The question of whether one can safely wear expired daily disposable contact lenses is common when a backup box is discovered past its date. Daily disposables are sterile, single-use medical devices intended to be discarded after one day of wear, sealed in a blister pack filled with saline solution. The short answer is definitively no, as the expiration date is a non-negotiable safety deadline. This date represents the final moment the manufacturer can guarantee the lens’s sterility and structural integrity, introducing significant health risks if ignored.
Why Contact Lenses Have an Expiration Date
The expiration date found on a contact lens box and individual blister pack is a regulatory requirement, often labeled as a four-digit year followed by a two-digit month (e.g., YYYY/MM). This date marks the end of the manufacturer’s guarantee for the product’s safety. This guarantee focuses primarily on maintaining the sterile environment within the sealed blister pack.
The lens is suspended in a sterile, buffered saline solution inside a sealed container. Over the typical shelf life of one to four years, the solution and the seal are designed to maintain a pristine, germ-free environment. However, the integrity of the seal can degrade over an extended period, even if the package remains unopened.
The saline solution can also lose its stability and buffering capacity over time. This chemical change can lead to a shift in the solution’s pH, which may damage the lens material. Once the expiration date passes, the possibility of micro-gaps forming in the seal increases, potentially allowing air or bacteria to enter and contaminate the solution and the lens.
The Specific Dangers to Eye Health
Wearing an expired contact lens introduces multiple, serious risks to the delicate tissues of the eye. These dangers stem from the breakdown of guaranteed sterility and material quality. The most significant risk is the increased potential for severe eye infections, collectively known as microbial keratitis.
A compromised seal or degraded solution creates an environment where pathogens, such as bacteria, fungi, or the parasite Acanthamoeba, can multiply on the lens surface. Introducing a non-sterile lens is essentially placing a microbe-laden object directly onto the cornea, which is highly susceptible to infection. These infections can quickly lead to painful conditions like corneal ulcers, which are open sores on the eye’s surface, potentially causing permanent scarring and vision loss.
Beyond contamination, the physical properties of the lens material can change after the expiration date. The material may degrade, becoming less flexible or more brittle, even if the package appears intact. Wearing a brittle or warped lens can cause micro-abrasions or tiny scratches on the corneal surface.
These scratches provide easy entry points for infectious agents. Furthermore, the lens material’s ability to transmit oxygen to the cornea can diminish over time, leading to reduced oxygen permeability. Insufficient oxygen can cause corneal swelling, redness, and irritation, increasing the eye’s overall vulnerability.
Next Steps for Expired Products
If you discover a box of daily contacts that has passed its expiration date, the only safe action is to dispose of them properly. It is important to remove the lenses from their blister packaging before disposal. When flushed, contact lenses do not break down in water treatment plants and contribute to microplastic pollution in waterways.
The best practice is to place the expired lenses directly into your household trash. Many manufacturers and eye care professionals participate in specialized recycling programs that can process contact lenses and their packaging. The cardboard box and any paper inserts can typically be recycled through standard municipal recycling programs.
After discarding the expired supply, contact your eye care professional for a new supply of lenses. This ensures you receive lenses that are guaranteed to be sterile and safe for wear. It is also wise to ensure your contact lens prescription is current, as prescriptions typically expire after one year, requiring an updated eye exam to purchase new lenses legally and safely.