Contact lenses are medical devices designed to correct vision, offering a popular alternative to glasses. Eye care professionals uniformly advise against wearing most types of lenses while asleep. This recommendation is based on significant health hazards that arise when the lens remains under a closed eyelid. Failing to remove lenses before bed dramatically increases the risk of eye complications, ranging from mild irritation to severe, vision-threatening infections.
The Role of Oxygen Deprivation
The clear front surface of the eye, the cornea, must draw nearly all its oxygen directly from the surrounding air. When the eye is open, this process maintains corneal health. During sleep, the cornea relies on a reduced oxygen supply from the blood vessels in the inner eyelid.
Placing a contact lens over the cornea creates a physical barrier that further restricts this limited oxygen flow, leading to hypoxia. This lack of oxygen causes the cornea to swell, a reaction known as corneal edema. Edema makes the corneal tissue more fragile and susceptible to damage. While some “extended wear” lenses are highly permeable, they still do not eliminate the underlying risks of overnight wear.
Increased Risk of Serious Eye Infections
The physiological stress caused by hypoxia contributes to a significantly higher risk of serious eye infections. Sleeping in any type of contact lens increases the likelihood of developing microbial keratitis, a severe corneal infection, by six to eight times. This is because the lens traps bacteria, dirt, and debris that naturally accumulate on the eye’s surface against the vulnerable corneal tissue.
The lens also impedes the normal flushing action of tears, which typically wash away these pathogens. When the cornea is weakened by oxygen deprivation and overwhelmed by trapped microorganisms, the bacteria can penetrate the surface and cause a painful, rapidly progressing corneal ulcer. These ulcers can be caused by common bacteria like Pseudomonas aeruginosa and require immediate treatment with powerful antibiotic or steroid drops.
A particularly dangerous risk is infection by Acanthamoeba, a microscopic organism often found in water sources that can adhere to contact lenses. Acanthamoeba keratitis is rare but can be devastating, causing severe pain and potentially permanent vision loss due to scarring, often requiring a corneal transplant. The combination of a compromised corneal surface and the presence of pathogens under the lens creates an ideal environment for these vision-threatening infections to take hold.
What to Do If You Accidentally Sleep in Lenses
If you wake up realizing you have slept in your contact lenses, the most important step is to avoid immediately pulling them out. The lens will likely be dehydrated and stuck tightly to the cornea, and forcing removal can cause a painful abrasion on the corneal surface. Instead, you should first rehydrate the eye by applying a few drops of sterile saline solution or contact lens rewetting drops.
Gently blink several times to allow the lubricating fluid to work its way between the lens and the eye. After waiting about 20 to 30 minutes, the lens should have loosened enough to be removed safely and easily. You must discard the worn lenses and allow your eyes to recover by wearing glasses for the rest of the day.
If you experience persistent redness, pain, excessive watering, or blurred vision that does not resolve quickly, contact your eye care professional immediately, as these are signs of a potential infection.