Contact Lens Wearing Time

Until 1979, everyone who wore contact lenses removed and cleaned them nightly. The introduction of "extended wear" enabled wearers to sleep in their contacts. Now, two types of lenses are classified by wearing time:

1. Daily wear — must be removed nightly
2. Extended wear — can be worn overnight, usually for seven days consecutively without removal

"Continuous wear" is a type of extended wear lens that can be worn for 30 consecutive nights.

Disposal Intervals for Contact Lenses

One problem with soft contact lenses is that proteins and lipids — which are naturally found in tears — adhere to the surface of the lens, sometimes causing discomfort and providing hiding places for infection-causing germs.

Lens-cleaning products help. But over time buildup still occurs, necessitating lens replacement. Disposable lenses, first introduced in 1987, address this problem in different ways. (Note that, although "disposable" generally means single-use, this is not not always true regarding contact lenses.) Here are the options:

• Daily disposable — replaced every day
• Disposable (used for daytime wear) — replaced every two weeks
• Disposable (used for overnight wear) — replaced every week
• Continuous wear (used for 30-day wear) — replaced monthly
• Planned replacement — replaced monthly or less frequently

By, Liz Segre