Contact lenses are medical devices that rest directly on the surface of the eye. Because they interact with the body’s delicate ocular environment, their use requires strict adherence to safety guidelines. Ignoring these prohibitions can escalate the risk of serious complications, including painful eye infections, corneal damage, and even permanent vision loss.
Prohibited Water Exposure
Exposing contact lenses to any type of water is a primary source of severe eye infections. You should never wear lenses while swimming in pools, lakes, oceans, or hot tubs, and this ban extends to showering or rinsing your lens case with tap water. Water, even purified drinking water, is not sterile and often harbors microorganisms that can adhere to the lens surface.
The primary pathogen of concern is Acanthamoeba, a microscopic, cyst-forming organism commonly found in soil and water sources, including household tap water. When Acanthamoeba gets trapped between the lens and the eye, it can cause a rare but devastating infection called Acanthamoeba keratitis (AK). This infection targets the cornea, the clear front dome of the eye, and is difficult to treat, often leading to significant vision impairment or blindness.
The contact lens can cause microscopic abrasions on the cornea, providing a pathway for the amoeba to enter. Rinsing your lenses or lens case with tap water is a direct route for introducing this pathogen, and even showering can aerosolize the organism. To prevent AK, lenses must only be cleaned, rinsed, and stored using approved, sterile contact lens solutions.
Mismanagement of Wear Time
A significant risk to ocular health comes from ignoring the recommended wear schedule for your specific lenses. The most common transgression is sleeping in contact lenses, a practice that drastically increases the risk of a vision-threatening infection by six to eight times. This prohibition holds true unless your eye care professional has explicitly prescribed a specific type of extended-wear lens for overnight use.
The cornea, which is the only tissue in the body that receives oxygen directly from the air, relies on this supply to maintain its health and transparency. Wearing a contact lens creates a barrier, and when the eyelid closes during sleep, this oxygen deprivation, known as hypoxia, becomes significantly worse. Chronic hypoxia leads to corneal swelling, or edema, which weakens the cornea’s natural defenses against microbes.
You must never exceed the daily recommended wear time or attempt to extend the replacement schedule for your lenses. Wearing a two-week disposable lens for a month, for instance, allows protein and lipid deposits to build up, creating a more hospitable surface for bacteria. Chronic oxygen deprivation from overwearing can also lead to the growth of abnormal blood vessels into the cornea, a condition called neovascularization, which can permanently impair vision.
Unsafe Handling and Storage Practices
Proper hygiene during handling and storage is paramount, and several practices can compromise the sterility of the lens and case. You should never reuse or “top off” the old disinfecting solution in your lens case. The old solution loses its disinfecting ability quickly and becomes contaminated with proteins and microbes from the eye, transforming it into a breeding ground for bacteria.
It is strictly prohibited to use anything other than a fresh, approved, sterile solution to clean or wet your lenses. The lens case itself is a major source of contamination, as biofilm can form inside it over time. Eye care professionals recommend replacing the contact lens case at least every three months to mitigate the risk of infection.
When using cosmetics, a specific sequence must be followed to prevent product contamination of the lens. You should always insert your contact lenses before applying makeup to avoid transferring oils or pigments onto the lens surface. Similarly, lenses must be removed before taking off makeup, as cleansing products can degrade the lens material or trap particles beneath the lens.
Using Lenses Without Professional Guidance
Contact lenses are medical devices regulated by the Food and Drug Administration (FDA). You must never purchase or wear them without a current, valid prescription from a licensed eye care professional. This prohibition applies to all types of lenses, including decorative or cosmetic lenses that do not correct vision. Purchasing from unauthorized sources risks obtaining counterfeit or non-sterile products.
Even cosmetic lenses require a prescription because they must be properly fitted to the curvature and diameter of your eye. An improperly fitted lens, even one with zero vision correction, can cause physical damage, including corneal scratches, inflammation, and corneal ulcers. The eye care professional measures the cornea to determine the correct base curve and diameter, ensuring the lens fits without restricting oxygen or causing physical irritation.
You must never wear a lens that is visibly torn, chipped, or damaged, as sharp edges can cause trauma to the corneal surface. Sharing lenses with another person is strictly forbidden, as it is a direct way to transfer bacteria, viruses, or other pathogens. Any lens that causes persistent discomfort, redness, or blurred vision should be immediately removed and discarded.