Contact lenses replace glasses and are available as one-day lenses, monthly lenses, weekly lenses and three-month lenses. Normally you use the lenses only during the day and not at night. There are special lenses that work even when you sleep. There are also lenses with UV protection and special patterns. Handle-colored lenses do not affect vision, but are easier to see in the lens container. Choose carefully according to strength, size, type of lens and material.