Contacts do not last forever. Each brand of contact lens has a specifically recommended replacement schedule based on the ability of the lens to transmit oxygen and to shed proteins from the surface. Most contact lenses sold in the US today are either daily disposable, 2 week disposable or monthly disposable lenses.
Most disposable contacts are designed to be worn from one day to one month, depending on the lens material. They often have high water content and are usually made with thinner, more flexible materials. One-day contacts are disposed of after each use but longer term disposable contacts must be cleaned and disinfected after each removal. Disposable contacts can be prescribed for daily use or extended wear, depending on the brand and purpose in question.
Disposable daily wear lenses first became available in 1987 and exploded in popularity soon after in the 1990s. Daily wear two-day lenses were introduced in 1991, followed by tinted disposable lenses in 1992, one-day disposable lenses in 1995 and multifocal disposable lenses in 1998.
Conventional contacts are generally worn from six months to a year, and are not frequently prescribed due to the improvements in disposable lenses. They are produced in daily wear and extended wear models and can be soft lenses, hard lenses or rigid gas permeable lenses.
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