Age-related macular degeneration (AMD) leading to vision loss is linked with increasing girth in men, report researchers at the University of Melbourne.

The researchers tracked changes in the waistlines of more than 21,000 men and women, aged between 40 and 69, over several years and observed how many developed AMD later on. They found that abdominal fat releases the female hormone oestrogen into the body. Using animals in their studies they discovered that the hormone can cause inflammation in blood vessels at the back of the eyes. This is why women, having had higher levels of oestrogen throughout their lives, are not similarly affected.

'There is evidence that chronic inflammation is involved in AMD and obesity is a pro-inflammatory state,' said the scientists.

Small changes in a man's waist/hip ratio lead to a sharp increase in risk. A healthy score is usually anything below a ratio of around 0.95. But if it rises above that, the risk of diabetes and heart disease looms up. With each increase of 0.1 in the waist/hip ratio, a man's chances of developing AMD goes up by 75 per cent.

Most develop 'dry AMD', which develops over several years. 'Wet AMD', which can cause blindness in just three months, happens when new blood vessels develop over the macula in the eye and then start to leak fluid, causing scar tissue to form and destroying vision in the centre of the eye. This makes it difficult to recognize faces, read or watch TV.