Cataract surgery may reduce the risk of dementia

Surgery to remove cataracts usually causes the clear crystalline lens to become cloudy and can restore vision almost instantly. According to new research, cataract surgery may have other benefits as well. It is a reduced risk of Alzheimer’s disease and other dementia.

In this study, scientists examined 3,038 men and women with dementia-free cataracts aged 65 and over at the time of diagnosis. Of these, 1,382 had cataract surgery and the rest did not. All subjects were part of decades of memory studies that followed them for decades.

Researchers found that people who had cataract surgery had a 29 percent lower overall risk of dementia than those who did not.

Researchers have also focused on glaucoma surgery, another type of eye surgery that does not restore vision but helps prevent loss of vision. It did not affect the risk of dementia.

The Research in JAMA Internal MedicineAdjusted for various risk factors for dementia, such as age at the time of initial diagnosis of cataract, and years of education, smoking, high obesity index, and high blood pressure. The only feature that had a greater impact on the risk of dementia than cataract surgery was the lack of a gene called APOE-e4 that was associated with an increased risk of Alzheimer’s disease.

“The author was very thoughtful about how to approach the data and consider other variables,” said Dr. Nathaniel A. Chin, an assistant professor of medicine at the University of Wisconsin who was not involved in the study. I am. “They compared cataract surgery to surgery that does not improve vision (glaucoma surgery) and controlled many important confounding variables.” Dr. Chin is the medical director of the Wisconsin Alzheimer’s Disease Research Center.

“I was amazed at the magnitude of the impact,” said lead author Dr. Cecilia S. Lee, an associate professor of ophthalmology at the University of Washington.

The authors state that this is an observational study that has not proven its cause and effect. However, they are only allowed to undergo cataract surgery. Randomized trials are practically and ethically impossible, so this is the best kind of evidence achievable. It suggests that there may be.

“People may say that people who are healthy enough to have surgery are generally healthy, and therefore are unlikely to develop dementia in any case,” Dr. Lee said. .. “But if there is no relevance to glaucoma surgery, it supports the idea that it is healthy enough to undergo surgery, not just eye surgery, but the effect is unique to cataract surgery.”

Findings reinforce previous studies showing that Loss of sight ――Even Deafness — An important risk factor for cognitive decline.For example, a person who has difficulty seeing or hearing may withdraw from activities such as: exercise, Social interaction, Reading or Intellectual pursuit, All of these are associated with a low risk of dementia.

However, researchers have also suggested possible physiological mechanisms. They write that the visual cortex changes with loss of vision, and impaired vision can reduce input to the brain and lead to contraction of the brain, which is also a risk factor for dementia.at least Previous one study We found an increase in gray white mass in the brain after cataract surgery.

The exact mechanism of the benefits of cataract surgery remains unclear, but Dr. Lee said it is not surprising that some of the visible changes may reflect processes in the brain. .. “The eyes are very tightly connected to the brain,” he said. “The eyes develop from the brain into the uterus and share the same nervous tissue. The developing eye emerges from the forebrain.”

Dr. Chin said the most important question for him in the future is what this means for doctors and patients. Doctors in primary care clinics and those who treat memory need to be further screened for vision loss. “You can talk to people about the potential of cataract surgery to improve your brain health and the need to work on your vision throughout your life. A way to protect your cognition.”