Are colored contact lenses bad for your eyes? When they are safe, and how to buy and wear them safely

Colored contact lenses are not bad for your eyes in themselves, but they are a medical device that sits on the cornea like corrective lenses, and most harm comes from three mistakes: buying without an exam and prescription, buying from an unlicensed seller, or misuse such as sharing them or sleeping in them. The US Food and Drug Administration says decorative lenses are not cosmetics and every contact lens must be prescribed by a doctor, even with perfect vision. The Saudi Food and Drug Authority advises against buying lenses from unlicensed places or wearing someone else's. Get your eyes examined, buy from a licensed seller who asks for the prescription, and remove the lens and see an eye doctor right away at any redness, pain or blurred vision. Daily cleaning steps are in our guide to safe contact lens use.

Why a colored lens is treated as a medical device, not makeup

Many people see a colored lens as mere decoration because it usually has no prescription power, but the eye cannot tell a lens that corrects vision from one that changes its color: both rest on the cornea for every hour they are worn. That is why the US Food and Drug Administration says decorative lenses are not one size fits all, and that an eye doctor (an ophthalmologist or optometrist) must measure each eye to fit the lens properly. A lens that does not fit your eye can scratch the surface of the cornea or stick to it. The American Academy of Ophthalmology adds another reason: the paints and pigments make a colored lens thicker and less breathable, so less oxygen may reach the eye. The Academy describes the case of a woman who bought colored lenses at a souvenir shop, felt extreme pain in both eyes just 10 hours after first putting them in, could not see well enough to drive for 8 weeks, and was left with a scar on her cornea.

What harm unprescribed colored lenses can do

The US Food and Drug Administration says an ill-fitting colored lens can cause a scratch on the cornea, an infection of the cornea or conjunctivitis, decreased vision, and even blindness. It warns that bacterial infections can develop extremely fast, cause corneal ulcers, and sometimes lead to blindness within as little as 24 hours if not diagnosed and treated promptly. The numbers come from the American Academy of Ophthalmology, which reports the findings of several studies:

• Infection risk: the Academy reports a 2011 study in which people who wore colored lenses were 16 times more likely to develop keratitis, an infection of the cornea, than people who wore regular contact lenses.
• Contamination: the US Food and Drug Administration tested more than 300 cosmetic lenses and found microbial contamination in 60% of the counterfeit lenses and 27% of the unapproved ones.
• The pigment itself: a 2015 Japanese study found chlorine in 3 types of colored lenses sold without a prescription and iron on 4 pairs, and the printed patterns on some lenses leave an uneven surface that could scratch the eye.
• Long-term complications: a scratch can turn into a corneal ulcer, an ulcer can heal with a scar that permanently reduces vision, and in severe cases the patient may need a corneal transplant.

Where to buy colored lenses safely: a checklist before you pay

The US Food and Drug Administration advises never buying lenses from street vendors, salons or beauty supply stores, boutiques and novelty stores, flea markets, convenience stores and beach shops, or websites that do not ask for a prescription, and it says selling them without a prescription breaks the law in the United States. In Saudi Arabia, the Saudi Food and Drug Authority advises against buying contact lenses from unlicensed places, and it ran an awareness campaign called “For Your Eyes” that displayed samples of non-conforming and counterfeit lenses and glasses. Before you pay, check these points:

• An eye exam with a specialist, even if your vision is perfect and you only want the lens for the color, because the fit decides whether the lens will sit on your eye safely.
• A valid prescription that states the lens brand, its measurements and the date the prescription expires, as the American Academy of Ophthalmology recommends.
• A licensed seller who asks for your prescription before selling. A seller who never asks has no way of knowing whether the lens fits your eye.
• A sealed, intact package with a visible expiry date, and steer clear of any advert claiming the lens is “one size fits all” or that you “don't need a doctor”.

Wearing rules that prevent most problems

Buying correctly is half of safety; the other half is how you use the lenses. These are the key guidelines from the Saudi Food and Drug Authority for contact lens wearers, and they apply to colored lenses just as they do to corrective ones:

• Do not wear another person's lenses or lend yours to anyone, even for a single occasion, because this can transmit disease or cause serious eye injuries that may lead to blindness. In a survey of 686 women in Texas, reported by the American Academy of Ophthalmology, 1 in 4 said they had used lenses without a prescription, about 60% of those wearers reported eye problems, and the rate rose to 88% among women who had borrowed someone else's lenses.
• Do not sleep in daily lenses, as they can cause eye irritation and infection.
• Do not rinse lenses with tap water, distilled water or any homemade solution, do not wet them with saliva, and do not swim while wearing them.
• Put lenses in before applying makeup and take them out before removing it, and use hairspray and perfume before putting them in, not after.
• Replace the lens on schedule and throw it away when its period ends, keep a backup pair of glasses, and remember that a lens does not protect you from the sun, so wear sunglasses over it.

When to take the lens out and see a doctor straight away

Any single one of these symptoms is enough to take the lens out immediately and see an eye doctor; they do not have to appear together: redness, eye pain that does not go away after a short time, excessive tearing, increased sensitivity to light, blurred or decreased vision, discharge, or swelling. This list combines what the US Food and Drug Administration and the American Academy of Ophthalmology describe, and the Saudi Food and Drug Authority likewise advises removing the lens immediately and consulting a doctor at any change in vision, redness or irritation. Do not put the lens back in, and do not wait until the next morning to see whether the pain eases, because a corneal infection can progress within hours. Do not reach for eye drops you have at home without asking the doctor, as the Authority advises consulting one before using any eye drops or solutions with contact lenses.