Eye problems significantly raise the risk of dementia.
Experts say that patients with deteriorating vision are 60 per cent more likely to end up with an impaired ability to remember, think or make decisions.
The researchers analysed data on over 12,000 adults and found that the risk of dementia was 61 per cent higher for sufferers of diabetes-related eye disease. The team from the Guangdong Academy of Medical Sciences in China said that they could not establish a reason for the correlation.
It has been suggested that eye conditions are associated with well-known risk factors for dementia such as heart disease.
The experts said: "Age-related macular degeneration, cataract and diabetes-related eye disease - but not glaucoma - are associated with an increased risk of dementia.
"Individuals with both ophthalmic and systemic conditions are at higher risk of dementia compared with those with an ophthalmic or systemic condition only."