Water should never be used to store contact lenses, regardless of its source or purity. This includes tap water, bottled water, or even distilled water, as none are sterile environments for lens storage. Contact lenses require a solution to remain hydrated and thoroughly disinfected. Using water introduces significant risks of infection and physical damage, leading to severe eye health complications.
Why Water Poses Serious Risks to Contact Lenses
Storing contact lenses in water introduces two primary dangers: microbial contamination and physical damage to the lens material. All natural water sources, even potable tap water, contain microorganisms harmful to the eye. The most concerning is the single-celled organism Acanthamoeba, which is commonly found in soil and water.
This amoeba can adhere quickly to the lens surface and, if introduced to the eye, can cause a rare but devastating infection called Acanthamoeba keratitis. This infection targets the cornea and can result in extreme pain, permanent vision impairment, or the need for a corneal transplant. Commercial contact lens solutions are formulated with biocides to kill such organisms, a function water cannot replicate.
The second major risk involves the physical integrity of the lens itself. Contact lenses, particularly soft lenses, are engineered to maintain a saline balance to keep their shape and moisture. Water is a hypotonic solution. This difference causes the lens to absorb water, swell, and change its shape through osmosis.
The lens warping that results from water exposure leads to a poor fit against the eye, causing irritation and microscopic abrasions on the cornea. Wearing a damaged or misshapen lens increases discomfort and further compromises the eye’s natural defenses against infection. The distortion can also permanently affect the lens’s intended optical properties, potentially making it unusable.
The Purpose and Types of Contact Lens Solutions
Contact lens solutions are designed to perform multiple functions. Their primary role is disinfection, achieved through active ingredients that kill bacteria, fungi, and other pathogens picked up during wear. These biocides ensure the lenses are safe to place back onto the sensitive surface of the eye.
Solutions also serve a cleaning function by incorporating surfactants and agents that remove protein deposits, lipids, and debris that naturally accumulate on the lens. This prevents buildup that can reduce visual clarity and cause discomfort. The cleaning process is often enhanced by physically rubbing the lenses, even when using “no-rub” multipurpose solutions.
The solution’s composition is carefully balanced to be isotonic, matching the salinity of the natural tear film. This balance prevents the lens from swelling or shrinking, maintaining the correct shape for comfortable and accurate vision. The solution also contains conditioning agents to keep the lens hydrated, which improves comfort.
There are three main types of lens care systems. Multipurpose solutions are the most common, offering cleaning, rinsing, disinfection, and storage in a single product. Hydrogen peroxide systems use a stronger disinfecting agent that requires a neutralization process, often via a special case or tablet, before the lenses can be worn. Saline solution is only for rinsing and hydrating; it contains no disinfecting agents and is unsafe for storage.
Safe Practices for Handling Emergency Storage
If you find yourself without the proper contact lens solution, the safest course of action is to avoid wearing the lenses and switch to eyeglasses. The health of your eyes is more important than temporary convenience, and using any unapproved liquid, including water or saliva, presents a significant health risk. If you must remove your lenses and have no solution, consider them contaminated and discard them if they are disposable.
If discarding the lenses is not an option, the only acceptable last-resort measure is temporary dry storage. The lenses should be placed in a clean, dry contact lens case. This method is only suitable for a short duration, generally less than 12 hours, to prevent the lenses from completely desiccating and becoming brittle.
Once you obtain fresh, approved contact lens solution, the dry lenses must be soaked for the full recommended disinfection cycle. This is an emergency action, not a routine practice, and the lenses should be monitored for any signs of damage or irritation upon reinsertion. Prohibited substitutes, such as homemade saline or eye drops, lack the necessary disinfecting power and should never be used.