Wearing contact lenses offers clear vision, but this convenience comes with strict rules concerning hygiene and water exposure. It is a fundamental instruction that contact lenses and water should never mix, whether the source is a shower, a swimming pool, or tap water. Ignoring this advice introduces a severe risk of infection to the cornea, sometimes leading to permanent vision impairment. The eye’s surface integrity is compromised when water is introduced while wearing a lens, creating an environment where harmful microorganisms can thrive.
The Danger of Waterborne Pathogens
The primary biological risk involves microorganisms naturally present even in treated tap water. One significant threat is the microscopic organism Acanthamoeba, an amoeba found in various water sources, including plumbing systems. This parasite causes Acanthamoeba Keratitis (AK), a rare but vision-threatening corneal infection. When the amoeba contacts a lens, it adheres to the surface and is held directly against the eye tissue.
The resulting infection is difficult to treat, often requiring months of intensive medication because the amoeba forms protective cysts resistant to disinfectants. AK causes intense eye pain, a sensation that something is lodged in the eye, and light sensitivity. In severe cases, it necessitates a corneal transplant or results in significant vision loss. Other bacteria, such as Pseudomonas aeruginosa, can quickly cause severe microbial keratitis or a corneal ulcer. While water treatment reduces the pathogen count, it does not render the water sterile enough for contact lens wear. The combination of a contact lens and non-sterile water creates an environment for these organisms to multiply rapidly, overcoming the eye’s natural defenses.
Lens Interaction and Trapping Mechanisms
The physical properties of contact lenses, particularly soft lenses, turn a simple splash of water into a health concern, independent of the water’s contaminant level. Soft lenses are porous, designed to absorb moisture and maintain a comfortable fit. When exposed to water, the lens absorbs it like a sponge, pulling in any dissolved minerals, chemicals, or microorganisms. This absorption causes the lens material to swell and change shape, which can distort the fit and cause it to adhere more tightly to the cornea.
Once contaminants are absorbed or trapped, the lens acts as a physical barrier, preventing the cornea’s protective tear film from washing away foreign material. Tears contain antimicrobial agents that normally neutralize threats, but the lens shields the pathogens, allowing them to remain in direct contact with the eye’s surface. Furthermore, a lens that has swollen or changed shape can create microscopic abrasions on the cornea. These tiny scratches provide an easy entry point for trapped bacteria and amoebae to invade the tissue, increasing the risk of a serious infection.
Immediate Symptoms and Chemical Irritation
Exposure to tap or shower water can cause immediate, non-pathogenic irritation due to the chemicals and minerals present. Tap water contains disinfectants like chlorine and various dissolved minerals, which the lens absorbs and then leaches directly onto the eye’s surface. This chemical exposure results in immediate stinging, noticeable redness, and a feeling of grittiness.
The physical interaction of water with the lens material also contributes to acute discomfort. When soft lenses swell from water absorption, they subsequently dehydrate as they lose the non-saline water, leading to increased dryness and reduced oxygen permeability. This temporary structural change can make the lens feel tight and uncomfortable, potentially causing temporary blurred vision or corneal irritation. Adherence after water exposure disrupts the tear film necessary for maintaining a smooth corneal surface, which can trigger an inflammatory response characterized by excessive tearing or a persistent foreign body sensation.
Safe Practices and Accidental Exposure Protocol
The only way to completely avoid the risks associated with water is to remove contact lenses before engaging in any activity that involves water exposure, including showering, swimming, or using a hot tub. For clear vision during these times, consider using daily disposable lenses that can be immediately discarded afterward or wearing prescription eyewear, such as goggles, as a preventative measure.
If water accidentally comes into contact with your lenses, swift action is necessary to minimize the risk of infection. Immediately remove the lenses using clean, completely dry hands. If the lenses are daily disposables, they must be thrown away and not reused under any circumstances.
For reusable lenses, they must be thoroughly cleaned and disinfected by soaking them in a fresh, multipurpose contact lens solution for the full recommended duration, typically overnight. Avoid the temptation to rub or rinse the lenses with water. Ensure the lens case is emptied of any old solution, rinsed with fresh solution, and allowed to air dry. If symptoms such as persistent redness, significant pain, or extreme light sensitivity develop and last for more than an hour after the accidental exposure, consult an eye care professional without delay.