Contact lenses have expiration dates. Using lenses past this date risks infection, as the saline solution's pH can change or the blister pack seal may fail, allowing bacteria to enter.
Smaller clinics may have "trial sets" or unsold boxes sitting in their backstock that aren't listed on a website. where to buy discontinued contact lenses
In the US, the FDA regulates contact lenses. A prescription is usually brand-specific and expires after 1–2 years. You cannot legally buy lenses if your prescription for that specific brand has expired. Contact lenses have expiration dates
It is vital to understand the risks and regulations regarding discontinued medical devices: where to buy discontinued contact lenses
If the discontinuation was recent, you might find "leftover" boxes at these types of outlets: