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Extended Wear Contact Lenses

By Gary Heiting, OD

Extended wear contact lenses may be the right option for you if you would like to wake up each day with clear vision.

Contact lenses are available for two different wearing schedules:

• daily wear (you remove them before sleeping)
• extended wear (you leave them in overnight)

In the United States, the FDA has approved some contact lenses for daily wear only and others for extended wear. Extended wear lenses allow more oxygen to reach your cornea.

Most extended wear (EW) lenses today are made of silicone hydrogel lens materials that allow significantly more oxygen to reach the front surface of the eye, compared with earlier soft (hydrogel) lens materials.

Several extended wear lenses are FDA-approved for up to seven days of continuous wear, and at least two brands of silicone hydrogel EW lenses — Air Optix Night & Day (CIBA Vision) and PureVision (Bausch + Lomb) — are approved for up to 30 days of continuous wear.

Also, some gas permeable lenses have received FDA approval for up to 30 days of continuous wear.

With extended wear contact lenses, you can wake up in the morning with clear vision.

It's important to note that these are the maximum wearing schedules allowed. Many people cannot tolerate wearing EW lenses for this length of time, and some people's eyes cannot tolerate any overnight wear of contact lenses.

During your contact lens fitting and follow-up, your optometrist or ophthalmologist will advise you whether you can wear EW contacts overnight and how many days of continuous wear your eyes can tolerate.

Recently, an international survey of contact lenses prescribed for extended wear in 2006 to 2010 found that:

• 71 percent were spherical lenses to correct nearsightedness or farsightedness.
• 14 percent were toric lenses for astigmatism (with or without nearsightedness or farsightedness).
• 10 percent were multifocal lenses for presbyopia.

The same survey found that the majority of extended wear lenses (66 percent) were designed for monthly replacement; approximately 18 percent were for 1-2 week replacement.

Risks of Extended Wear Contacts

The FDA first approved certain contact lenses for overnight wear in 1981. These lenses were approved for up to two weeks of wear without removal. Shortly thereafter, some lenses received FDA approval for up to 30 days of continuous wear.

Researchers found, however, that the incidence of eye infections was greater among people who slept while wearing contact lenses. In response, the FDA changed the maximum extended wear period to seven days.

However, many eye care practitioners decided that any overnight wear was too risky, and they began encouraging patients to always remove their contacts before sleep, even if the lenses were FDA-approved for extended wear.

Extended wear lenses are a concern because bacteria and other potentially dangerous microorganisms can adhere to the lenses and get trapped between the lenses and your eyes. These microbes thrive in the warm, moist environment under your contact lenses, especially when your eyelids are closed during sleep. And because contact lenses reduce the oxygen supply to your corneas, your eyes are less able to fight off infections.

Contact lens-related infections can range from an annoying case of pink eye to more serious conditions such as Acanthamoeba keratitis and fungal eye infections that can cause permanent vision loss. If you wear contacts continuously for several days, your risk of these problems increases significantly.

New Extended Wear Lenses

Advances in contact lens technology have made new extended wear contact lenses safer than previous lenses prescribed for continuous wear.

Also, eye care practitioners generally are taking a more cautious approach to patient selection and wearing recommendations to reduce the risk of eye problems from continuous wear of contact lenses.

These advances and new approaches to extended wear include:

• Most modern extended wear lenses are now made with silicone hydrogel lens materials that allow significantly more oxygen to pass through the lenses to the eye than previous EW lenses.This decreases the risk of hypoxia that makes the cornea more susceptible to inflammation and infection.
• Nearly all soft lenses prescribed for extended wear today are disposable contacts that are discarded at two-week or monthly intervals. More frequent replacement of EW lenses reduces the build-up of proteins, lipids and other lens deposits that cause eye inflammation and discomfort and create a hospitable environment for the growth of infection-causing microorganisms.
• Extended wear lenses also are available in new rigid gas permeable (GP) lens materials. Some eye care practitioners prefer GP lenses for extended wear because they cover less of the eye and, because they move more with each blink than soft EW lenses, there is less risk of debris and infection-causing microbes getting trapped behind the lenses.
• Many eye care practitioners are recommending "flexible wear" of extended wear contacts rather than wearing the lenses continuously for several days without a break. In flexible wear, disposable EW lenses usually are removed at night before sleep, but can be worn overnight occasionally — during a weekend camping trip, for example, or for daytime naps. Though flexible wear is not quite as convenient as extended wear (proper lens care using an approved contact lens solution is required each time the lenses are removed), it may be less risky than full extended wear.

Extended Wear Safety

Despite these improvements, wearing contact lenses during sleep still carries a greater risk of complications than removing your lenses daily. For this reason, most eye care practitioners prefer daily wear lenses for their patients.

In a study of contact lens fittings by eye care professionals in 39 countries over a 14-year period ending in 2010, researchers found that use of EW contact lenses peaked in 2006, when approximately 12 percent of all soft contact lens prescriptions were for extended wear lenses.

In 2010, approximately 7.8 percent of worldwide contact lens fittings were for extended wear lenses. The rate was highest in Norway, with 27 percent; in the United States, EW lenses accounted for about 10 percent of soft contact lens fittings.

The reason for the decline in use of extended wear lenses from 2006 to 2010 might be due in part to increased use of daily disposable contact lenses. These daily wear lenses are removed and discarded each night before sleep, and (like disposable extended wear lenses) they offer the convenience of not requiring daily cleaning and disinfection with contact lens solutions.

Also, some candidates for extended wear contacts are instead choosing LASIK and other types of refractive eye surgery to eliminate their need for prescription eyeglasses and contact lenses.

Eye infections and other complications of contact lens wear often are caused by failure to clean and disinfect the lenses after each use. You can bypass the need for daily lens care by wearing extended wear contacts continuously, but it's critical to discard your lenses as instructed by your eye doctor and not exceed the maximum wearing schedule your doctor recommends.

Usually this means replacing your lenses weekly, every two weeks or monthly (depending on the type of lenses you have), and sleeping without your lenses on at least once a week.

Keep in mind that exposure to smoke, wearing your contacts while swimming or relaxing in a pool or hot tub, dry eyes and previous eye irritations or infections are additional risk factors for extended wear contact lens complications.

Another way to avoid a problem with extended wear lenses is to "listen" to your eyes and take action, if necessary. Every day, take a good look at your eyes in a mirror. They should always:

• Look good
• Feel good
• See well

If you experience red or irritated eyes or reduced vision that does not improve with fresh lenses or lens cleaning, remove your lenses and consult your eye doctor immediately.

About the Author: Gary Heiting, OD, is senior editor of AllAboutVision.com. Dr. Heiting has more than 25 years of experience as an eye care provider, health educator and consultant to the eyewear industry. His special interests include contact lenses, nutrition and preventive vision care. Connect with Dr. Heiting via Google+.

[Page updated March 2012]