The near-universal instruction from eye care professionals is to never wear contact lenses while showering, swimming, or using a hot tub. This warning is rooted in the fact that water, even filtered tap water, is a significant vector for severe eye infections and can physically damage the lens material. Failing to remove lenses before water exposure dramatically increases the risk of trapping contaminants directly against the cornea, the transparent outer layer of the eye.
The Severe Risk of Acanthamoeba Keratitis
The most serious threat posed by water exposure is the potential for contracting Acanthamoeba keratitis, a rare but devastating parasitic infection of the cornea. This infection is caused by Acanthamoeba species, which are microscopic, free-living amoebae commonly found in natural water sources, soil, and even domestic tap water and showerheads. When water containing the parasite contacts a lens worn on the eye, the amoeba can adhere to the lens surface and then become lodged between the lens and the cornea.
A contact lens can create tiny, microscopic abrasions on the cornea, which allows the Acanthamoeba to invade the tissue more easily. The presence of the lens also creates a favorable environment for the parasite, effectively shielding it from the eye’s natural defenses. Once the infection takes hold, it can be extremely difficult to treat because the amoeba can transform into a resilient, dormant cyst form that is highly resistant to many common disinfectants and medications.
Delayed diagnosis is common because the symptoms often mimic less severe conditions. The infection often requires intensive, prolonged treatment with anti-amoebic eye drops. The infection can result in severe, chronic pain, significant vision loss, and in the most severe cases, it can necessitate a corneal transplant or even the removal of the eye.
Why Water is Hazardous to Contact Lens Materials
Beyond the risk of infection, water itself poses a physical and chemical threat to the contact lens and the eye’s surface. Most soft contact lenses are made from hydrophilic, or water-loving, materials like hydrogel or silicone hydrogel. These materials are designed to maintain a specific water content, which dictates their shape, fit, and oxygen permeability on the eye.
When a soft lens is exposed to non-sterile water, such as in a shower, the difference in salinity and pH between the water and the eye’s natural tear film causes the lens to absorb or lose water rapidly. This sudden change can cause the lens to swell, tighten, or change shape, temporarily altering the fit against the cornea. A tight-fitting lens can restrict oxygen flow to the cornea and increase the chance of irritating or scratching the eye’s surface, making it more vulnerable to infection.
Water exposure also washes away the protective layer of the natural tear film, which is the eye’s first line of defense against foreign particles and microbes. The lens material then acts like a sponge, absorbing and concentrating any impurities, chemicals, or microorganisms from the water.
Identifying Symptoms of a Waterborne Eye Infection
Recognizing the signs of a potential waterborne infection is important for prompt treatment and preserving vision. Symptoms of infections like Acanthamoeba keratitis often overlap with more common eye irritations, making early self-diagnosis difficult. A hallmark symptom of Acanthamoeba keratitis is pain that is disproportionately severe compared to the visible signs of redness or injury.
Other symptoms that require immediate attention are:
- Persistent eye pain and redness.
- A sensation of having something stuck in the eye.
- Extreme sensitivity to light (photophobia).
- Blurred or noticeably decreased vision.
- Excessive tearing or watery eyes that do not resolve quickly.
If these symptoms appear after any water exposure while wearing contact lenses, seek an eye care professional immediately, as delayed treatment greatly increases the risk of permanent vision damage.
Actions to Take Following Accidental Exposure
If you accidentally wear your contact lenses while showering, swimming, or using a hot tub, immediate and decisive action is necessary.
- Remove the contact lenses as soon as possible after the exposure.
- The exposed lenses must be discarded immediately, regardless of their replacement schedule.
- Do not attempt to clean or rinse the lenses with tap water or reinsert them.
- Do not try to flush your eyes with tap water; switch to a fresh pair of lenses or glasses temporarily.
After removing the lenses, monitor your eyes closely for any symptoms of infection over the next few days. If you experience any persistent pain, redness, or vision changes, contact your eye doctor immediately for an emergency appointment. Avoid self-treating with over-the-counter eye drops unless specifically advised to do so by a professional, as some medications, like steroids, can worsen a parasitic infection.