Cataract surgery may affect risks of developing dementia, study finds. Here’s why
As you get older, your senses tend to deteriorate slowly over time, including your sight, and the process could have debilitating effects on brain health, past research has shown.
A common age-related condition called cataracts is one of the many ways adults begin to lose their vision; it’s the leading cause of blindness worldwide, triggering symptoms such as blurry eyesight, sensitivity to light, trouble seeing at night and double vision.
The good news is that surgery to remove cataracts is widely available, although barriers to treatment still exist among certain communities.
Now, a new study reveals relatively healthy adults with cataracts or glaucoma who had cataract surgery were nearly 30% less likely to develop dementia later on — a benefit that lasted for at least 10 years after their procedure.
Researchers speculate sensory input gained from adults’ restored vision could explain the boost in brain health.
The study is observational, meaning cataract surgery is not guaranteed to lower dementia risks in everyone, but the findings add to experts’ understanding of the connection between age-related changes to the eyes and brain, potentially contributing to future therapies to slow or prevent dementia.
The study was published Dec. 6 in JAMA Internal Medicine.
“This kind of evidence is as good as it gets in epidemiology,” study lead researcher Dr. Cecilia Lee, associate professor of ophthalmology at the University of Washington School of Medicine, said in a news release. “This is really exciting because no other medical intervention has shown such a strong association with lessening dementia risk in older individuals.”
All of the 3,038 participants, who were ages 65 or older, were followed up with several times for an average of about 8 years.
Among the group, 853 people developed dementia — an umbrella term that describes a serious decline in cognition. The majority of cases were of Alzheimer’s disease, the most common cause of dementia.
About half of the study participants underwent cataract surgery throughout the study period, but none had dementia or history of cataract surgery when initially enrolled. They were a part of The Adult Changes in Thought study based in Seattle at Kaiser Permanente Washington. Data included in the research was collected between 1994 and 2018.
The study did not find out why cataract surgery lowers dementia risks, but researchers say improvements in sensory input following the procedure could have beneficial effects on the brain.
People with dementia and vision loss tend to struggle with disorientation, mobility, social isolation and communication. Such loss of activity can contribute to cognitive decline over time, but maintaining healthy eyesight could keep older adults as active as possible.
Exposure to blue light may also explain the association between cataract surgery and reduced dementia risks, researchers say.
“Some special cells in the retina are associated with cognition and regulate sleep cycles, and these cells respond well to blue light,” Lee said in the release. “Cataracts specifically block blue light, and cataract surgery could reactivate those cells.”
The latest data shows about 20.5 million people in the U.S. ages 40 and older have cataracts, according to the Centers for Disease Control and Prevention. That number was projected to grow to 30.1 million in 2020. Meanwhile, about 5.8 million have dementia.
Researchers said only participants’ first cataract surgery was evaluated, so it’s unclear if any subsequent surgeries influenced dementia risks. The majority of those in the study were white, so it’s unknown if the beneficial effects apply to other racial and ethnic groups.
