology at UW School of Medicine, Dr. Cecilia Lee, believes there are a lot of missed potential links between the aging eye and brain health. Since science does not fully understand what causes Alzheimer’s Disease, there are not many treatment options or preventive methods. 

However, earlier studies have linked age-related macular eye degeneration and diabetic retinopathy to the development of memory loss. “It wasn’t a subtle or small risk,” Lee adds. “That gave us the foundation to really go after the connection between the aging eye and the aging brain.”

What Were the Study’s Findings?

Researchers collected data from more than 5,500 patients who volunteered to participate. In this long-term project, patients were evaluated every two years for cognitive ability. 

Of the 3,038 patients who were older than 65 years old with cataracts or glaucoma, 853 developed dementia. Of that group, 504 patients developed it before or without cataract surgery, while 320 patients developed it after surgery. This is nearly a 30% decrease in the risk of developing dementia for those who had cataract surgery. 

Since this study was observational, many questions are still unanswered regarding the mechanisms between cataract surgery and dementia risk. 

Why May Eye and Brain Health be Connected?

The researchers found a significant association in decreased risk of dementia in patients who had cataract surgery, but not in those who had glaucoma surgery. Unlike glaucoma surgery, cataract surgery does restore vision. 

From this discovery, researchers developed a couple of hypotheses about why cataract surgery may help brain health: 

1.  Making Sense 

For one, when a person develops cataracts, their brains receive lower-quality sensory input due to the decline in vision.  Lee states, “So, a brain that’s not getting enough visual stimuli might be at a higher risk of developing dementia because it’s losing those neuronic connections.”

2.  Letting Light In

Another theory, Lee said, is that after cataract surgery, people are getting more blue light or a “better quality light that enters retinas.” Blue light has been found to help the retina cells in our eyes, which are associated with cognition. 

3. …With A Little Help from My Friends

The last hypothesis is related to improved vision allowing a person to be more social, physically active, and enjoy outside surroundings. All of these activities are shown to protect people from developing dementia. 

The strong results from this study should mark the beginning of many other related research opportunities. “There’s a tremendous amount of information we can get with noninvasive evaluation of the eye,” Lee said. “… People have said for many years that eyes are the windows to the brain or the soul. They really are.”

*Takahama, E. (2021, December 13). Cataract surgery associated with lower risk of dementia, University of Washington study finds. The Seattle Times. https://www.seattletimes.com/seattle-news/health/cataract-surgery-associated-with-lower-risk-of-dementia-new-university-of-washington-study-says/