Contact lenses can cause two major categories of complications: infections and damage to lubricating glands. Infected corneal ulcers which can cause scars that block central vision. Permanent damage to lubricating glands, can cause eyes to feel dry and uncomfortable, sometimes even when lenses are not being worn.
HOW TO AVOID INFECTION
Never sleep with contact lenses
The cornea ordinarily resists infection because the tears constantly flush away bacteria, and antibodies in the tears kill bacteria. A contact lens allows bacteria to accumulate beneath the lens because it prevents the tears from circulating freely across the corneal surface. Lenses fitted loosely enough to permit movement of the lens with each blink allow some tear circulation. Removing the lenses during sleep is critical. Tear circulation beneath a lens is even less while asleep than while awake. And removing the lens for many hours allows tears to flush adherent bacteria, and tear antibodies to kill those bacteria that won’t flush away. So, never sleep with contact lenses; even those that the FDA has approved for overnight wear. Sleeping with lenses increases many times over the risk of serious infection. Also, if a red, irritated eye does not feel better an hour after removing the lens, call your eye doctor.
Disinfect with hydrogen peroxide nightly
Most patients disinfect their lenses by storing in a multipurpose solution that is gentle enough to put into your eye. Such solutions are not only gentle on your eye, but gentle on bacteria. There is convincing research that multipurpose disinfection is associated with greater risk of infection than hydrogen peroxide disinfection. You can find hydrogen peroxide disinfection systems in the contact lens area of your pharmacy. The systems come with a special case that catalytically converts the hydrogen peroxide to water over about 5 hours. So anytime after 5 hours, you may place the lens directly into your eye. Another benefit: after catalytic conversion of the hydrogen peroxide, the solution contains only pure saline, without preservative. So eyes sensitive to even the mild preservatives in multipurpose solutions may be more comfortable with hydrogen peroxide disinfection.
Never swim with contact lenses
The risk is greatest in unchlorinated water like lakes and oceans. Amoebas in the water can cause a severe corneal infection which comes on very gradually over a few weeks. Treatments are fairly ineffective. If you do swim with a lens, discard it afterwards. Hydrogen peroxide will probably kill any amoebas, unless there is mucus on the lens surface protecting the amoebas from the disinfectant.
Wear lenses only about 8 hours a day
Research shows that wearing contact lenses for years gradually damages the Meibomian glands which secrete oils onto the cornea to prevent the tears from evaporating too quickly. Damaging the lubrication system of the eye can cause chronic redness and irritation which is not only uncomfortable, but unattractive. It may also prevent you from wearing lenses at all in the future. Since the risk of damage increases with the number of years of wearing time, it is likely that wearing contact lenses for fewer hours per day reduces the risk of lubrication gland damage. I advise wearing lenses for only about half of waking hours. This way you can hope to wear lenses successfully for many decades.