A rare parasitic infection of the eye has seen a threefold increase in the U.K. since 2011. Acanthamoeba is a single-celled, protozoan microorganism found in water such as lakes, oceans, tap water – even swimming pools.

Although the organism is found everywhere, the infection happens 85-plus percent of the time in contact lens wearers.

The organism can get underneath the contact lens and infect the cornea, resulting in acanthamoeba keratitis. Symptoms of this include redness, tearing, severe pain, light sensitivity and blurred vision.

Unfortunately, it can be very difficult to diagnose early on. All of these symptoms are present often with a bacterial infection of the cornea as well. The unique sign of acanthamoeba keratitis is a corneal ring ulcer, but it occurs only in about 50 percent of cases. Once it is diagnosed, it is treated with a concoction of antibiotic drops.

Acanthamoeba can also form cysts that lie dormant and are more difficult to eliminate. If even one cyst remains in the cornea, reinfection can easily occur.

Many cases are sight threatening and result in corneal transplants. I saw one patient years after the fact who had to have a corneal transplant and cataract surgery in her teens due to acanthamoeba complications.

Now that I’ve sufficiently disgusted everyone, how do we prevent this infection? The biggest risk factor is contact lens wear. However, if you are responsible with your contact lenses, this risk decreases exponentially.

Lenses should be kept away from all water sources. If you must have contact lenses around a water source, the safest modality is a daily disposable contact lens. “Daily disposable” means exactly that – the lens is to be thrown away every day, not after two or three days.

Usually a single amoeba gets into a contact lens case and reproduces at high levels within the case. The organisms then attach to the contact lens and infect the eye when the lens is put on the eye.

Lens cases should be cleaned and dried every day. Do not top off solution in your case from the previous day, and change your lenses on time (that means every day, every two weeks, or every month depending on the lens).

If your lens is causing your eye irritation, remove and discard it and your case. Of course, call your eye care provider to evaluate and pain, redness, or blurred vision.

Caroline Bundrick, O.D. is an optometrist practicing at Darling Eye Center, with offices in Bluffton and on Hilton Head Island.