When and how long to wear your lenses
The amount of time different people wear their contact lenses varies, but no lenses should be worn longer than the maximum wearing time recommended by professional who prescribed them. Overwearing lenses is a common cause of problems with contact lenses.
Daily wear
The most common wearing schedule is "daily wear", where the lenses are inserted in the morning, worn through the day, and taken out at night. The lenses are then cleaned and disinfected before being worn again.
Extended wear
Some newer lens types allow wearers to sleep in their contact lenses, either occasionally, or for up to 30 days. This is known as "extended wear". These special lenses allow a large amount of oxygen to pass through the lens, ensuring that the eye receives enough oxygen.
These lenses are not suitable for everyone. Your optometrist can tell you if they would suit your eyes.
You should NEVER sleep in your contact lenses unless your optometrist has specifically advised you that you can do so. Sleeping in the wrong type of lenses can cut off your corneas' oxygen supply while you are asleep, causing severe inflammation and possibly permanent damage.
When to replace your lenses
No contact lens lasts forever, but different types of lenses need to be replaced at different intervals, both because the lenses wear out and to maintain good eye health.
Conventional lenses
Rigid lenses are typically replaced every one to two years. Often the replacement is necessary because the wearer's prescription has changed. Soft lenses (apart from frequent replacement or "disposable" lenses) generally need to be replaced after about one year if they are worn regularly.
Frequent replacement ("disposable") lenses
Most soft contact lenses these days are intended to be replaced at shorter intervals, typically every two to four weeks. This ensures that the lenses are always clean, as they are replaced before any deposits can build up on them. The frequent replacement of lenses has allowed the use of lens materials which are not suitable for long term use. These materials provide good vision and ocular function, but tend to wear out more quickly.