Lens solution the culprit in worldwide contact lens scareJun 9, 2006 | www.channelnewsasia.com ReNu lens cleaning solution itself.
The findings were released at the first day of the Asia-Pacific Academy of Ophthalmology Congress.
Most contact lens cleaning solutions contain just one polymer, but ReNu MoistureLoc multipurpose contact lens solution has three.
Its manufacturer, Bausch and Lomb, thought this would keep the eyes of contact lens users moist and comfortable, but the formula ended up trapping fungus instead of killing it.
Said Associate Professor Donald Tan, senior consultant ophthalmologist and director of the Singapore Eye Research Institute, "The disinfectant in MoistureLoc is actually very effective. The problem is when you add other things in, like the polymers, to improve comfort. The polymers are actually trapping the fungus so that the disinfectant, which is very strong, cannot get at the fungus. So it is a formulation problem."
And the fungus grows by the day with each repeated use.
Professor Tan said, "Bausch and Lomb has found that in open bottles you can get the fungus growing on the tip and on the cap of the open bottle because of the trapping of the fungus there. And what appears to be happening is that every time you add the solution onto your contact lens case, you actually add in fungus."
But doctors say users themselves must also practice good contact lens cleaning and care regimens.
Some 300 cases of fungal corneal infection have been reported across the US, Malaysia and Singapore.
In Singapore, 90 percent of the 80 patients had used the solutions from the ReNu range; three quarters of them were using ReNu MoistureLoc solution.
The Singapore Eye Research Institute has set up a special task force to study the hygiene habits of some 100 contact lens users, to look into preventing such fungal infections from recurring.
The study would include both healthy contact lens users and those who had the fungal corneal infection.
The institute is also working with microbiologists on a case control study.