According to the University of Michigan Kellogg Eye Center, approximately 24 million Americans wear contact lenses. The style of contacts varies, as does the length of time that each style can be worn. The original contacts that were introduced in the 1950s were known as "hard contacts," which were uncomfortable and deprived the cornea of oxygen. The vast majority of users have since replaced hard contacts with "soft contacts" that are breathable and allow for longer, comfortable wear. But the amount of time that any set of contact lenses can be worn depends on the type of material the lens is made of.
Single-Use Soft Contacts
Single-use disposable soft contacts are comfortable and convenient. They are made of soft, flexible plastic that is meant to be used and then thrown away. They are the most expensive type of soft contact lenses, and are often packaged in pairs that are already soaked in a sanitary solution. According to Today's Vision, single-use contacts are designed to be worn throughout the day and then discarded at bedtime.
Daily Wear Soft Contacts
Just as single-use soft contacts are designed for daily use, daily wear soft contacts are too. But there is one major difference. Daily wear soft contact are intended to be taken out at bedtime and instead of being thrown away, they are to be placed in cleaning solution to prepare them for use the following day. The Mayo Clinic explains that daily wear soft contacts are intended to be used for several weeks before being discarded. How many weeks strictly depends the manufacturer's instructions and the doctor's recommendations.
Extended Wear Soft Contacts
Extended wear soft contacts are made of a special plastic that is oxygen permeable, allowing the cornea of the eye to breathe. All About Vision reports that the breathability factor makes extended wear contacts safe to sleep in, and depending on the manufacturer, extended wear soft contacts can be worn continuously for a week. There is even one major brand that manufactures extended wear soft contacts that are intended for continuous wear for up to 30 days.
Gas Permeable Contact Lenses
Gas permeable (GP) contacts are a combination of both hard and soft contacts. GP contact lenses are also known as "rigid" lenses and are considered to be highly durable. According to Lens Shopper, the GP lenses are designed to be used for three to six months, and taken out every evening to be cleaned and soaked overnight.
Wearing a set of contact lenses longer than intended by the manufacturer can lead to serious eye injury. Dry eyes, blurred vision, pain and redness can occur, which can later manifest into a full-blown infection. Brigham and Women's Hospital explains that microscopic bacteria can also develop on the lens over time, causing damage to the cornea and eye ulcerations. If any of these problems happen to develop, medical attention should be sought immediately by an eye professional.