Contact lens

A contact lens (also known as a "contact") is a corrective, cosmetic, or sometimes protective lens placed on the cornea of the eye.

Cleaning and disinfection products

While daily disposable lenses require no cleaning, other types require regular cleaning and disinfecting in order to retain clear vision and prevent infections. There are a number of products that can be used to perform these important tasks:

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• Saline solution - used for rinsing the lens after cleaning and preparing it for insertion.
• Daily cleaner - used to clean lenses on a daily basis. Usually one puts a few drops of cleaner on the lens and rubs for about 20 seconds (check directions) on each side. One must be extra careful in this step if one has long fingernails.
• Multipurpose solution - used for rinsing, disinfecting, cleaning and storing the lenses. Many people typically only use it for disinfection and storage, relying on other products for rinsing (e.g. saline) and cleaning (e.g. daily cleaner).
• Hydrogen peroxide solution - used for disinfecting the lenses. Available as 'two-step' or 'one-step' systems. If using a 'two-step' product, one must ensure that they neutralise any lens taken out of hydrogen peroxide with 'Step 2' before wearing the lens otherwise it can be an extremely painful experience! (do NOT use saline to rinse away the peroxide). Some such solutions, such as CIBA Vision's Clear Care, come with a special storage case that contains a catalyzing disk. If soaked in the solution with the disk for at least six hours, the hydrogen peroxide decomposes and the remaining solution is a simple saline solution that will not harm the eye. This type of cleaning solution is used commonly by people with extremely sensitive eyes that are irritated easily by standard solutions.
• Enzymatic cleaner - used for cleaning the protein off of lenses, usually on a weekly basis. Typically, this cleaner is in tablet form. Using only the daily cleaner is not sufficient to prevent protein deposits, making the lens very uncomfortable and possibly leading to eye damage.

Some products may contain preservatives such as thimerosal. However, about 10% of contact lens wearers have problems with these products, a reason why several brands no longer use it. Such thimerosal-free products are sometimes labelled "for sensitive eyes". Products that do not contain any preservatives usually have shorter expiration dates. For example, non-aerosol preservative-free saline solution typically only last two weeks once opened.

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