Contact Lens Hygiene: 12 Mistakes to Avoid for Healthy Eyes

Contact lenses are safe for the vast majority of people who wear them correctly. They offer freedom from glasses for sport, work and everyday life, and modern materials let plenty of oxygen reach the eye. But a contact lens sits directly on the cornea, the clear window at the front of the eye, and anything that contaminates the lens or deprives the cornea of oxygen can lead to problems ranging from irritation to a sight-threatening infection.

Health authorities such as the US Centers for Disease Control and Prevention (CDC) have reported that a large proportion of contact lens wearers admit to at least one risky hygiene habit, and that many serious infections are linked to behaviours that could have been avoided. The good news is that a few consistent habits dramatically reduce the risk. Here are the 12 most common mistakes and what to do instead.

Why hygiene matters so much

The cornea has no blood vessels; it gets most of its oxygen directly from the air. A lens reduces the oxygen supply to some degree, and the space between lens and eye is a warm, moist environment. If microorganisms reach this space, for example from fingers, water or a dirty case, they can stick to the lens and attack the corneal surface, especially if it has tiny abrasions from overwear or dryness.

The most feared complication is microbial keratitis, an infection of the cornea that can cause a corneal ulcer. Bacteria such as Pseudomonas are common causes; fungi and the amoeba Acanthamoeba are rarer but can be especially difficult to treat. Even with prompt treatment, keratitis can leave a scar that permanently reduces vision.

Mistake 1: Sleeping in your lenses

Sleeping in lenses, including short naps, is consistently identified as one of the strongest risk factors for microbial keratitis. With the eye closed, less oxygen reaches the cornea, and the lens stays in contact with the same tear film and microorganisms for hours. Research has shown that overnight wear increases the risk of keratitis several-fold compared with daily wear.

Some lenses are approved for extended or continuous wear, but even with these the risk of infection is higher than with daily wear, and the decision should be made with your eye care professional. If you fall asleep in daily-wear lenses by accident, remove them as soon as you wake, let your eyes rest, and watch for warning signs.

Mistake 2: Letting lenses touch water

Tap water, bottled water, swimming pools, hot tubs, lakes and the sea are not sterile. They can contain Acanthamoeba, a microscopic amoeba that can bind to soft lenses and cause a painful, hard-to-treat infection. Acanthamoeba keratitis is rare, but contact lens wearers account for most cases, and water exposure is a leading risk factor.

• Never rinse or store lenses or cases in tap water.
• Do not shower while wearing lenses if you can avoid it, and keep your eyes closed if you do.
• Do not swim in lenses. If you must, wear tight-fitting goggles and consider daily disposables that you discard immediately afterwards. Better still, use prescription goggles. See our article on swimming and your eyes.
• Dry your hands thoroughly after washing before handling lenses.

Mistake 3: Topping off solution

Topping off means adding fresh solution to the old solution already in the case. The disinfecting power of old solution has been used up, and microorganisms can multiply in it. Always empty the case completely, rinse it with fresh solution (never water), and fill it with new solution every time you store your lenses.

Mistake 4: Not replacing your lens case

Lens cases are a common source of contamination, because bacteria can form a sticky layer called biofilm that protects them from disinfectants. Clean your case every day by rubbing and rinsing it with fresh solution, leave it to air dry upside down with the caps off, and replace it at least every three months, or with every new bottle of solution if your manufacturer recommends this.

Mistake 5: Overwearing lenses

Wearing lenses for too many hours a day, or beyond their replacement date, deprives the cornea of oxygen and allows deposits to build up on the lens surface. Two-week lenses worn for a month, or monthly lenses stretched to three months, are a common problem. Follow the schedule for your lens type:

Also respect your daily wearing time. If your eyes feel dry or uncomfortable by evening, take your lenses out and switch to glasses. Our contact lenses guide explains the different lens types.

Mistake 6: Handling lenses with unwashed hands

Fingers carry microorganisms, cosmetics and oils. Wash your hands with soap and water, rinse well and dry them with a clean, lint-free towel before touching your lenses or eyes. Avoid moisturising soaps that can leave a film on the lens.

Mistake 7: Using the wrong solution, or saliva

Use only the solution your eye care professional recommends, and do not switch brands without asking, because different systems work in different ways. Saline is for rinsing only and does not disinfect. Never put lenses in your mouth to wet them: saliva is full of bacteria. Hydrogen peroxide systems must be neutralised before the lenses go in your eyes, using the special case supplied; putting unneutralised peroxide in the eye causes severe pain.

Mistake 8: Skipping the rub step

Many multipurpose solutions work best when you rub each lens gently with a fingertip for a few seconds and then rinse it, even if the bottle says no rub. Rubbing removes deposits and microorganisms more effectively than soaking alone. Ask your practitioner what is recommended for your solution.

Mistake 9: Wearing lenses when your eyes are red or irritated

If your eyes become red, painful or unusually sensitive to light, remove your lenses straight away and do not put them back in until the cause is known. Wearing lenses over a minor problem can turn it into a serious one. This also applies during episodes of conjunctivitis or allergies.

Mistake 10: Buying decorative or cosmetic lenses without a fitting

Coloured, costume or circle lenses sold online, at markets or in beauty shops are medical devices, even if they have no corrective power. When they are bought without an eye examination, they may not fit the eye properly, may be made of materials that let little oxygen through, and come without hygiene instructions. Cases of corneal ulcers and permanent vision loss linked to decorative lenses have been reported by organisations such as the AAO and FDA. If you want coloured lenses, get them fitted and supplied by a qualified eye care professional, and follow the same hygiene rules as for any lens.

Mistake 11: Ignoring makeup and personal care products

Put your lenses in before applying makeup and take them out before removing it. Avoid glittery or loose powders and lash-lengthening mascaras with fibres, which can get trapped under the lens. Keep hairspray and perfume away from your eyes while wearing lenses. Our article on eye makeup safety has more advice.

Mistake 12: Skipping eye examinations

Many problems with contact lenses develop silently, such as new blood vessels growing into the cornea from long-term oxygen shortage, or changes in your prescription. Regular aftercare checks, usually once a year or as advised, allow your practitioner to examine the health of your cornea, check the fit and update your lenses. Always keep an up-to-date pair of glasses so you can give your eyes a break.

A simple daily routine

1. Wash and dry your hands thoroughly.
2. Remove one lens, rub it gently with fresh solution if your system requires it, and rinse.
3. Place it in a clean case filled with fresh solution. Repeat for the other eye.
4. Leave the lenses to disinfect for the full time stated on the solution.
5. In the morning, insert the lenses, empty the case, rinse it with solution, and leave it to air dry face down.
6. Track replacement dates using a calendar or phone reminder.

Dry eyes and contact lenses

Dryness is the most common reason people stop wearing contact lenses. Screen work, air conditioning and reduced blinking all make it worse. Lubricating drops labelled as compatible with contact lenses can help, and your practitioner may suggest a different lens material or replacement schedule. See our guide to dry eye disease for more strategies.

When to see a doctor

Remember the warning signs that need prompt action. If you wear contact lenses and develop any of the following, remove the lenses immediately and seek same-day assessment from an eye doctor or emergency eye service:

• Eye pain, especially if it is getting worse or feels deep rather than scratchy.
• Redness that does not settle within an hour or so of removing the lens.
• Sensitivity to light.
• Blurred or reduced vision.
• Discharge, watering or a white or grey spot on the cornea.
• A feeling that something is stuck in the eye that does not go away after lens removal.

Take your lenses and case with you in a clean container, as they can help identify the cause of an infection. Do not use leftover antibiotic or steroid drops without medical advice. With early treatment, most contact lens complications can be treated successfully; with a few good habits, most can be avoided altogether.