Contact lens solution is a specially formulated, sterile liquid designed to keep contact lenses clean, disinfected, and hydrated. It is a complex, balanced product that protects the delicate surface of the eye. Maintaining a sterile environment is essential for eye health, and any deviation from commercial solutions introduces significant risk. Homemade solutions offer only a brief, temporary rinse and must never be used for disinfection or long-term storage. Using non-sterile liquids can lead to severe eye infections, including a rare condition that may cause blindness.
The Critical Difference: Rinsing vs. Disinfecting
The primary function of a commercial contact solution is disinfection, which is fundamentally different from a simple rinse. Disinfection involves actively killing harmful microorganisms, such as bacteria, fungi, and protozoa, that accumulate on the lens surface during wear. This process uses potent chemical agents not found in basic saline.
Rinsing is a mechanical action that removes loose debris and rehydrates the lens material. A simple saline solution matches the natural salt concentration of tears, making it comfortable for the eye. However, saline lacks antimicrobial capability, meaning it cannot sterilize the lens or prevent pathogen growth.
Storing lenses in a non-disinfecting solution allows residual microorganisms to multiply rapidly, turning the lens case into a dangerous breeding ground. Even if a homemade mixture appears clean, it lacks the sustained germ-killing power necessary for safe lens storage. True disinfection requires a sophisticated chemical balance impossible to replicate safely outside of a regulated laboratory environment.
Safely Creating a Temporary Saline Rinse
If a true emergency requires a temporary rinse, a homemade saline solution can be prepared but only for immediate use. This rinse is strictly for moistening a lens briefly before insertion, and it should never be used to store lenses. To create an isotonic solution matching the 0.9% salt concentration of human tears, a specific ratio must be followed.
The process begins by boiling one cup of water for at least 15 minutes to achieve temporary sterilization. After allowing the water to cool completely, stir in exactly one-half teaspoon of non-iodized table salt until it fully dissolves. Non-iodized salt is preferred because iodine and other additives can cause eye irritation.
The water source should ideally be distilled, but if tap water is used, extended boiling is necessary to kill bacteria and pathogens. Despite these precautions, the resulting mixture is not truly sterile and must be used immediately, with any remainder discarded. Even a properly prepared emergency rinse carries a contamination risk because the preparation environment and containers are not medically sterile.
Why Commercial Solutions Are Non-Negotiable
Commercial contact lens solutions are complex medical devices subject to rigorous oversight by regulatory bodies like the FDA. They are formulated with multiple sophisticated components, each with a specific function far beyond simple hydration. These products contain buffer systems, such as borate or phosphate, which maintain a precise pH balance to prevent irritation when the solution touches the eye.
Commercial solutions utilize surfactants, which are cleaning agents that break down the natural protein and lipid deposits that build up on the lens surface. These surfactants help wash away debris that can cloud vision and harbor microbes. This cleaning action is paired with powerful, tested antimicrobial agents like polyhexamethylene biguanide (PHMB) or polyquaternium-1.
These disinfectants are engineered to kill a broad spectrum of microbes while remaining gentle enough for the eye’s delicate tissues. Hydrogen peroxide-based solutions offer an alternative, providing deep cleaning and disinfection, though they require a neutralizing step before the lenses can be worn. This chemical complexity and proven efficacy underscore why commercial solutions are the only safe option for long-term lens care and storage.
What to Do If You Run Out
When a commercial solution is unavailable, the safest course of action is to immediately remove and discard the contact lenses. Forcing the use of any unapproved substitute significantly increases the risk of severe eye infection. If discarding the lenses is not an option, the absolute last resort is to store them dry in a clean case until a proper solution can be purchased.
Never use tap water, bottled water, or saliva as a substitute for contact solution. Tap water and bottled water, even boiled, can contain the Acanthamoeba organism, which causes a painful and sight-threatening infection known as Acanthamoeba keratitis. Saliva is full of bacteria and is an extremely dangerous substitute.
If the lenses must be rinsed before insertion and no commercial sterile saline is available, using a sealed, single-use packet of sterile saline intended for medical rinsing is the only safe temporary measure. This is only a rinse and does not disinfect, so the lenses must be cleaned and disinfected with a proper solution at the earliest opportunity. Obtaining a fresh bottle of commercial contact lens solution as quickly as possible remains the highest priority.