People who take aspirin just once a week are more than twice as likely to develop age-related blindness, a new Australian study has found.

A team from Sydney's Westmead Millennium Institute for medical research conducted a 15-year study that found that regular users of the drug are significantly more likely to suffer from macular degeneration, the leading cause of blindness in older people.

The researchers, led by Professor Paul Mitchell, studied 2000 people over the age of 50 living in the Blue Mountains.

Participants had their eyes tested, and were asked about the medication they were taking, and how often they were taking it.

Nearly 10 per cent of those taking aspirin at least once a week developed the condition, compared to 3.7 per cent of non-aspirin users.

"People who are using aspirin on a regular basis, at least once a week, but most were actually taking it daily, had about a two-and-a-half-times increased likelihood of developing macular degeneration over time," Mitchell said.

The results are consistent with US and European studies released last year.

But despite the findings, Mitchell says people shouldn't stop taking their aspirin without consulting their doctor.

He says more research would need to be done before clinical use of the drug was revised.

Aspirin is used to reduce the risk of strokes and some heart conditions.

The study is published in the current issue of JAMA Internal Medicine.