People Who Have Undergone Cataract Surgery Less Apt to Develop Alzheimer’s, Study Finds

Cataract surgery removes and replaces a cloudy lens that is causing vision problems. As we get older, this is more apt to be a problem, as about 50% of adults over 80 have either had cataracts or had the surgery. Among the benefits are being able to see things more clearly, having less glare when you look at bright lights, and being able to differentiate between colors. A new study finds that it may also reduce your risk of developing Alzheimer’s disease.

Researchers at the University of Washington examined a population of more than 3,000 seniors to determine if cataract surgery has any impact on dementia risk. Their findings, recently published in JAMA Internal Medicine, show that seniors who had undergone cataract surgery were 30% less apt to develop dementia to those who had not. This benefit, which lasted for at least ten years post-surgery, may provide more insight into a disease that has no cure and limited treatments.

Dr. Cecilia Lee, lead researcher and associate professor of ophthalmology at the University of Washington School of Medicine, says, “This kind of evidence is as good as it gets in epidemiology. This is really exciting because no other medical intervention has shown such a strong association with lessening dementia risk in older individuals.”

To conduct the study, Lee’s team used data from the Adult Changes in Thought (ACT) study, which followed more than 5,000 people over the age of 65 at Kaiser Permanente Washington. Researchers zeroed in on cognitively healthy participants who had been diagnosed with a cataract or glaucoma but had not had surgery when they first volunteered for the study.

After an average follow-up period of 7.8 years, 853 of 3,038 participants had developed dementia. Of those cases, 709 had Alzheimer’s. At the same time, 1,382 participants – or 45% – had undergone cataract surgery. After adjusting for possible confounding factors, the researchers found that those who had undergone the surgery in either eye were roughly 30% less likely to develop any form of dementia for at least ten years after the fact. This was especially true with Alzheimer’s.

While the reason for this link was not determined, the team theorizes that the higher quality sensory input the surgery produces may have played a role.

Dr. Eric B. Larson, co-author and principal investigator of the ACT study, says, “These results are consistent with the notion that sensory input to the brain is important to brain health.”

Dr. Lee says the decreased risk may also be due to people getting more blue light after the surgery.

She explains, “Some special cells in the retina are associated with cognition and regulate sleep cycles, and these cells respond well to blue light. Cataracts specifically block blue light, and cataract surgery could reactivate those cells.”

The researchers acknowledged some limitations of the study, including that unmeasured or residual factors could play a role in the findings and that the results may not be applicable to everyone because the majority of participants were white. However, the team notes that if their findings are confirmed in future studies, cataract surgery may be beneficial for older people at risk of dementia.