Pot bellied Image Credit: Supplied Picture

London: Piling on the fat in middle age could significantly raise a man's risk of blindness later in life.

An expanding waistline puts men in danger of developing age-related macular degeneration (AMD), a leading cause of vision loss, researchers say.

Even small increases in waist size seem to raise the risk of AMD by up to 75 per cent. But women do not appear to be affected, thanks to the presence of female hormone oestrogen.

Abdominal fat releases oestrogen into the body and animal studies suggest the hormone can cause inflammation in blood vessels at the back of the eyes.

Women have higher levels of oestrogen all their lives and so seem less sensitive to its effects, the Daily Mail reports.

Researchers at the University of Melbourne monitored changes in the waistlines of more than 21,000 men and women, aged between 40 and 69, over several years and tracked how many went on to develop AMD.

"Our study underlines the importance of abdominal obesity as a risk factor for AMD," said the scientists, according to a Melbourne statement.

The results showed that even small changes in a man's waist/hip ratio — a measure of his waist compared to his hips — led to a sharp increase in risk.