7 Real Dangers That Come from Sleeping in Contacts

It’s estimated that around a third of all contact lens wearers sleep with their lenses in. But while most can wake up with nothing more than a little dryness in their eyes when using standard lenses, some may find that their lenses cause significant problems for their eyesight and comfort levels. These are seven real dangers that come from sleeping in contacts.

1. Hypoxia

Our corneas come into contact with bacteria every day, but infections rarely occur since the eye has natural defences against contaminants. However, hydration and oxygen are essential for the cornea to work properly and maintain these defences. When you’re awake, blinking keeps the eyes moist and healthy, and oxygen is able to flow through the tears we produce to enhance this lubrication. 

But when you’re wearing contacts, the amount of oxygen and moisture your eyes can receive is significantly reduced – couple this with sleeping, and your risk of infection increases because the cornea can’t fight bacteria as effectively. This state of no oxygen is known as hypoxia.

2. Bacterial Keratitis

Bacterial keratitis is an infection to the cornea caused by Staphylococcus aureus or Pseudomonas aeruginosa, which are found on the body and in the environment naturally. If you wear contacts for a long period of time, you’re more likely to develop keratitis – a compromised immune system, or an eye injury can also increase your chances. Bacterial keratitis can be treated by eye drops in most cases, but if left untreated, it could cause permanent scarring to the cornea. 


3. Corneal Ulcers

Wearing your lenses for too long can increase the chances of you developing corneal ulcers, which are open sores which form on the surface of the cornea. The reason for this is that lenses can scratch the surface of the eye which leaves it open to infection, and microscopic particles can then become trapped beneath the lens. In severe cases, corneal ulcers can require a corneal transplant. 

Studies suggest that people who sleep in their lenses regularly are up to five times more at risk of developing corneal infections. Signs of a corneal ulcer include redness, severe pain, blurred vision, discharge from the eye and a feeling as though there’s something in your eye all the time. 

4. Parasites

If you regularly sleep in your lenses, for months at a time, you could be putting yourself at risk of becoming infected with Acanthamoeba – a parasite which can cause serious infections in the eyes, skin and central nervous system. You may notice that your eye becomes swollen and develops a discharge, along with sensitivity to light and a stabbing sensation in your eye. It’s essential that you get seen by your doctor if you suspect that you might have developed this infection.

5. Conjunctivitis

Conjunctivitis, more commonly referred to as pink eye, is a common infection and considerably less dangerous than other infections in this list. It’s an inflammation of the conjunctiva which covers the white of the eye and lines the inside of the eyelid. 

Conjunctivitis is caused by a viral infection and leads to the eyes becoming itchy and uncomfortable. Contact lenses are commonly affected by this infection, as the lens can become covered with bacteria which spreads to the eye itself.

6. Corneal Neovascularisation

Corneal neovascularisation is an issue that is caused by a loss of oxygen to the eye. Wearing contact lenses overnight prevents the eye from getting oxygen, which causes the eye to grow more blood vessels to compensate and increase the supply of blood to the cornea. The long-term impact is impaired vision caused by the vessels inhibiting the amount of light that can travel to the cornea.

7. Fungal keratitis

Fungal keratitis is common in areas where temperatures are warmer, or in tropical locations, but the risk can be increased by wearing your lenses when you sleep. Most people who develop fungal keratitis have also suffered some form of eye trauma, from the likes of a plant or branch. It’s important to seek treatment if you develop fungal keratitis, as if it’s left, it can lead to a loss of sight in the infected eye. 

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How to maintain good hygiene when wearing lenses

Contact lenses are a convenient alternative to glasses that can be great for active people or those who don’t like the appearance of glasses. But maintaining good hygiene is essential to prevent infections from developing. In addition to taking your lenses out before you go to sleep, you also need to clean them thoroughly with fresh saline solution if you’re using reusable lenses, or switch to a new pair every day if you use disposables. Never wash your lenses in water and don’t shower or swim with your lenses in. 

Make sure your hands are thoroughly clean and dry before handling your lenses and store them in a clean storage container that’s filled with fresh saline solution every time. If you’re finding maintaining your lens routine too difficult or time-consuming, it may be worth speaking to your optician about switching to disposables which take some of the hassle out of the routine.

Final thoughts

While we can all get forgetful and sleep in our contact lenses occasionally, the risk of doing so regularly can significantly increase your chances of developing an issue. When you’re asleep, you’re preventing oxygen from getting to your eyes if your lenses are still in, and this can cause infections and vision problems to develop. 

If you do happen to fall asleep with them in, make sure you remove them as soon as possible and let your eyes recover for a day or two before wearing your contacts again. It’s also important to get your eyes checked regularly and see a doctor straight away if you note signs of an infection developing.