Keeping those peepers sharp may go a long way toward keeping seniors’ minds sharp as well—which means regular visits to the eye doctor are in order for those interested in comprehensive dementia prevention.
Vision loss and dementia prevention
While the exact connection between sensory loss and cognitive decline is unknown, early intervention has been shown to stave off the development of dementia in older adults. Roughly 1.8% of all dementia cases in the U.S. are estimated to be caused by preventable vision impairment. That might not sound like a high percentage compared to the 12.4% associated with hypertension or the 9.2% associated with obesity; but considering that percentage represents about 100,000 people who may not otherwise have the disease, the number of lives affected is still significant.
…that percentage represents about 100,000 people who may not otherwise have the disease.
Is there a connection between dementia and vision impairment?
Older people with vision impairment are 1.3 times more likely on average to report confusion or problems with memory, according to a study from 2019. That number goes up to 1.43 for individuals over the age of 70. That’s a big deal considering that roughly 40% of adults that age have suffered some loss of vision—90% of which is treatable. Researcher Joshua R. Ehrlich, MD, MPH, explained to MedPage Today:
“We’ve known for some time that vision impairment is a risk factor for dementia,” he said. “We also know that a very large fraction of vision impairment – possibly in excess of 80% – is avoidable or has simply yet to be addressed.”
As with hearing loss, visual impairment makes the brain work harder at simple tasks, causing unnecessary strain. It can also cause loneliness and isolation for individuals who can no longer keep up with conversations and instructions. So, even though the direct impact of visual impairment is estimated to be relatively small, researchers Jennifer Deal, PhD, and Julio C. Rojas, MD, PhD, contend that the ease with which it can be solved through non-pharmacological means – such as prescription vision correction or cataract surgery – “could have a considerable impact on the prevalence of dementia.”
Correlation between dementia and cataract surgery
A recent study reinforced this claim by demonstrating that those who received cataract surgery had a 30% lower chance of developing dementia than their peers who did not have the surgery. Cataracts – when the eye’s lenses begin to break down and become cloudy – cause blurry vision and can contribute to cognitive and social difficulties.
“Cataract-related visual impairment may decrease neuronal input, potentially accelerating neurodegeneration or magnifying the effect of neurodegeneration through cortical atrophy,” the study’s authors added. “The visual cortex undergoes structural changes with vision loss.”
Vision and dementia in seniors
New research into retinal layer thickness suggests it could be used as a marker to predict dementia in seniors. Researchers concluded that thinner retinal layers were linked to higher rates of cognitive decline.
“Participants with baseline total macular RNFL [retinal nerve fiber layer] thickness below the lowest quartile cutoff value presented a greater decline in cognitive scores and a higher prevalence of cognitive impairment and Alzheimer disease than those with RNFL thickness above the lowest quartile cutoff value,” the researchers wrote.
While there’s no treatment suggested for thinning retinal layers, the real-world application of this research could lead to earlier interventions for those with Alzheimer’s disease.
“Subjective cognitive decline, also described as preclinical AD, is likely to progress over time to mild cognitive impairment and AD,” the report reads. “Therefore, clinicians and researchers have investigated several biomarkers of AD to diagnose the disease as early as possible.”
How often should seniors see an eye doctor?
The importance of regular vision exams for cognitive health is becoming obvious, as this research into vision impairment and its effects on seniors makes clear. While it’s generally recommended that healthy adults visit an eye doctor every two to three years, those over the age of 65 are encouraged to do so each year—specifically because the risk of many eye diseases, including cataracts, glaucoma and macular degeneration, increases exponentially with age. By catching eye diseases when they’re first developing, early interventions (such as cataract extraction and prescription eyeglasses) can be taken to reduce the risk of dementia.
… those over the age of 65 are encouraged to do so each year—specifically because the risk of many eye diseases…increases exponentially with age.
Unfortunately, Medicare does not cover routine eye exams related to glasses or contact lenses. It does, however, cover 80% of cataract surgery or other interventions related to cataract care. Some Medicare supplements will also offer discounts on routine eye exams, so it might be worth looking into additional coverage. Medicaid covers eye exams in many states, though not all of them, and some states will cover vision correction as well.
Forgoing annual eye exams can come with a high price for seniors at risk of dementia—one that’s much bigger than potential out-of-pocket costs. Regular visits to the eye doctor are recommended for sensory, social and cognitive health, and could pay off big time in the prevention of dementia and Alzheimer’s disease.