Millions of contact lens users are at risk of contracting a disease caused by a parasite that feeds on bacteria found on contact lenses. It nibbles through the eyeballs causing permanent visual impairment or blindness, scientists have warned.
Many people underestimate the risks of contact lenses, continuing to wear them when their eyes become tired or irritated and not cleaning them as directed.
Such practices increase the risk of permanent damage to the cornea, the transparent outer layer of the eye, including a loss of corneal cells, a thinning of the cornea and a change in the cornea’s shape, referred to as warpage.
“Contact lenses have more of an effect on the cornea than most people realize,” said Dr. Thomas J. Liesegang, an ophthalmologist at the Mayo Clinic in Jacksonville, Florida. He published a review of the literature on the topic in an issue of The CLAO Journal, a publication of the Contact Lens Association of Ophthalmologists. “In some cases, the effects can be reversible and in some they can be permanent.”
An outbreak of Acanthamoeba keratitis (AK), a rare, potentially blinding, corneal infection has been increasing since 2004. Acanthamoeba is a genus of amoebae, one of the most common protozoa in soil, and also frequently found in fresh water and other habitats. The parasite is also found in dust, sea, showers and swimming pools.
The actual number of infections is small but treatment is long, painful and not completely effective.
In the United States, an estimated 85% of cases of this infection occur in contact lens users.
“It is a potential problem for every single contact lens wearer,” the Daily Mail quoted Fiona Henriquez, of the University of the West of Scotland, as saying.
When the lens is put in the eye, it starts to eat its way through the cornea, which is the outer layer of the eyeball and breeding as it goes.
Symptoms include itchy and watery eyes, blurred vision, sensitivity to light, swelling of the upper eyelid and extreme pain.
According to Graeme Stevenson, an optician, vision can be permanently damaged within a week.