Surgery to remove cataracts, which causes the normally clear lens of the eye to become cloudy, can restore vision almost immediately. New research suggests that cataract surgery may also have another benefit: a reduced risk of Alzheimer’s disease and other forms of dementia.
For the study, scientists looked at 3,038 men and women with cataracts who were 65 years of age or older and did not have dementia at the time of diagnosis. Of these, 1,382 had cataract surgery, and the rest did not. All subjects were part of a decades-long memory study that had followed them for decades.
The researchers found that the overall risk of dementia was 29% lower in those who had cataract surgery compared with those who did not.
The researchers also looked at glaucoma surgery, another type of eye surgery that doesn’t restore vision but can help prevent vision loss. It did not affect the risk of dementia.
The research, in JAMA Internal Medicine, adjusted for age at first diagnosis of cataracts as well as various risk factors for dementia, including low education, smoking, high body mass index and increased blood pressure. The only trait that had a greater impact on dementia risk than cataract surgery was that not carrying the APOE-e4 gene was associated with an increased risk of Alzheimer’s disease.
“The authors were incredibly thoughtful in how they approached the data and considered other variables,” said Dr. Nathaniel A. Chin, assistant professor of medicine at the University of Wisconsin, who was not involved in the study. . “They compared cataract surgery with surgery that did not improve vision – glaucoma surgery – and controlled for many important confounding variables.” Dr. Chin is medical director of the Wisconsin Center for Alzheimer’s Research.
Lead author, Dr. Cecilia S. Lee, associate professor of ophthalmology at the University of Washington, said: “We were amazed at the magnitude of this effect.
The authors note that this is an observational study that does not demonstrate cause and effect. But they suggest that this may be the best kind of evidence that can be obtained, since a randomized trial in which only a few people are allowed to have cataract surgery would be both practical and ethically impossible. virtue.
“People can say that people who are healthy enough to have surgery are generally healthier, and therefore less at risk of developing dementia in all cases,” Dr. Lee said. “But when we found no association in glaucoma surgery, it supported the idea that it was not just eye surgery, or health enough for surgery, but the specific impact for cataract surgery.”
The findings reinforce previous research showing that vision loss – as well as hearing loss – are important risk factors for cognitive decline. For example, people who have difficulty seeing or hearing may withdraw from activities such as exercise, social interactionread or Pursuit of wisdomAll of which are associated with a lower risk of dementia.
But the researchers also suggest a possible physiological mechanism. They write in the paper that the visual cortex undergoes changes with loss of vision, and impaired vision can reduce brain input, leading to brain shrinkage, which is also a risk factor for dementia. intellectual impairment. At least an earlier study noticed an increase in brain gray matter volume after cataract surgery.
While the exact mechanism of the benefits of cataract surgery is still unknown, Dr. Lee said it is not surprising that some of the changes we see in the eye may reflect other processes. process in the brain. “The eye is intimately connected with the brain,” he said. “Eyes develop in utero from the brain and share nerve tissue. The eye is in the process of coming out of the brain first. ”
Dr Chin says the most important question for him going forward is what this means for doctors and patients. Doctors in primary care clinics or those dealing with memory need to do more screening for vision loss, he said. “We can talk to people about improvements. potential brain health with cataract surgery as well as the need to address vision throughout a person’s lifetime. a means of cognitive protection. ”
https://www.nytimes.com/2022/01/24/well/mind/cataract-surgery-dementia.html Cataract surgery can reduce your risk of dementia