The answer to whether you can store contact lenses in water for even a single night is unequivocally no. This practice poses significant and immediate risks to eye health, far outweighing the convenience of an overnight fix. Water, including tap, bottled, or distilled varieties, lacks the necessary properties to clean or disinfect contact lenses. Critically, it introduces harmful elements directly to the lens surface, which can lead to severe eye infections, lens damage, and permanent vision impairment.
The Immediate Danger: Why Water Damages Lenses and Eyes
The primary danger of using water for contact lens storage involves the physical integrity of the lens and the introduction of microorganisms. Soft contact lenses are designed to maintain a specific balance of salt and water, known as osmolarity, to match the eye’s natural environment. Water is hypotonic, meaning it lacks the necessary salt and mineral concentrations found in sterile contact lens solutions.
When a lens is immersed in this hypotonic solution, it rapidly absorbs the water, causing it to swell and change its intended shape. This warping can make the lens stick tightly to the cornea, leading to discomfort and micro-abrasions on the eye’s surface. These tiny scratches act as entry points, making the eye highly vulnerable to infection from any pathogens present.
Water is not sterile and contains various microorganisms, including bacteria and fungi, even after treatment. These pathogens, such as Pseudomonas aeruginosa, can easily adhere to the lens material when stored in water. Contact lens solutions are specifically formulated to clean and actively disinfect the lens, a function water cannot replicate. This leaves the lens surface contaminated and unsafe to place back onto the eye.
The Primary Infection Risk: Understanding Acanthamoeba Keratitis
The most severe risk associated with water exposure is infection by the parasite Acanthamoeba, leading to Acanthamoeba keratitis (AK). This microscopic, single-celled organism is commonly found in the environment, including household tap water. The organism exists in two forms: the active trophozoite and the resilient cyst, which is difficult to eradicate.
When a contact lens is stored in water, the Acanthamoeba can attach to the lens surface and transfer directly to the cornea. If the eye has minor damage, which can be caused by the water-warped lens, the amoeba can invade the corneal tissue. Symptoms of AK include severe eye pain, blurred vision, intense light sensitivity, and excessive tearing.
Acanthamoeba keratitis is difficult to treat, often requiring months of intensive topical medication, and the infection may not fully resolve. In advanced cases, the damage caused by the parasite can lead to permanent vision loss or necessitate a corneal transplant. The majority of AK cases, approximately 85%, occur in contact lens wearers, emphasizing the direct link between improper lens care and water exposure.
Safe Emergency Storage Options
If you find yourself without contact lens solution and must remove your lenses, the safest course of action is to discard them immediately. This prevents contamination and the potential for eye infection or corneal damage. If discarding the lenses is not an option, the priority must be to obtain a sterile, commercially manufactured disinfecting solution as soon as possible.
In a short-term emergency where no proper solution is available, sterile saline solution is a marginally safer alternative to water, but it is not recommended. Saline solution will keep the lens hydrated and maintain its shape, but it contains no disinfecting agents to kill pathogens. After using saline, the lenses must be thoroughly cleaned and disinfected with a proper multipurpose solution before they are worn again.
If you must store the lenses without solution until you can purchase one, they should be removed and kept dry in a clean, airtight container. They must be discarded if more than 12 hours pass. Never attempt to create a homemade solution. Always prioritize purchasing a small, travel-sized bottle of disinfecting solution from a nearby store, as this is the only safe option for overnight storage.