Contact lens wearers need to be particularly careful when it comes to hygiene and to disinfecting their lenses

Dr Cherry Radford, Moorfields Eye Hospital

The doctors have suggested that infections are being caused by people failing to disinfect their lenses properly or wearing them while swimming or showering.

The study, published in the latest issue of the British Journal of Ophthalmology, examined AK infections in England and Wales between 1997 and 1999.

Tap water risk

It found that most cases involved contact lens wearers in southern England and suggested hard water in the area could be to blame.

Limescale in hard water allows the growth of amoebae and the infection seems to be caused when wearers allow tap water to come into contact with their lenses when storing them or washing and showering.

Soft lenses worn for between a week and a month carried the greatest risk.

Doctors said wearers should be made aware of the condition and take more care to disinfect their lenses.

Dr Cherry Radford from London's Moorfields Eye Hospital said the chances of contracting the infection were still very low.

But she added: "The study shows the contact lens wearers need to be particularly careful when it comes to hygiene and to disinfecting their lenses. They should also avoid tap water. But the risk is still very low."

According to figures from the Royal College of Ophthalmologists, there were 179 cases of AK in England and Wales between October 1997 and October 1999.