Using water to clean, rinse, or store contact lenses is a serious risk to eye health and is universally advised against by eye care professionals. The answer to whether water can be used as a substitute for contact lens solution is an unequivocal no. Any type of water—tap, distilled, or bottled—introduces immediate and significant hazards that can lead to severe eye infections and permanent vision damage. Exposing your lenses to water, even for a short time, compromises the lens material and your eye’s natural defenses, making proper disinfection afterward mandatory.
The Specific Risks of Using Water
The primary danger of using water is the presence of microorganisms, even in seemingly clean tap water. Water is a common habitat for a parasitic organism called Acanthamoeba, which can cause a rare but devastating eye infection known as Acanthamoeba keratitis. This organism attaches to the surface of the contact lens and then infects the cornea, leading to intense pain, light sensitivity, and potentially permanent blindness. The infection is notoriously difficult to treat, often requiring weeks or months of intensive medication, and sometimes necessitates a corneal transplant.
Beyond microbial contamination, water poses a physical threat to the lens and the cornea due to osmosis. Contact lens solutions are carefully balanced to be isotonic, meaning they have a salt concentration similar to that of your natural tears. Water, however, is hypotonic, containing a significantly lower concentration of salt. When a soft contact lens is submerged in water, it acts like a sponge, absorbing the water and causing the lens material to swell and change shape.
This swelling distorts the fit of the lens, leading to discomfort and sometimes causing the lens to adhere tightly to the eye. The osmotic imbalance can also affect the corneal surface cells, leading to irritation, blurred vision, and tiny abrasions that create entry points for bacteria. Tap water also contains mineral deposits and impurities, such as calcium and chlorine, which can bind to the lens surface. These deposits cause surface roughness, reducing lens clarity and increasing irritation when the lens is worn.
The Essential Function of Contact Lens Solution
Contact lens solutions are complex, commercially manufactured chemical systems engineered to perform four distinct and necessary functions that water cannot replicate.
Disinfection
The most fundamental function is disinfection, where the solution actively kills or inactivates harmful pathogens, including bacteria, fungi, and viruses, which accumulate on the lens surface during wear. Multipurpose solutions and peroxide systems use specific chemical agents to sterilize the lens, greatly reducing the risk of microbial keratitis.
Cleaning
Cleaning is achieved through the use of surfactants and cleaning agents in the solution formula. These components work to lift and dissolve tear film components like proteins, lipids, and calcium deposits that adhere to the lens material over time. Without this cleaning action, lenses become cloudy, less comfortable, and the buildup provides a hospitable environment for microbial growth.
Lubrication and Hydration
Solutions also provide lubrication and hydration for the lens. Ingredients such as hyaluronic acid or proprietary wetting agents help the lens retain moisture, ensuring it remains soft and pliable for comfortable wear throughout the day. This hydration maintains the lens’s physical integrity and reduces friction against the cornea and eyelids.
pH Balance
Finally, the solution maintains a precise pH balance, mimicking the eye’s natural tear composition through buffering agents and salts. This chemical environment ensures that the lens remains stable and that the solution itself does not irritate the delicate surface of the eye upon insertion. This carefully balanced formula is why commercial solutions are the only safe medium for lens care.
Immediate Safe Actions When Solution is Unavailable
If you find yourself without contact lens solution, the safest and most recommended immediate action is to remove your contact lenses and switch to wearing glasses. For disposable lenses, the best approach is to simply discard them, eliminating the risk of water exposure or contamination. Wearing glasses temporarily is a short-term inconvenience that completely avoids the potential for sight-threatening infection.
If you must save your lenses, you should immediately make an emergency trip to the nearest pharmacy, supermarket, or convenience store to purchase a travel-sized bottle of contact lens solution. Do not attempt to create a homemade saline mixture, use saliva, or use any non-sterile liquids, as these introduce bacteria and are major risk factors for infection. These options are far more dangerous than simply letting the lenses dry out.
If you have no choice but to store them dry overnight, soft lenses will shrivel and become brittle, but they might be salvageable. If they dry out, they must be rehydrated and thoroughly disinfected with fresh, full-strength contact lens solution for the recommended soak time before being worn again. Any lens that has been exposed to water, even briefly, must be properly disinfected before being placed back on the eye.