Sleeping in contact lenses, even just for a nap, dramatically increases the likelihood of developing an eye infection, including conjunctivitis (pink eye). This practice disrupts the delicate biological balance of the eye, increasing the risk of infection by six to eight times. This creates a prime environment for microorganisms to thrive and cause damage. Understanding how this seemingly minor habit compromises eye health is the first step toward preventing potentially vision-threatening complications.
How Sleeping in Lenses Creates Risk
The cornea relies on oxygen absorbed directly from the air to remain healthy since it lacks its own blood vessels. A contact lens acts as a physical barrier that restricts this oxygen flow, which is normally delivered via the tear film. Closing the eyelids during sleep further limits available oxygen, causing corneal hypoxia, or oxygen deprivation.
This lack of adequate oxygen causes the corneal epithelial cells to swell, compromising the integrity of the cornea’s protective outer layer. A weakened epithelial barrier makes the eye highly vulnerable to invasion by bacteria and other pathogens that are normally kept at bay by a healthy corneal surface and tear fluid. The lens itself also traps debris, old tear proteins, and microorganisms between its surface and the cornea.
Over time, this trapped material, along with bacteria introduced during handling, forms a sticky, protective layer on the lens known as a biofilm. This biofilm is a breeding ground for pathogens that resists the eye’s natural defenses and even some disinfecting solutions. Wearing a lens covered in this microbial layer overnight presses the concentrated source of infection directly against the compromised corneal tissue, significantly raising the risk of severe infection.
Understanding Conjunctivitis (Pink Eye)
Conjunctivitis, commonly called pink eye, is an inflammation of the conjunctiva, the thin membrane covering the white part of the eye and the inner surface of the eyelids. Symptoms typically include redness, a gritty sensation, itching, and increased tearing. Depending on the cause, the eye may also produce a watery, mucous, or thick, pus-like discharge.
While conjunctivitis can be caused by viruses, allergens, or irritants, the type most often associated with poor contact lens hygiene and overnight wear is bacterial conjunctivitis. Bacteria such as Staphylococcus or Streptococcus can be transferred to the eye via contaminated lenses or lens cases. This form is highly contagious and requires the immediate discontinuation of contact lens wear, often along with antibiotic treatment, to resolve.
The inflamed conjunctiva interacts directly with the lens, which can further irritate the eye and prolong the infection. If pink eye develops, the wearer must discard the lenses, solution, and potentially the case to prevent reinfection. Failing to remove lenses when symptoms appear can also spread the infection from one eye to the other through handling.
Beyond Pink Eye: Other Serious Infections
While pink eye is a common consequence of contact lens misuse, it is often the least severe outcome of sleeping in lenses. The most serious and vision-threatening complication is infectious keratitis, a condition where the cornea itself becomes infected and inflamed. This deep-tissue infection can quickly progress into a corneal ulcer, which is an open sore on the eye’s surface.
Corneal ulcers caused by contact lens misuse are frequently attributed to aggressive bacteria such as Pseudomonas aeruginosa, which can cause significant damage to the cornea within 24 hours. Another severe threat is Acanthamoeba keratitis, a painful and difficult-to-treat parasitic infection linked to lenses exposed to tap water or showering. Both of these infections are considered ocular emergencies requiring immediate and aggressive treatment.
Untreated or rapidly progressing keratitis can lead to permanent scarring of the cornea, which directly interferes with vision and may ultimately require a corneal transplant to restore sight. Recognizing the symptoms of a serious infection is important. These symptoms include extreme eye pain, significant light sensitivity, and a visible white or gray spot on the cornea.
Essential Rules for Safe Contact Lens Wear
The simplest and most effective rule for safety is to always remove all contact lenses before sleeping or napping, unless specifically approved by an eye care professional for overnight wear. Even approved extended-wear lenses carry a higher risk of infection than daily-wear options, making nightly removal the preferred standard.
Proper hygiene must be followed every time lenses are handled to avoid introducing pathogens to the eye. This begins with washing hands thoroughly with soap and water, then drying them completely with a clean, lint-free towel before touching the lenses. Never use tap water or saliva to rinse or store lenses, as water contains microorganisms, including Acanthamoeba, that can cause severe infections.
When cleaning reusable lenses, always use fresh, approved contact lens solution, making sure to rub and rinse the lens according to the manufacturer’s instructions. Never “top off” old solution with new solution, as the disinfecting power of the old liquid is diminished and may be contaminated. The lens case should also be rinsed with fresh solution, allowed to air dry completely, and replaced entirely at least every three months.