The results suggest that vision fixes, like a new eyeglass prescription or surgery to remove cataracts, can go a long way toward helping older people stay mentally sharp, said lead author D. Diane Zheng of the University of Miami Miller School of Medicine.
“Taking care of your vision is important in order to maintain good cognitive function,” she said in a telephone interview.
Poor eyesight and weakening mental function are common in older people and related to one another, but the question of whether vision influences cognition, or vice versa, has not been clear, the study team writes in JAMA Ophthalmology.
To investigate, Zheng’s team followed 2,520 adults for eight years, testing their vision and cognitive status every other year.
Over the course of the study, average visual decline was roughly equivalent to losing the ability to read one line of an eye chart. People who had worse vision at the beginning of the study had worse scores on the cognitive exam as well. A person’s vision at their previous check-up was related to their mental function at the following check-up. While mental function at one check-up was also related to vision at the following exam, the effect of vision on subsequent mental function was significantly stronger.
While the mechanism behind the vision-cognition relationship isn’t well understood, Zheng said, worsening vision can discourage people from brain-stimulating activities like doing crosswords and engaging with other people.
She recommended that older adults get regular eye checkups, and have any vision symptoms checked out and treated promptly.
“This study provides additional evidence that would suggest that people who can keep their vision healthy as they age might also be protecting their cognitive health,” said Dr. Heather E. Whitson of Duke University School of Medicine and Durham VA Medical Center, who wasn’t involved in the research.
“If you’re aging without good vision, not only are you giving your brain less stimulation, you might be altering your brain at a structural level,” she said in a phone interview.
The good news, Whitson added, is that poor vision is one of the few risk factors for cognitive decline that is potentially modifiable. Even incurable causes of age-related vision loss such as glaucoma and age-related macular degeneration “are highly treatable, so we can reduce the amount of vision loss that people suffer from if they’re detected early.”