- Some lenses are meant for daily wear. With daily wear soft lenses, you wear the lenses for one day and then discard them. This allows one to dispense with solutions, cleaning, and disinfection of the lenses. It allows intermittent wear such as weekend or occasional wear, as desired. Most soft lenses and some RGP lenses are worn for a day and then removed, cleaned, and disinfected each night. Soft lenses are usually replaced on a regular basis, which varies from one week to one month to three months to one year. RGP lenses may last for years with regular care.
- Extended wear lenses, usually soft, are worn overnight for one week and then replaced every one to two weeks. Trying to extend the wear of lenses beyond the recommended replacement schedule is a false economy and an invitation to potential disaster.
- Overnight wear decreases the amount of oxygen available to the eye and increases the (rare) chance of infection by fourfold. Because of this, some practitioners do not recommend extended wear of contact lenses. Newer lenses may be safer.
Problems resulting from contact lens wear range from the inability to remove the lenses (usually after first being fit) to blindness from infections. Proper fitting, instruction, and care and maintenance can prevent most problems.