How to do it
- Book an eye test if your sight has got worse, or it's been years since the last one.
- If a cataract turns up, ask your eye doctor whether and when to remove it. That's their call with you.
- Decide on surgery for your sight. The dementia link is a possible extra, not a proven one.
What happens next
- Vision losson the risk list
In 2024 an expert panel added it to their list of dementia risk factors that can in principle be changed.
- Eye testfinds the cause
A cataract, a clouding of the eye's lens, is one thing it can find.
- Cataractremoved, or not
In one long study, having it removed went with less dementia than keeping it.
- Youa link, not proof
Another eye operation, for glaucoma, showed no link. That makes plain bias less likely; it doesn't prove the surgery did it.
Why it works
In 2024 an expert panel writing in The Lancet added vision loss to its list of dementia risk factors that can in principle be changed. Evidence: decent
In one long study, having a cataract removed went with about 29% less dementia over the following years than keeping it. Evidence: decent It's an observational study, so it shows a link, not that the surgery caused it. Evidence: decent Get your eyes checked for your sight. The rest is a possible extra.
The long readEvery step of the chain, each study with its numbers, and what's still unproven. 2 min read.
What happens next
This chain is a route to care, not brain areas.
Vision loss is on the list. The 2024 Lancet Commission lists 14 risk factors for dementia that can in principle be changed; vision loss was one of the two it added that year. Evidence: decent
An eye test finds the cause. A cataract, a clouding of the eye's lens, is one thing it can find. Evidence: solid
The cataract comes out, or stays. In a study of 3,038 adults aged 65 and over with cataract or glaucoma, followed for 7.8 years on average, cataract removal went with 29% lower risk of dementia from any cause. Evidence: decent
You: a link, not proof. The researchers also looked at glaucoma surgery, another eye operation, as a comparison. It showed no link with dementia. Evidence: decent That makes it less likely the result is just about the kind of people who have operations. It doesn't make it proof. Evidence: decent
The proof
- 3,038 adults aged 65 and over with cataract or glaucoma were followed for 7.8 years on average. Cataract removal went with 29% lower risk of dementia from any cause (hazard ratio 0.71, range 0.62 to 0.83). Evidence: decent
- Glaucoma surgery, used as a negative control, a comparison that shouldn't show the effect, showed no link with dementia (hazard ratio 1.08, range 0.75 to 1.56). Evidence: decent
- Nobody was assigned surgery at random. This is an observational study. Evidence: decent
- Vision loss was added to the Lancet list of changeable dementia risk factors in 2024. Evidence: decent
How to do it
- Book an eye test if your sight has got worse or it's been years since the last one.
- If a cataract turns up, ask your eye doctor whether and when to remove it.
- Decide on surgery for your sight. The dementia link hasn't been tested in a trial. Evidence: decent
Watch out
People who choose surgery may differ from those who don't in ways the study couldn't measure. The glaucoma comparison makes plain bias less likely, not impossible. Evidence: decent No trial has shown that cataract surgery prevents dementia. Evidence: decent