19.04.2016

Contact lens wearers warned of amoeba risk

Contact lens wearers warned of amoeba risk

Millions of contact lens wearers in the UK have been warned of a water-borne amoeba that can cause blindness.


Acanthamoeba is abundant in tap water, rivers, ponds, and lakes and can infect anyone who fails to clean their lenses correctly, or keeps them in a dirty case that has not been sterilised.

Despite the abundance of the parasite, few people are aware of its existence and the condition it can cause in lens wearers is often misdiagnosed. Symptoms include itchy and watery eyes, blurred vision, sensitivity to light, swelling of the upper eyelid and extreme pain. The signs are very similar to those of pink eye and can be misdiagnosed if not examined very carefully.

Dr Fiona Henriquez, from the University of the West of Scotland, told the Press Association that the acanthamoeba is a "potential problem for every single contact lens wearer."

Acantamoeba can stick to contact lenses and burrow its way through the cornea, causing acute pain to the wearer. While the incidence of the condition is relatively low in the UK, with doctors treating around 75 people infected with the parasite every year, the potential for millions of people to be affected is present.

"There are no effective medicinal treatments. The drugs used are often ineffective and it's a very brutal regime. It requires hospitalisation and topical applications of a toxic substance to the eye. We are trying to improve the elimination of this parasite and prevent blindness," Dr Henriquez added.


Treatment for the affects of Acantamoeba includes Dettol-like eye drops, with patients initially being treated every 20 minutes, day and night and spending up to three weeks in hospital. The most severe cases are given cornea transplants.

The most common reason for contact lens wearers developing an infection is through poor hygiene regimes, as some people rinse their lenses in tap water. Swimming and taking a shower while wearing lenses is also a potential way of coming into contact with the amoeba.

Experts at the British Science Festival at the University of Aberdeen have encouraged the use of single use daily contact lenses as the safest option to reduce the likelihood of infection.

Graeme Stevenson, an optician working with the scientists to develop better contact lens solutions, said that it could take just a week for the organism to penetrate deep into the cornea, feeding on bacteria as it goes, which could cause scarring that leads to cloudy vision.

The British Contact Lens Association advises against wearing contact lenses while swimming, unless goggles are also worn. And if contact lenses are kept in while showering, eyes should be tightly closed.

Tips for reducing the risk of coming into contact with the amoeba include sterilising contact lens cases, allowing lenses to air-dry face down in a dry environment, rather than a bathroom, and maintaining a strong hygiene regime.


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