All forms of visual impairment among individuals aged 71 years and older are associated with a higher prevalence of dementia, according to new research findings reported in JAMA Ophthalmology.
Although previous studies have highlighted the link between visual impairment and dementia, “most of the VI (visual impairment) in older adults is preventable or has simply not yet been addressed with interventions like eyeglasses or cataract surgery,” wrote lead study author Olivia J. Killeen, M.D., M.S., of the department of ophthalmology and visual sciences at the University of Michigan, Ann Arbor, and colleagues.
“Cataract surgery reduces the risk of dementia and optimizing vision may prevent up to 100,000 prevalent cases of dementia in the US,” they added.
Census data show that by 2030, all baby boomers — or those born in the post World War II years 1946 to 1964 — will be at least 65 years old. As the elderly population grows in the coming years, so will the number of individuals with age-related visual impairtment and associated dementia.
What’s more, published research on the link between visual impairment and dementia is either outdated or relies on self-reported survey data, which could underestimate the prevalence.
Killeen and her colleagues used data from the 2021 National Health and Aging Trends Study (NHATS) to conduct study. To better determine nationally representative estimates of the association, they assessed data from 2,967 NHATS participants recorded in 2021. They chose 2021 because that is when the NHATS incorporated “tablet-based tests of distance and near visual acuity and contrast sensitivity (CS) with habitual correction” to objectively measure visual impairment.
All participants were Medicare beneficiaries, while just over half were female (55.3%) and median participant age was 76.9 years.
Of the patients included, 12.3% had dementia. However, data showed prevalence rose to 21.5% among those with near visual impairment. For patients with mild distance visual impairment, dementia prevalence was measured at 19.1% but increased to 32% for those with moderate or severe distance visual impairment or who were blind.
Among those with CS impairment, dementia prevalence was measured at 25.9%.
In addition, after adjusting for covariates like age, smoking status, and education, Killeen and colleagues found “dementia prevalence was higher among participants with near VI and CS impairment than those without and among participants with moderate to severe distance VI or blindness.”
Several interventions exist to address visual impairment in this population. For those with near visual impairment, over-the-counter reading glasses can be an effective way to deal with the condition. Because a high percentage of distance visual impairment results from uncorrected refractive error or cataracts, glasses and cataract surgery can be used to improve vision in this population.
According to Killeen and colleagues, the current study is the first since 2008 to use objectively measured and nationally representative population data to investigate the link between visual impairment and dementia among seniors.
However, its cross-sectional design and inclusion of individuals aged 71 and up mark limitations. Researchers were also unable to assess the root causes of patients’ visual impairment.
Overall, “prioritizing vision health may be key to optimizing both sight and overall health and well-being,” Killeen and colleagues concluded.
“Randomized trials are warranted to determine whether optimizing vision is a viable strategy to slow cognitive decline and reduce dementia risk.”