Contact lenses are medical devices that come with an expiration date printed on their packaging. This date indicates the period during which the product is guaranteed to be safe and effective. Adhering to this date is important for maintaining eye health and avoiding potential complications.
Immediate Discomfort and Irritation
Wearing contact lenses past their expiration date can lead to immediate, noticeable symptoms. These often include redness, a scratchy sensation, dryness, a burning feeling, or itching. The lenses themselves may become less comfortable, feeling rougher due to material breakdown. Blurred or cloudy vision can also occur as the lens material degrades or deposits accumulate on the surface. These irritations often stem from reduced oxygen permeability or the buildup of proteins on the lens surface.
Serious Ocular Complications
Beyond immediate discomfort, wearing expired contact lenses can lead to severe ocular complications that may threaten vision. Expired lenses are more susceptible to bacterial contamination, increasing the risk of infections such as bacterial keratitis, an infection of the cornea. This condition can cause significant pain and may result in corneal ulcers, which are open sores on the eye’s surface that can lead to permanent scarring and vision impairment.
Fungi can also grow on expired lenses, potentially leading to serious fungal infections like fungal keratitis, which are challenging to treat and can damage vision. Another serious risk is Acanthamoeba keratitis, caused by a microscopic organism found in water and soil. This parasitic infection is associated with poor lens hygiene and expired products, potentially leading to severe vision loss or blindness.
Prolonged wear of expired lenses can also lead to corneal neovascularization, a condition where new blood vessels grow into the cornea. This occurs when the cornea is deprived of oxygen, prompting new vessel growth. These new vessels can block light, potentially causing hazy vision or decreased visual sharpness, and in severe cases, permanent vision impairment. Giant papillary conjunctivitis, an allergic reaction characterized by bumps on the inner eyelid, can also develop from protein deposits and degraded materials on old lenses.
The Science Behind Expiration
The expiration date on contact lenses primarily refers to the sterility of the saline solution they are packaged in, rather than the lens material itself. Lenses are manufactured in a sterile environment and sealed in airtight blister packs with saline solution. Over time, typically between one to four years from the manufacturing date, the active ingredients within this solution can degrade, losing their ability to maintain a sterile environment.
After the expiration date, the blister pack seal may also lose integrity, even if not visibly apparent. A compromised seal allows oxygen and microorganisms, such as bacteria and fungi, to enter and contaminate the lens. This contamination creates a breeding ground for harmful pathogens. Additionally, the lens material itself can undergo subtle changes in its physical properties, such as losing its optimal shape or elasticity, making it less comfortable and effective for vision correction.
Steps After Wearing Expired Lenses
If you realize you have worn expired contact lenses, immediately remove and discard them. Do not attempt to clean or reuse these lenses. Even if no immediate symptoms of irritation or infection are present, consulting an eye care professional, such as an optometrist or ophthalmologist, is advised.
An eye care professional can examine your eyes for any signs of irritation, damage, or early-stage infection that might not be readily apparent. Early detection of complications is important for effective treatment and preventing more severe issues. Avoid self-treating any symptoms and seek professional medical guidance, especially if experiencing persistent discomfort, redness, blurred vision, or unusual discharge.
Maintaining Lens Safety
To prevent issues associated with expired or improperly used contact lenses, follow several safety practices. Always check the expiration date on the packaging before use, even for unopened boxes. Adhere strictly to the prescribed wearing schedule, whether lenses are daily disposables, bi-weekly, or monthly, and never extend their use beyond the recommended period.
Proper cleaning and storage routines are also important for reusable lenses. Wash hands thoroughly before handling lenses, use only fresh, unexpired contact lens solution for cleaning and disinfection, and never use tap water. Clean the lens case daily with fresh solution, allow it to air dry, and replace it regularly, typically every three months. Regular eye examinations with an eye care professional are important to monitor eye health and ensure continued suitability of contact lenses.