Wearing Contact Lenses Overnight - Is It Safe?
Contact lenses have seen a great deal of progress and development from when they were first introduced. With new advances in the silicone material, contact lenses are more comfortable than ever before and cause fewer problems. There are even special extended-wear contact lenses which can actually be worn continuously for up to 30 days and do not need to be removed and cleaned.
For those who want to go to sleep each night with minimal fuss and wake up with bright, clear vision, these are a revolutionary breakthrough. Shift workers in particular may benefit from these lenses, particularly if they are on-call while they are asleep. However only certain lenses, those which allow ample amounts of oxygen to reach the cornea and keep the eyes healthy, have been approved by the FDA for such long term wear. All others should be removed and either discarded or sterilized each night depending upon their recommended lifespan.
Why ordinary contact lenses must be removed each night
If regular lenses are not removed from the eyes at night, the tissue of the eye will not receive adequate oxygen. The eyes may swell up and vision may become blurred. In extreme cases small blood vessels have been known to develop into the cornea to try to supply the required oxygen, and these blood vessels can end up blocking vision permanently. It is therefore not healthy to leave in contact lenses overnight unless they have been specially designed and approved for overnight wear.
In addition, during sleep, bacteria and debris can collect in the eyes. When you are awake, tears constantly flush the eyes but during sleep this does not occur. If regular contact lenses are left in overnight, the eyes may become red, teary and sensitive. You should see an eye doctor immediately if this occurs, as treatment may be necessary.
How are extended-wear contact lenses different?
Extended wear lenses, also called 'continuous wear' lenses, are made from a relatively new material called silicone hydrogel. But not all silicone lenses are created equal. Some types are only approved for 7 day wear while others can be worn for up to a month. It is important to follow the replacement schedule for your particular lenses.
Note that these lenses can be worn for up to one month as long as they remain comfortable. You can change them out more regularly if this practice works better for you.
Problems with extended wear contact lenses
When the first extended wear contact lenses were introduced (before the development of silicone hydrogel), research showed a greater incidence of eye infections in those wearing these lenses overnight compared to those who wore disposables or cleaned their lenses nightly. This caused the FDA to approve the lenses for only 7 day wear and eyecare practitioners, believing any overnight wear to be risky, began encouraging patients to remove their contact lenses each night, even if they were approved for extended wear.
Doctors were concerned were that dangerous organisms could enter the eye and become lodged under the lens. In the warm, moist conditions of the eye, these germs would thrive, and because the contact lens reduces the amount of oxygen reaching the cornea, it would be difficult to fight off the resulting bacterial or fungal infections. Infections ranging from the common “pink eye” to the more serious acanthamoeba keratitis could manifest themselves beneath these old-style extended-wear lenses.
Several changes have now made the wearing of extended wear contact lenses significantly safer.
- Modern extended wear lenses are made of silicone hydrogel which transmits much more oxygen to the eye than conventional soft lenses. This material is what made the FDA approval for 30 day wear possible.
- Today's extended wear lenses are disposable. Previous versions were removed and cleaned in contact lens solution, but it was impossible to remove all the deposits from the lenses. Now a sterile pair of contact lenses is used every time a change is due. This avoids a buildup of residue and reduces the risk of infection.
- Many wearers take a flexible approach to these lenses. They may choose extended wear contacts, but still remove them each night when it's convenient. When nightly cleaning would be too much of a hassle, however, such as during a weekend getaway, they can safely keep them in without any increased risk.
While contact lens technology has improved, wearing contacts overnight still carries a risk of complications. Your chances for infection may be higher if you've had a previous eye infection, or if you expose your eyes to water (such as during swimming) or smoke. In addition, it's essential that the contact lenses be discarded within the time specified by the eye doctor.
You should be aware of the condition of your eyes at all times, and check daily to make sure that they look healthy and feel good, with no signs of redness or irritation. Lenses should be cleaned or replaced whenever necessary to keep the risk of infection to an absolute minimum whilst still benefiting from extended wear contact lenses.
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