Contact lens solution is a multi-purpose liquid designed to clean, disinfect, and safely store lenses between uses. Improper use of this product is a leading factor in contact lens-related eye infections, which can lead to serious complications.
The Daily Rule for Solution in the Case
The most fundamental rule for contact lens care is that the solution in the lens case must be discarded and replaced with fresh solution every time the lenses are stored. Used solution immediately loses disinfecting efficacy upon contact with the lenses. This occurs because the active ingredients are consumed while neutralizing any bacteria or fungi present.
As soon as lenses are placed into the case, the solution becomes contaminated with proteins, lipids, and other debris shed from the tear film. This organic material provides a rich food source for surviving microorganisms, quickly turning the old solution into a breeding ground for pathogens. Reusing this compromised liquid fails to provide the necessary level of disinfection. Always empty the case completely and refill it with new solution, regardless of storage time.
Why Topping Off is Dangerous
The practice of “topping off,” which involves adding new solution to old, used solution, is a major risk factor for infection. While this method may seem like a way to conserve solution, it severely compromises the entire disinfection process. The fresh solution is immediately diluted by the contaminated and neutralized old liquid.
Dilution reduces the concentration of the new solution’s active antimicrobial agents below the level required to effectively kill pathogens. The contaminated mixture then cannot properly sanitize the lenses, allowing pathogens to survive and multiply within the case environment. This creates a high risk for serious infections such as microbial keratitis, which can threaten vision.
Solution Bottle Expiration and Disposal
The ‘use by’ or expiration date printed on the bottle applies to the solution only while the container remains unopened and sealed. Once the bottle is opened, the solution’s sterility is compromised, and the manufacturer’s guarantee of effectiveness changes.
Most manufacturers advise discarding the solution bottle within a specific period after opening, typically between 30 and 90 days, even if the main expiration date is still months away. This rule is in place because the preservatives begin to degrade with exposure to air, making the solution less effective over time. To prevent contamination of the bottle’s contents, never allow the nozzle or tip of the dispenser to touch any surface, including your fingers or the lens case.
Maintaining the Contact Lens Case
After removing the lenses, the old solution must be poured out. The case should then be rubbed and rinsed using a fresh, small amount of contact lens solution. Never use tap water for rinsing the case, as water can harbor dangerous pathogens like Acanthamoeba.
After cleaning, the case must be allowed to air-dry completely. Leave the case open and upside down on a clean paper towel or tissue until the next use. This step helps to minimize the moisture that allows microorganisms to thrive. Additionally, the contact lens case should be replaced every three months to prevent the buildup of biofilm, which can resist disinfection.