Contact lenses are medical devices that offer a convenient alternative to eyeglasses, but their use requires strict adherence to care and safety guidelines. While modern lenses are safe and effective, certain activities and practices are strictly forbidden because they significantly increase the risk of serious complications. Ignoring these prohibitions can lead to severe eye infections, inflammation, and potential vision-threatening damage to the delicate structures of the eye. Maintaining clear and healthy vision depends entirely on understanding and following the absolute limits of contact lens wear.
Prohibitions Related to Water Exposure
You must never expose your contact lenses to any form of water, including when swimming, showering, or using a hot tub. Water, even clean-looking tap water, is not sterile and harbors a variety of microorganisms that can adhere to the lens surface and be introduced into the eye. This risk applies to all water sources, including pools, lakes, rivers, and oceans, as well as domestic water supplies.
The most serious threat is the microscopic organism Acanthamoeba, which is commonly found in water and soil. If this amoeba contaminates a contact lens, it can cause a rare but devastating infection called Acanthamoeba keratitis (AK). AK is an infection of the cornea which is extremely difficult to treat and can result in severe pain, permanent vision loss, or even blindness.
Wearing lenses while showering increases the odds of developing AK by more than three times, underscoring the high-risk nature of even brief water exposure. For water activities like swimming, the only safe approach is to remove the lenses entirely or wear tightly sealed, prescription goggles and dispose of the lenses immediately afterward.
Restrictions on Wear Time and Sleep
A major prohibition is wearing contact lenses beyond the maximum recommended daily time or sleeping in them, unless specifically prescribed for extended wear by an eye care professional. The cornea, which is the only tissue in the body that receives oxygen directly from the air, needs a continuous supply to remain healthy. Contact lenses create a physical barrier that restricts this oxygen flow, a condition known as hypoxia.
When the eyelids close during sleep, the oxygen supply to the cornea is dramatically reduced, multiplying the hypoxic effect. This oxygen deprivation causes the cornea to swell and become more vulnerable to injury and infection, increasing the risk of a vision-threatening infection by up to eight to ten times. Over time, chronic hypoxia can trigger a condition called neovascularization, where the eye attempts to compensate by growing new blood vessels into the normally clear cornea.
This growth of blood vessels is a permanent complication. Therefore, daily wear lenses should typically be worn for no more than 16 hours a day, and napping, even for a short time, should be avoided with non-extended wear lenses. Following the replacement schedule is also non-negotiable, as overwearing disposable lenses allows protein deposits and bacteria to accumulate, promoting irritation and infection.
Forbidden Handling and Hygiene Practices
You must never reuse or “top off” the solution in your lens case; the old solution contains accumulated debris and pathogens, and adding new solution to it only dilutes the disinfectant, essentially letting your lenses marinate in a contaminated liquid. The solution must be completely discarded and replaced with fresh, sterile contact lens solution every time the lenses are stored.
Never use tap water, saliva, or homemade saline solutions to rinse, clean, or store your lenses. Saliva contains a high concentration of bacteria from the mouth that can cause severe eye infections, while tap water, even when purified, is not sterile and can introduce the dangerous Acanthamoeba organism. Similarly, using expired contact lens solution is prohibited, as the disinfecting agents lose their effectiveness over time, failing to properly sanitize the lenses.
Before touching your lenses, you must always wash your hands thoroughly with soap and water, and then dry them completely with a lint-free towel. Furthermore, never share your contact lenses, even decorative or colored ones, as this is a direct way to transmit bacteria and infections between individuals.
When to Immediately Discontinue Use
If you experience any of several specific symptoms, you must immediately remove your contact lenses and stop wearing them. The appearance of severe eye pain, intense redness that does not quickly subside, or a persistent foreign body sensation are all urgent warning signs. These symptoms can indicate a serious issue such as a corneal abrasion, severe inflammation, or a rapidly progressing microbial infection like bacterial keratitis.
Other mandatory signs for immediate removal include sudden blurred vision, excessive tearing, or any noticeable discharge or pus. If you notice physical damage to the lens, such as a tear, scratch, or bend, you must discard it at once, as a damaged lens can scratch the corneal surface. Once these symptoms appear, you must not attempt to self-treat; you must remove the lenses and immediately consult an eye care professional.