Contact lens cases should be changed at least every three months, however monthly is preferably. Many contact lens solutions come with a fresh case, so you can dispose of your old case every time time you start a new bottle.
John Gallagher from the American Academy of Ophthalmology said contact lens cases are designed to be disposable for hygiene reasons.
His comment was left on the Democrat Herald website in response to a blog post by Steve Lundeberg, which described how he was inadvertently collecting contact lens cases.
Mr Lundeberg admitted he had around 20 cases littering his bathroom and his wife had questioned his need for them.
He explained he got given a new one each time he ordered his contact lenses but he was not sure why, "because its not like they ever wear out or otherwise go bad".
However, Mr Gallagher replied the reason was so germs did not build up in the old cases and cause an eye infection.
"After three months, you should toss the case," he said.
"Old and dirty cases can be a source of contamination that can lead to serious eye infections."
Contact lenses can be ordered online with the help of a prescription.
by Adrian Galbreth