Vision Loss May Reveal Early Signs of Dementia

The eyes may offer a view into the brain. As an external extension of the central nervous system, they could show early indicators of cognitive decline, according to research.

Two large, recent population studies - one conducted in the United Kingdom and the other in Australia - indicate that people who fare less well in straightforward vision assessments face a greater likelihood of developing dementia more than 10 years later.

The UK research, published in 2024, showed that participants with slower visual processing were more likely to develop dementia during the next 12 years. Meanwhile, the Australian study found that worsening visual acuity was a significant predictor of cognitive decline across a comparable 12-year timeframe.

Vision loss and dementia risk

"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," said the lead author of the Australian study, neuroscientist Nikki-Anne Wilson at Neuroscience Research Australia (NeuRA).

"What the research is now showing is that identifying these changes early and addressing them may help reduce the risk of developing dementia."

Watch the video below for a summary of the research:

In response to persuasive new evidence, The Lancet's most recent 2024 Commission on dementia added vision loss in later life as a risk factor for cognitive decline, estimating that it contributes to as many as 2.2 percent of cases.

For comparison, untreated hearing loss during mid-life is estimated to account for seven percent of cases.

Hearing or vision loss in an older person does not mean that they will inevitably develop dementia. Both problems can point to a range of underlying health conditions, meaning sensory assessments of this kind are imperfect as diagnostic tools for dementia.

At the population level, though, emerging evidence indicates that using hearing aids may lower dementia risk, and treating vision problems could have a similar effect. Evaluating these sensory difficulties in older adults may therefore be important.

Australian study links visual acuity with cognitive decline

The 2024 Australian research examined visual acuity and cognitive decline in 2,281 participants. The scientists' models found that declining eyesight significantly predicted lower scores for problem-solving, memory and attention.

Notably, social engagement appeared to partly mediate this link.

"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," explained Wilson.

"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."

UK visual processing test and dementia diagnoses

In the UK study, more than 8,000 participants completed a vision assessment in which they pressed a button as soon as a triangle appeared on a screen before them.

By the study's conclusion, those with slower visual processing speeds were substantially more likely to have received a dementia diagnosis.

This did not, however, produce a clinically useful prediction for an individual. Put another way, vision scores alone could not determine which participants would later be diagnosed with dementia.

The researchers suggest such assessments could nevertheless be "integrated into the screening process for dementia risk and early diagnoses alongside other cognitive tests."

One recent study linked one in five dementia cases in older people to common vision problems. Treating those visual conditions may potentially lessen some of the factors underlying dementia.

Dementia is extremely complex, and it is unlikely that the condition results from any single risk factor alone.

Evidence is increasingly showing, however, that the eyes are highly sensitive to the general effects of ageing. For example, deterioration visible in retinal scans is a significant predictor of mortality risk; dementia is also the leading cause of death in the UK.

In its latest Commission on dementia, The Lancet recommends ensuring that vision-loss screening and treatment are available to everyone.

"A clear opportunity for dementia prevention exists with treatment of visual loss," the large cohort of experts concludes.

An earlier version of this article was published in November 2025.