In a review of recent research Australian scientists suggest that omega-3 may reduce the risk of age-related macular degeneration (AMD) by up to a third.

AMD is a progressive and irreversible condition caused by thinning and bleeding around the macula - the central portion of the retina.

It affects in the main those over the age of 60, where the ability to see fine detail is lost and, in severe cases, only some peripheral vision is left.

Preventing AMD is a major public health concern as it affects millions worldwide - one in 50 people over the age of 50, and one in five over the age of 85, have AMD.

Research has already linked omega-3 fatty acids with a variety of health benefits, the most significant being that it may help people with heart disease - this study reviewed the results of nine previous studies on omega-3 and AMD.

The review by researchers at the University of Melbourne involved a total of 88,974 participants, including more than 3,000 with AMD which gives the results greater statistical strength.

The researchers found that eating fish twice a week was linked to a reduced risk of AMD, a 38% reduction in risk in those eating the most omega-3, compared with those eating the least.

Lead author Dr. Elaine Chong, says that omega-3 fatty acids were a vital component of the retina, and it was possible that a shortage of the chemical could "initiate" the disease as retinal cells were constantly shed and renewed.

However, the researchers are cautious about recommending a change in diet, as they say the meta-analysis, while it suggests that consumption of fish and foods rich in omega-3 fatty acids may be linked with a lower risk of AMD, little of the research analysed was set up to provide solid evidence.

Vision charities say given the high cost of treatment for one type of AMD, and the lack of treatment for the other, prevention was a "major public health concern".

They say the meta-analysis confirms that smoking is the only proven avoidable risk factor for AMD and governments need to do more to raise awareness of the link between smoking and blindness.

The study is published in the journal Archives of Ophthalmology.