Scientists believe that the number of cases of dementia could be reduced by correcting vision problems with surgery, glasses or contact lenses.
The disorder destroys the lives of millions of people worldwide, slowly robbing them of their memories and independence.
However, according to the NHS, around 40 percent of dementia cases are preventable.
Previous research has shown that preventing hearing loss, treating depression and getting enough exercise are all ways to reduce the risk.
Scientists at the US Johns Hopkins University now claim that solving vision problems could also prevent a fifth of cases.
According to the NHS, 40 percent of dementia cases could be prevented.
Researchers used data collected annually during a survey of U.S. adults aged 65 and older, which included 2,767 participants who were eligible for visual and cognitive testing.
The researchers used the strength of the association between visual impairment and dementia to calculate the percentage of dementia cases that could be attributed to three types of visual impairment.
Based on the data, they estimate that 19 percent of dementia diagnoses in people over 71 were due to at least one visual impairment: nearsightedness, farsightedness, or the ability to see small objects sharply and clearly.
Because vision loss can also be caused by diabetes, the researchers took this into account in the analysis.
Fifteen percent of dementia cases attributed to vision loss involved difficulty seeing very small objects, known medically as contrast sensitivity.
Researchers used data collected annually from a survey of U.S. adults aged 65 and older, and included 2,767 participants who were eligible for a visual and cognitive test
Contrast sensitivity disorders occur in several eye diseases, but most commonly in cataracts. These are cloudy spots that form on the lens, a small, transparent disk in your eye.
According to the study authors, this can be remedied through cataract surgery, which reduces the risk of dementia in the elderly by almost three percent.
In other cases, ‘best corrected vision’ must be provided in the form of glasses or lenses to ‘affect visual performance’.
The findings come after hearing loss was named top of the list of 12 modifiable risk factors for the global burden of dementia in the 2020 Lancet Dementia Commission report.
According to the Alzheimer’s Society, not being able to understand sounds and speech can cause the brain to work harder.
The charity explains that this extra effort can lead to changes in the brain that affect our memory and thinking,
Visual impairment was not among the most important modifiable factors of dementia in the Lancet report.
However, experts say that, like hearing, sight is a “sensory stimulus” and without sight we are less likely to engage in activities that protect us from dementia, including socializing.
Professor Eef Hogervorst from Loughborough University, who was not involved in the research, told The Guardian that vision loss can lead not only to reduced activity but also to dementia. This is because people who use their eyes less can get less blood to the brain.
Professor Gill Livingston, a dementia doctor at University College London, said brain stimulation is essential to keep your brain fit.
“Things that make it harder to stimulate your brain, like loss of vision and hearing, mean you get less cognitive stimulation,” she said. The I.
There are currently an estimated 982,000 people with dementia in the UK, with this number expected to rise to 1.4 million by 2040.
An estimated 6.7 million Americans aged 65 and older currently have Alzheimer’s disease.
This number could grow to 13.8 million by 2060.
Alzheimer’s disease is the most common form of dementia, affecting 50 to 75 percent of people diagnosed with it.