Regular vision tests may help predict the risk of developing dementia with research showing a link between deterioration in vision and cognitive decline.

Dementia rates are rapidly increasing in Australia and globally, with vision problems contributing to an estimated 4.7% of the burden.

The research, conducted by Neuroscience Research Australia (NeuRA), highlights the importance of maintaining good vision for overall cognitive health.

“While people are encouraged to get regular eye tests, the research highlights that vision checks are important from a cognitive perspective as well,” said study lead, NeuRA Postdoctoral Research Fellow in Cognitive Health, Dr Nikki-Anne Wilson.

“It is normal for some loss of visual acuity to occur with age, which refers to how clearly objects can be seen from a distance. However, just as we are advised to get our blood pressure checked, we should also be getting our eyes checked too.”

The NeuRA research examined deterioration in vision and cognitive decline over a 12-year period.

The relationship between visual acuity and cognitive performance was evident across multiple cognitive domains, said Dr Wilson. The protein associated with Alzheimer’s disease can be found in both the brain and the retina.

“Neuroimaging findings also indicate that visual impairment results in brain changes both within and beyond parts of the brain which process vision,” she said.

A decline in vision can be caused by a range of factors, some of which are treatable. For example, cataracts, or vision decline that can be supported with the correct glasses.

“What the research is now showing is that identifying these changes early and addressing them may help reduce the risk of developing dementia,” said Dr Wilson.

Uncorrected vision loss was recently included as one of 14 key modifiable dementia risk factors by The Lancet Commission.

It is important to also consider the impact that a decline in vision may have on broader psychosocial factors, say the researchers.

Social connection

Staying socially active could help lessen the negative effects that declining vision has on cognitive health.

“We show for the first time that the relationship between a decline in vision and global cognitive performance may be partly explained by reduced social contact,” Dr Wilson said.

“People experiencing poorer vision may be more likely to avoid social events due to anxiety and this too may impact their cognitive performance. Our findings indicate the importance of maintaining social contact, not only because social isolation is a risk factor for dementia itself but also because it might also help to reduce the impact of other risk factors, such as poorer vision. However, further work is needed.”

Implementing current eye tests

Past studies looking at vision and cognitive health have often relied on self-reported visual impairment, which can be unreliable. One of the strengths of this study is that it used the standard Snellen chart to measure visual acuity.

“This easily available measure can be included as part of an overall clinical approach to supporting brain health in older adults.

“However, we need to ensure equitable access to treatment. We know that there are currently considerable difficulties for many people in accessing appropriate assessment and treatment of eye health. Addressing this will be important as we continue to learn more about the association between vision and dementia risk.”

The research is published in journal Aging and Mental Health here.