The expiration date printed on contact lens packaging indicates the final day the manufacturer guarantees the product’s sterility and physical integrity. This date is tied to the sealed blister pack, not the lens material itself, and should be respected without exception. Wearing contact lenses after this date introduces significant risks to eye health and should be avoided entirely.
The Primary Risks of Expired Lenses
The manufacturer’s expiration date guarantees the lens remains in a sterile environment. Over time, the factory seal of the blister pack, typically made of foil and plastic, can degrade microscopically, even if it appears intact. This degradation allows minute amounts of oxygen and potentially harmful microorganisms to breach the sterile barrier.
The saline solution surrounding the lens is also compromised as the expiration date passes. The chemical composition of this sterile solution can shift, losing stability or changing its pH balance, which may alter the lens material. Once sterility is compromised, the lens sits in a potentially contaminated solution, allowing for bacterial or fungal growth.
Beyond contamination, the lens material itself can be affected by prolonged storage past its guaranteed date. The lens may physically warp or become less pliable, which affects the fit and comfort on the eye. Furthermore, the material’s ability to transmit oxygen to the cornea can diminish, setting the stage for serious physiological problems.
Immediate Eye Health Consequences
The most concerning consequence of wearing an expired lens is the increased likelihood of a severe eye infection, particularly microbial keratitis. Contaminated lenses act as a delivery system, placing infectious agents like bacteria directly onto the corneal surface. Keratitis is a painful inflammation or infection of the cornea that can quickly escalate.
A severe and untreated case of keratitis can develop into a corneal ulcer, which is an open sore on the cornea. Bacteria such as Pseudomonas aeruginosa are particularly dangerous, as they can rapidly cause deep tissue damage and scarring. This condition is a medical emergency that can lead to permanent vision loss or even blindness if not treated immediately with targeted antibiotics.
Material degradation in expired lenses can lead to corneal hypoxia, or oxygen deprivation. The cornea is avascular, receiving most of its oxygen directly from the air, a process that a lens can impede. If the expired lens material has lost oxygen permeability, the cornea responds by swelling, a condition called edema.
Prolonged hypoxia can trigger the growth of new, abnormal blood vessels into the cornea, a process called neovascularization, as the eye attempts to compensate for the lack of oxygen. This swelling and vascular growth can lead to blurred vision and, in severe cases, cause irreversible changes to the corneal tissue.
Recognizing Warning Signs and Symptoms
One of the first signs of an issue after wearing an expired contact lens is the sudden onset of redness in the eye, which may resemble conjunctivitis but can indicate a more serious underlying infection.
Discomfort is another common symptom, manifesting as a persistent foreign body sensation or a gritty feeling, suggesting irritation or a scratch on the cornea. You may also experience increased tearing or an unusual, excessive discharge from the affected eye.
As the condition progresses, a noticeable blurriness in vision or an increased sensitivity to light, known as photophobia, can occur. These symptoms indicate that the cornea’s clarity or function is compromised. Any one of these signs following the use of an expired lens warrants an immediate consultation with an eye care professional.
Action Steps After Wearing Expired Lenses
If you realize you have worn a contact lens past its expiration date, remove it immediately. Dispose of the lens and any others remaining in that expired batch to prevent future accidental use. Refrain from putting in any other contact lenses until your eyes have been examined.
Switching to glasses temporarily removes the risk of further contamination or irritation. Even if your eyes feel fine, contact an eye care professional, such as an optometrist or ophthalmologist, to schedule an immediate check-up. This examination is important because contamination can be present without immediate symptoms.
If you are experiencing any redness, pain, discharge, or blurry vision, an emergency appointment is necessary. Do not attempt to self-treat with over-the-counter eye drops or saline, as this may mask symptoms or delay appropriate treatment for a serious infection. Prompt professional intervention is the best way to prevent potential long-term damage and safeguard your vision.