Falls in older people could be prevented if they stop wearing varifocal glasses while outside , new research indicates.

The study claims 40% of falls in the elderly could be prevented if single lens glasses were worn outside.

Varifocal lenses are widely prescribed as they correct near and far-sightedness in one pair of glasses and are therefore more convenient to wear.

But the research from Australia suggests they can affect people's balance, leading to falls.

Researchers from Sydney studied more than 600 people aged either over 80 or over 65 with a history of falls. All of them used varifocals and wore them outside at least three times a week.

Half were given single lens glasses for going out, the other half were not.  For those who regularly went outside, there were 40% fewer incidents with the single lens wearers.

The authors recommend that older people who are active outside should be advised to switch between single and varifocal glasses.

The research is published in the British Medical Journal.