Antioxidants can slow loss of sight

Age-related macular degeneration (AMD) is the leading cause of blindness in the elderly. It affects the

macula, the central part of the eye, resulting in increasingly blurred vision. Because the macula is very rich in antioxidants, scientists hypothesised that giving the right nutritional supplements to people at risk might help slow the process.

Usha Chakravarthy, professor of ophthalmology at Queen's University Belfast, gave a supplement containing vitamins C and E, zinc and the carotenoids lutein and zeaxanthin, which are found in leafy vegetables such as spinach, to volunteers. In the trial, which involved 400 people who had AMD in one eye and were at risk of losing their sight in the other, they found the supplement slowed the degeneration and sharpened vision.

"Late AMD causes severe sight loss and has a huge economic impact both in terms of the effects of sight loss itself and in terms of the expensive treatments that are needed to deal with the condition," said Chakravarthy, who is also a consultant ophthalmic surgeon at the Royal hospital in Belfast. "We wanted to carry out the study as prevention of progression to late AMD can result in a reduced financial and societal burden."

The trial was designed after evidence from the US that supplements could help in AMD. A study in 2000 funded by the National Eye Institute in Bethesda found that people at risk of AMD who took nutritional supplements were less likely to lose their sight. The outcome came as a surprise, because vitamins and mineral supplements have been tried in a number of diseases with little success. The US study got good results after five years.

Chakravarthy's trial, at two sites in Northern Ireland and the Irish Republic, was meant to last for three years but ran out of funds. "We had to stop the study and analyse the findings," she said. "At the end of one year, there was no difference between the groups, but in those who had been in the study longer, we found there was a benefit in function."