Contact lenses are medical devices with specific time limits governing their safe use. Understanding these limits is essential for protecting eye health, as there is a significant difference between the factory-set expiration date and the wear-and-disposal date. Ignoring either time frame can compromise the lens’s sterility or the health of your cornea. The factory date relates to the lens’s shelf life inside its unopened packaging, while the wear date dictates how long you can safely use the lens after opening.
Locating and Interpreting Contact Lens Packaging Dates
The factory expiration date, which represents the lens’s shelf life, is printed on both the outer carton and the individual foil blister packs. Manufacturers use a standardized symbol, often an hourglass icon or the abbreviation “EXP,” followed by a date usually displayed in Month/Year format. This date is the manufacturer’s guarantee that the lens and the sterile saline solution remain uncontaminated and safe for use.
The date is set because the integrity of the blister pack’s seal is not guaranteed indefinitely. Over time, microscopic failures can develop, potentially allowing oxygen or microbes to enter the sterile environment. Once this expiration date passes, the manufacturer can no longer vouch for the lens’s sterility, making the lens a potential risk for contamination.
Adhering to the Contact Lens Replacement Schedule
Once the foil seal is peeled back, the factory expiration date becomes irrelevant, and the lens replacement schedule begins. This schedule is the maximum time a lens material is designed to be worn before it must be discarded, regardless of usage frequency. The schedule is determined by the lens type, which includes daily, bi-weekly, or monthly replacement options.
Daily disposable lenses are designed for a single use and must be thrown away after one day, as they are not intended for cleaning or re-wearing. Bi-weekly lenses are typically worn for a maximum of 14 days, while monthly lenses are used for up to 30 days; both require daily cleaning and disinfection. The clock starts ticking the moment the sterile package is opened, meaning a monthly lens must be discarded after 30 days, even if worn infrequently.
Strict adherence to the wear schedule is necessary because the lens material immediately begins to accumulate deposits from your tears, such as proteins and lipids. Stretching the wear time allows these deposits to build up excessively, which reduces the lens’s comfort and clarity. A practical way to manage this schedule is by setting a reminder or marking a calendar with the disposal date when you open a new pair.
The Risks of Wearing Expired Contact Lenses
Wearing an expired, unopened contact lens carries the immediate risk of a severe eye infection. If the sterile seal has been compromised, the lens is no longer suspended in a germ-free solution, introducing harmful bacteria or fungi upon insertion. This contamination can lead to immediate irritation or, in serious cases, microbial keratitis, which is an infection of the cornea.
For lenses worn past their replacement schedule, the risk shifts to material degradation and deposit accumulation. The buildup of proteins and lipids reduces the amount of oxygen reaching the cornea, a condition known as corneal hypoxia. Over time, this oxygen deprivation can lead to swelling and compromise the cornea’s health, increasing susceptibility to infection.
Continued overwearing also leads to lens material breakdown, which can cause the lens to become warped or brittle, potentially scratching the cornea. Symptoms like persistent redness, sudden pain, or blurred vision are signs of a complication. If you experience any of these issues, remove the lens immediately and consult with an eye care professional.