A carefree swim while vacationing in Alabama turned into a nightmare for a 23-year-old woman who suffered a devastating loss of vision in her right eye. The culprit was a rare protozoan infection, Acanthamoeba keratitis (AK), contracted while swimming with her contact lenses in place.

US woman suffers vision loss in one eye after swimming with contacts: Rare infection alert. Medbound Times. November 5, 2024.

Initially, her symptoms resembled an ordinary eye infection—redness, pain, and blurry vision. After multiple consultations and even a course of steroid treatment, her condition worsened, leading to complete blindness in the affected eye. It was only after persistent discomfort and visits to several specialists that she was correctly diagnosed with AK. 

Why is it so high risk?

Cases like this are becoming increasingly common. According to an AK epidemiology review, incidence rates nearly doubled between 1999 and 2007 in the US.

Zhang Y, Xu X, Wei Z, et al. The global epidemiology and clinical diagnosis of Acanthamoeba keratitis. J Infect Public Health. 2023;16(6):841–852.

Rupa Wong, MD, a board-certified ophthalmologist, says, “AK used to be quite rare until the advent of soft contact lenses. Even in contact lens wearers, it only occurs in 1 to 2 individuals per million contact lens users.” 

Contact lens wear is a major risk factor, accounting for over 85% of AK cases in developed countries, as noted in the epidemiology review.

Zhang Y, Xu X, Wei Z, et al. The global epidemiology and clinical diagnosis of Acanthamoeba keratitis. J Infect Public Health. 2023;16(6):841–852.

Dr. Wong cautions that Acanthamoeba is found in tap water, soil, and ventilation systems, and wearing contact lenses increases the risk. “Studies have shown how [Acanthamoeba] will immediately adhere to the surface of contacts within 10 seconds. Swimming and showering in contact lenses is a huge risk factor for developing AK, as is cleaning contact lenses with tap water," she says.

Additionally, Acanthamoeba cysts show high resistance to chlorine, increasing the risk when contact lenses are exposed to tap water, well water, or swimming pools.

Petrillo F, Tortori A, Vallino V, et al. Understanding Acanthamoeba keratitis: an in-depth review of a sight-threatening eye infection. Microorganisms. 2024;12(4):758.

Board-certified physician Pamela Tambini, MD, adds that common missteps exacerbating this risk include reusing leftover lens solutions and infrequently cleaning the storage case. Furthermore, sleeping in lenses (if they aren’t extended wear) or wearing them beyond the recommended hours can reduce oxygen supply to the eyes, further raising the risk of an infection.

Such “use, misuse, and abuse” strongly correlates with microbial infections like keratitis, according to Saudi Arabian researchers, which can cause corneal abrasions, ulcers, conjunctivitis, and chronic dry eye.

AlSarhan RS, Abuageelah BM, Alahmadi AA, et al. Use, misuse, and complications of contact lens among the general population of the Kingdom of Saudi Arabia. Cureus. 2023;15(12):e51368.

Severe microbial keratitis and endophthalmitis are known to lead to permanent vision loss.

Recommendations for safer use

Dr. Wong says, “Contacts are an FDA-approved medical device and must be treated as such.” They need to fit the eye’s curvature properly—too tight can block oxygen, too loose causes discomfort. Dr. Wong also stresses strict hygiene: Remove lenses every night, dispose of them on schedule, never reuse daily lenses, limit wear to 10-12 hours per day, and clean them daily with fresh solution. 

For those engaged in water activities, she advises, “Always remove contact lenses before engaging in water activities - whether in a pool, ocean or lake/pond. AK has even been reported in cases of daily contact lens wearers simply showering in their contacts.”

Dr. Tambini recommends glasses as an alternative for certain patients, particularly those prone to eye infections, allergies, dry eyes, or those unable to adhere to proper lens hygiene. Frequent swimmers and others in water-prone environments should also consider glasses over lenses.