The eating disorder, anorexia nervosa, may cause potentially serious damage to the eyes, the results of a new study indicate.

Anorexia nervosa is characterised by an obsessive desire to lose weight and dissatisfaction with body weight and shape. Extreme weight loss is achieved by excessive dieting behaviours, including the use of laxatives and self-induced vomiting.

According to Greek researchers, in developed countries, the disorder affects up to 3% of affluent women. While it also increasingly affects men, around 10 women will be affected for every one man.

Furthermore, it is the third most common chronic disease among teenage girls and up to one in 10 of these will die from it.

The researchers analysed the thickness of the macula and its electrical activity in both eyes of 13 women with anorexia nervosa and in 20 healthy women of the same age. The macula is found near the centre of the retina at the back of the eye and is responsible for fine detailed central vision and the processing of light.

The average age of the participants was 28 and those with anorexia had the condition for an average of 10 years.

The researchers found that tests to determine how well the eyes picked up fine detail, central vision and colour showed that there were no obvious visual problems and that the eyes were working normally in both sets of women.

However, a further analysis showed that the macula and the nerve layers feeding it were significantly thinner in the eyes of the women with anorexia nervosa.

There was also significantly less electrical activity in the eyes of the women with the disorder. This is a key element of the brain's ability to process visual images.

The study noted that there appeared to be differences between women with different patterns of anorexia. For example, the fovea - a small pit at the centre of the macula that is rich in light sensitive cone cells - was thinner in women who binged and purged than in those who simply severely restricted their calorie intake.

The researchers from the University of Athens concluded that it is not yet clear whether macular thinning and decreased electrical activity are the initial stages of progressive blindness or whether these signs will revert back to normal if normal eating patterns are resumed.

Details of these findings are published in the British Journal of Ophthalmology.

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