A recent meta-analysis explored the association between vision impairment and increased risk for both dementia and cognitive impairment using consolidated data from 22 prospective cohort studies that encompassed more than 6 million participants.

Given the contradictory data that currently exists in the literature, the study, recently published in Ophthalmology, sought to investigate the extent to which vision impairment may be a modifiable risk factor for dementia.

The analysis found that individuals with vision impairment had a 47% increased risk of developing dementia, and a 35% increased risk of cognitive impairment compared to those without vision impairment. The researchers estimated that vision impairment was responsible for 4.7% of the global dementia burden in 2016, affecting approximately 2.1 million people worldwide. The impact of vision impairment on dementia risk was also more pronounced in low- and middle-income countries, where access to eye care and treatment options are often limited.

According to researchers, “vision impairment is a stronger predictor of dementia or cognitive impairment even independent of the effect of hearing impairment,” which has been established as a risk factor for dementia. They described how vision loss may lead to decreased activation of central sensory pathways, which causes “an increased risk of cognitive load and damage to intrinsic brain structures,” and accelerates cognitive decline.

“It is imperative to identify additional modifiable risk factors such as vision impairment because more than four-fifths of [dementia] cases are preventable and treatable,” they noted.

As the global burden of dementia continues to rise, integrating vision care into public health strategies could be a key step in mitigating this challenge, and the investigators encouraged further exploration, especially for research with greater socioeconomic diversity in low- and middle-income countries.