Cataract Surgery: It Is More Than Just Your Vision That Improves

The track record of cataract surgery improving vision is long and well established. But there is also an intriguing line of research that suggests that one of the most common ophthalmologic surgeries may also have cognitive benefits.

A review published earlier this month in the journal Ophthalmology showed that cataract surgery was associated with a 25% reduced risk of long-term cognitive decline compared with not having the surgery. Lead author Brian Sheng Yep Yeo, M.B.B.S., of the Yong Lee Lin School of Medicine at the National University of Singapore and his colleagues found that the benefit was present for a variety of cognitive outcome and held up in various sensitivity analyses.

They also found that cataract surgery was associated with a 4% improvement in short-term cognitive test scores.

Yeo and his colleagues conducted their review by searching the PubMed, Embase and the Cochrane Library databases from inception through Oct. 11. They identified 24 articles comprising almost 560,000 participants, of which 19 articles were qualitatively analyzed.

Yeo and a research team reported the results of a similar review of cognitive decline and hearing aids and cochlear implants in JAMA Neurology in December 2022. That study found that usage of “hearing restorative devices” was associated with a 19% decrease in the risk of long-term cognitive decline and, like cataract surgery, a smaller, 3% improvement in cognitive test scores in the short term.

It is not hard to find studies that suggest that cataract surgery has protective effects against cognitive decline. Last year, for example, Cecilia Lee, M.D., M.S., of the University of Washington, Seattle, and colleagues, reported the results of an analysis in JAMA Internal Medicine using data from the Adult Changes in Thought study, an ongoing study of members of Kaiser Permanente Washington. Study participants were 65 years of age or older and cognitively normal when they were enrolled and then followed every year other year until they developed dementia. Just over 3,000 individuals who had a cataract diagnosis were included in the analysis. The researchers found that cataract extraction was associated with a 30% lower risk of dementia compared with people who didn’t get surgery. They made statistical adjustments for years of education, self-reported White race, and smoking history and stratified by apolipoprotein E genotype, sex, and age group at cataract diagnosis.

These studies are identified to find associations; reasons for the associations are outside of what they can prove. Even so, researchers have some possible explanations. Untreated cataracts result in visual impairment that may lead to cortical atrophy because there is a lack of neuronal input. Cataract-related vision deficits may alter perceptions, which, in turn, affect cognitive abilities. There are also the indirect effects of poor vision, such as difficulty in navigating social situations that result in social isolation, and social isolation leads to cognitive deficits.

Some researchers have hypothesized that in some people, visual impairment and cognitive deficits may share some of the same causes, such as vascular changes that affect both the eye and the brain. The authors of a review about the “bidirectional relationship” between vision and cognition that was published in Ophthalmology in floated the notion that the beta amyloid deposits that many researchers believe cause Alzheimer’s may be implicated in vision loss.