Every packaged product comes with an expiry date. Soft contact lenses should not be treated as a soft story in one’s life. They are serious medical devices that when left unchecked go bad which may lead to vision threatening infections. It is not unusual for contact lenses to come with 3-4 years of shelf life- after the said time has passed; they should be no more considered safe to wear.
Why Do Contact Lenses Expire?
Contact lenses come packed in a seal blister packaging or glass vials. They float into non-preserved buffered saline solution (salt water) and a wetting agent to keep them hydrated. The expiry date is printed on the blister or on the label which must never be neglected. The saline solution responsible to keep soft lenses sterile may go bad over the period of time, if the packaging has received an abuse.
Ruling about Unopened Contact Lenses
Though there are no through research studies that could back the claim of contact lenses going contaminated after the shelf life has been passed; doctors strictly warn consumers against wearing expired contacts- even if they have been sealed tight throughout. A study suggests that contact lens vials/blisters go through enough during transit, cramming & above all mishandling that may compromise the seal and facilitate the transmission of bacteria. Once entered, bacterium can multiply itself in seconds that will leave horrendously gross results on your cornea.
Ruling about Contact Lenses that have been opened but Never Used:
Once opened, the expiry date for annual replacement contact lenses is usually 1 year. Protein buildup, lipids, dust & debris from the environment accumulate over contacts to get rid of which you disinfect them after each wear. Contacts have tiny micro projections that help them to firmly adhere & float on to the surface of the cornea. These very projections facilitate harmful microbes latch on to the contacts & overtime they grow rough due to which even disinfecting them every day becomes useless.
Contact lens manufacturers & eye doctors both view expiry date as something of significance value. As per them; the efficacy of the product cannot be guaranteed after the expiry date has been passed. It is better to toss them off than risking your vision.