Eye care professionals universally advise against exposing contact lenses to water, including while showering. This directive is a serious health warning rooted in the potential for severe, vision-threatening eye infections. The risk comes not from the water itself, but from microscopic organisms that thrive within non-sterile water sources. Understanding this biological threat explains why this seemingly minor act carries significant consequences for eye health.
The Primary Risk: Waterborne Microbes
The danger associated with showering in contact lenses stems from the fact that domestic water is not sterile, even when it is safe for drinking. Tap water, well water, and filtered shower water contain a variety of microorganisms, including bacteria, fungi, and protozoa. While the body’s digestive system can neutralize these microbes if swallowed, the delicate surface of the eye lacks this defense mechanism.
One of the most concerning contaminants is a microscopic amoeba known as Acanthamoeba, which is commonly found in municipal water supplies. This protozoan is harmless in many contexts but becomes an opportunistic pathogen when introduced directly to the eye. The presence of non-sterile water, like the spray from a showerhead, introduces these infectious agents to the contact lens surface.
Acanthamoeba Keratitis: The Severe Outcome
Exposure to waterborne pathogens, particularly Acanthamoeba, places contact lens wearers at risk for a devastating infection called Acanthamoeba keratitis (AK). This condition involves the amoeba invading and inflaming the cornea, the clear, dome-shaped outer layer of the eye. Diagnosis is often difficult because early symptoms, such as redness, light sensitivity, and a feeling that something is stuck in the eye, can mimic more common infections.
The hallmark of AK is severe pain, which is disproportionate to the initial physical findings, due to the amoeba attacking the corneal nerves. If the infection is not treated promptly, the amoeba can burrow deeper into the corneal tissue. This progression can lead to permanent corneal scarring, significant vision loss, and often necessitates a corneal transplant to restore sight. Treatment for AK can be lengthy, sometimes requiring months of specialized antimicrobial eye drops.
How Lenses Create a Trap
Contact lenses significantly elevate the risk of infection because they change the interaction between the eye and the waterborne microbes. Soft contact lenses are porous, meaning they readily absorb water, similar to a sponge. When water hits the lens, it soaks up, trapping microbes, like Acanthamoeba, directly against the surface of the cornea.
The water absorption can also cause the lens to change shape or swell, which may lead to discomfort. This altered fit can sometimes cause tiny abrasions on the cornea as the lens moves. These micro-abrasions provide an easy entry point for the trapped microorganisms to penetrate the eye’s protective outer layer, initiating the infectious process.
Water Safety for Contact Lens Users
The precaution against water exposure extends beyond the shower to nearly all water activities when wearing lenses. It is recommended to remove lenses before swimming in pools, hot tubs, lakes, or oceans, as these environments also harbor various microorganisms. Furthermore, never use tap water to rinse or store contact lenses or their storage case.
Proper Lens Care After Water Exposure
Only sterile contact lens solutions, specifically formulated for cleaning and disinfecting, should be used for lens care. If lenses are accidentally exposed to water, they should be removed immediately. For reusable lenses, a thorough disinfection cycle should be completed before reinsertion, and daily disposable lenses should simply be discarded to prevent contamination.