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Contact lens wearers at risk from blinding infection

November 03, 2003

Some 2.2 million people wear contact lenses in England, with 900,000 alone in the southeast. Given the growing popularity in fashion contact lenses for night-clubbers, and for people who want a temporary change of eye colour, there needs to be greater awareness about the risks involved when people fail to clean their lenses properly.

Dr Naveed Khan, a researcher at Birkbeck, University of London, is investigating a parasite that can cause a blinding infection in contact lens wearers. He outlined the dangers, saying: "The Acanthamoeba parasite has developed specialised spine-like structures on its surface that hold on tightly to the cornea so that it isn't washed away. Then it invades the eye, causing severe damage to the tissue with excruciating pain."

"If people use tap water to clean their lenses instead of solution, they risk being infected by the Acanthamoeba parasite. This causes a particularly resistant eye infection that eats the cornea and results in blindness. The parasite is present everywhere. As well as tap water, it is found on table tops - if I cleaned my work bench I would find it."

Approximately 10-15 people out of 100,000 contact lens wearers are reported as infected by the parasite in the UK every year, but Dr Khan believes the actual number of cases could be much higher. "Misdiagnosis of Acanthamoeba is common practice in the UK and worldwide," he says. "This is due to a lack of expertise in identifying this relatively new organism."

He continues: "In some cases, people in the UK have lost an eye because of this infection and even then this organism is not diagnosed. Quite frequently, we only hear about these cases in the lab when it is too late. There has to be continued awareness about these emerging pathogens, which are causing serious infections and affecting human health and increasing burdens on our economy."

Dr Khan's research involves growing the outside layer of the cornea from a human eye in culture to determine "how the parasite produces so much damage that it results in blindness." His team is also using a complete cornea model, in collaboration with the University of East Anglia, to investigate infection in the context of the whole eye."

"There are only a couple of drugs available for this infection. More worryingly, Acanthamoeba is becoming resistant, so there is no effective treatment, it is simply a matter of trial and error. It's very obvious that we have to find another approach."

Dr Khan and his team are investigating how parasites, like Acanthamoeba, and other infectious diseases, such as malaria, cross over from the bloodstream to the central nervous system, breaking through the blood-brain barrier, which usually prevents the entry of micro-organisms and molecules. Using a unique model of the blood-brain barrier, developed by isolating human brain tissue, Dr Khan hopes to be better able to determine drug effectiveness. His research is funded by grants from the British Council for Prevention of Blindness, the Royal Society and the Nuffield Foundation.

He will meet the Chancellor of the University of London, The Princess Royal, when she tours Birkbeck on Wednesday 5 November to view the completion of the College's £18.5m campus consolidation project. The new and improved facilities at Birkbeck - now in its 180th year - will allow the College to further strengthen its facilities for achieving research excellence while also providing high-quality teaching for part-time students.

Professor David Latchman, Master of Birkbeck, says: "The completion of the Malet Street Project further strengthens Birkbeck as an institution that combines a unique model of international-quality research activity with high-quality part-time teaching. In an environment where the Government has chosen the 18-30 age group as a target to increase participation in adult education, Birkbeck continues to enhance the provision of lifelong learning for all individuals who can benefit from it."

Birkbeck College