Sleeping With Contacts: Risky Business For Your Eyes

Sleeping with contact lenses in your eyes can lead to some serious eye complications. While it may be tempting to fall asleep without removing them first, it is important to understand the potential risks involved. Contact lenses impede the cornea's access to oxygen, and when the eye is closed, the lens acts as a barrier, blocking both oxygen and tears from reaching the corneal surface. This can lead to hypoxia, inflammation, abnormal blood vessel growth, and even corneal abrasions. Additionally, the constant adhesion of the lens to the cornea can result in microbial infections, with keratitis being the most common infection associated with extended contact lens use.

Hypoxia and corneal damage

Hypoxia is a state of metabolic distress occurring in living tissue when its oxygen supply is reduced to a level that can no longer support normal aerobic respiration in its cells. In the context of the human eye, hypoxia occurs when the cornea does not receive enough oxygen. The cornea, which is the outermost layer of the eye, relies primarily on atmospheric oxygen to maintain its health.

The cornea is unique among the body's tissues in that it is transparent. This transparency is dependent on the cornea's water content, which is substantially less than its surroundings. The cornea maintains its dehydrated state through an active pumping mechanism located in the endothelium, a single layer of cells that forms the cornea's posterior surface. The endothelium is highly dependent on aerobic metabolism to satisfy the energy demands of its pumping mechanism.

When contact lenses are worn for extended periods, they act as a barrier to the oxygen supply of the cornea. This can lead to corneal hypoxia, causing the cornea to swell as it starts to accumulate lactic acid, which pulls water towards it, resulting in edema. While the initial symptoms of corneal hypoxia may seem mild, there is a potential for more serious problems, including the development of corneal cysts and the death of epithelial cells, both of which can compromise vision.

Sleeping with contact lenses increases the risk of corneal hypoxia because the closed eyelids further reduce the oxygen available to the cornea. This can have serious consequences for eye health, including an increased risk of eye infections, lens displacement, and dry eyes.

Increased risk of eye infections

Sleeping with contact lenses in your eyes increases the risk of eye infections, particularly microbial keratitis. This can cause vision loss and permanent scarring. Studies show that wearing contacts overnight increases the risk of eye infections by over five times, regardless of the type of lens used. The CDC reports that sleeping with contacts can increase your chance of contracting an infection by six to eight times.

Your eyes need a constant supply of oxygen and hydration to stay healthy. Contact lenses can limit the amount of oxygen and moisture that pass through to your eyes. This can cause your eyes to become dry and sticky, making the lenses difficult to remove.

Throughout the day, blinking helps to generate tears and hydrate your eyes naturally. When you sleep, you don't blink, so there are two forms of dehydration going on in your eyes, which won't just cause discomfort but could also lead to serious, long-lasting issues.

Types of Eye Infections

Bacterial Keratitis

Bacterial keratitis is an infection of the cornea, generally resulting from either Staphylococcus aureus or Pseudomonas aeruginosa, both of which are bacteria found on the human body and in the environment. Bacterial keratitis can be treated with aggressive antibiotics, but whether it causes long-term vision issues depends on the situation.

Acanthamoeba Keratitis

Acanthamoeba keratitis is an infection caused by a tiny, single-celled organism called Acanthamoeba, which can be found in natural bodies of water, soil, tap water, heating and air conditioning systems, and hot tubs. This type of infection is often associated with poor contact lens hygiene, such as swimming or showering while wearing contact lenses.

Fungal Keratitis

Fungal keratitis is caused by an infection of the cornea by fungi. It is more common in tropical areas but can occur in any climate. It is treated with antifungal medicine, but more severe cases may require surgery or a corneal transplant.

What to Do if You Sleep with Contact Lenses In

If you accidentally sleep with your contact lenses in, don't panic. Here are the steps you should take:

• Allow your eyes to breathe and rehydrate by blinking and applying rewetting drops.
• Rest your eyes by avoiding contact lenses for 24 hours to recover from redness, dryness, and irritation.
• Consult your eye care professional if persistent eye pain, redness, or irritation persists.

Contact lenses get dirty

Contact lenses can get dirty in a number of ways, and it's important to keep them clean to avoid eye infections. Firstly, your hands can introduce bacteria and germs to your lenses, which can cause an infection. This can happen when you're handling your lenses to put them in or take them out, so it's important to wash your hands with mild soap and dry them with a lint-free towel before touching your lenses.

Secondly, contact lenses should always be stored in contact lens solution. Never use water or saliva to clean or store your lenses, as this can cause serious infections. It's also important to use fresh solution each time, rather than topping up the existing solution in your case. The case itself should be sterilised daily and replaced every three months, or as recommended by your eye doctor.

Thirdly, contact lenses should never be exposed to water, for example when swimming, showering, or bathing. This can contaminate your lenses and cause infections.

Finally, it's important to rub your lenses clean with contact solution and to follow the instructions for disinfecting and storing your lenses. This should be done every time you wear them, and lenses should be replaced as often as recommended by your doctor.

Risk of corneal ulcers

Corneal ulcers are open sores on the cornea, the thin, clear layer over the iris (the coloured part of the eye). They are considered a medical emergency and can lead to permanent eye damage, low vision, and even blindness.

Contact lens wearers are more likely to get corneal ulcers, with the risk being 10 times higher for those who use extended-wear (overnight) soft contacts. This is because wearing lenses for long periods can block oxygen from reaching the eyes, and bacteria can get trapped under the lens. Specifically, wearing contacts overnight can reduce the amount of oxygen reaching the cornea by up to 80%, impairing its ability to protect itself from microorganisms.

Bacteria on the lens, transferred from the finger when inserting the contact, or from non-sterile cleaning solutions, can get trapped under the lens and lead to infection. This risk occurs regardless of the type of lens—soft, hard, decorative, or prescription. Even occasional or accidental sleeping in lenses can increase the risk of infection.

In addition, scratches on the edge of the contact might scrape the cornea and leave it more open to bacterial infections. Tiny particles of dirt trapped under the contact could also scratch the cornea.

Corneal ulcers can also be caused by:

• Eye injuries
• Exposure (inability to close the eyes fully)
• Very dry eyes
• Toxic effects from substances or medications
• Immune conditions

Symptoms of corneal ulcers include:

• Red or bloodshot eye
• Watery eye
• Severe eye pain
• Pus or other eye discharge
• Feeling like something is stuck in the eye
• Light sensitivity
• Inflamed or swollen eyelids
• A white or gray spot on the cornea

If you accidentally fall asleep with your contacts in, remove them as soon as possible. If they feel stuck, do not pull at them. Instead, use eye drops and blink until they can be removed easily. Then, give your eyes a break by avoiding contact lenses for at least a day.

Potential for permanent vision loss

Contacts are designed to be worn during the day and taken out at night. While some lenses are FDA-approved for overnight use, the Centers for Disease Control and Prevention (CDC) warns that sleeping with your contacts in makes you six to eight times more likely to suffer from a corneal infection. Infections in the eye can be uncomfortable, and they can also cause permanent vision loss.

Oxygen Deprivation

The cornea of your eye relies on oxygen from the atmosphere, which dissolves in the tear film that coats your eye. When there isn't enough oxygen supply, corneal cells can get damaged, leading to various symptoms and complications. Contact lenses add an extra barrier that blocks oxygen from reaching the eye.

Risk of Infection

Many bacteria and microorganisms come into contact with our eyes. Wearing contacts while you sleep can trap these bacteria in your eyes and lead to various infections. The longer you keep them in your eyes, the longer the bacteria can grow unimpeded.

Corneal Ulcers

Regularly sleeping with contact lenses can lead to corneal ulcers, which are open sores on the cornea. This painful condition can cause significant vision impairment or even permanent vision loss if not treated quickly and appropriately.

Eye Conditions

Sleeping with contact lenses can also lead to several specific eye conditions, including:

• Contact lens acute red eye (CLARE)
• Giant papillary conjunctivitis (GPC)
• Debris and dirt getting trapped underneath the lenses

Sleeping with your contacts in can be dangerous and can lead to permanent vision loss in some cases. It is important to follow the instructions for your specific type of contact lens and to practice good lens hygiene to protect your eyes from infection and other complications.

Frequently asked questions