Maintaining healthy vision may slow down cognitive decline in older people, a new study suggests.

Researchers say that vision fixes, including a new eyeglass prescription or surgery to remove cataracts, can go a long way toward helping seniors stay mentally sharp.

Past studies have suggested that eating a healthy diet, exercising regularly and getting enough sleep are all ways to reduce risk of cognitive decline.

With the number of adults with dementia expected to triple by 2050, the scientists from the University of Miami Miller School of Medicine hope that retaining healthy eyesight could be a new intervention to prevent, or delay, the onset of age-related diseases.

For the study, the researchers followed 2,520 adults, between the ages of 65 and 84 for eight years, testing their vision and cognitive status every other year.

With each vision test, the participants on average lost the ability read one line of an eye chart.

Results showed that the adults who had worse vision at the start of the study also had worse scores on the cognitive exam.

The worse there was a decline in visual acuity, or the sharpness of vision, there was an equal decline seen in cognitive function.

Cognitive decline increased from 11 per cent at the start of the study to almost 21 per cent at the end.  

The team found that vision had a stronger influence on cognition than the reverse. 

The researchers admit they don’t exactly understand the mechanism behind the relationship between vision and cognition.

However, according to lead author Diane Zheng, a PhD student in the department of epidemiology at the University Of Miami Miller School Of Medicine, worsening vision can discourage people from brain-stimulating activities like doing crosswords and engaging with other people.

"Taking care of your vision is important in order to maintain good cognitive function,” she said.

According to an essay published in JAMA Ophthalmology last month, both cognitive decline and vision loss are expected to increase significantly in line with population growth.

The number of people with dementia is estimated to triple from 50 million to 132 million in 2050 and the number of those with blindness will rise from 38 million to 115 million in 2050.

Zheng said she recommends that older adults get regular eye check-ups, and have any vision symptoms checked out and treated promptly.

Dr Heather Whitson of Duke University School of Medicine and Durham VA Medical Centre, who wasn’t involved in the research, told Reuters that causes of age-related vision loss, such as glaucoma, ‘are highly treatable’ and the amount of eyesight loss can be reduced when detected early.

However, she said that the research provides an added benefit of maintaining healthy eyesight. 

"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.

Agencies