Colored contact lenses for Halloween: what are the risks, and can you wear them after laser eye surgery?

Vampire eyes, white irises, red pupils: every year around Halloween, colored contact lenses make a comeback. You can find them online or in costume shops, sometimes for a few euros. And every year, patients who have had surgery ask me whether they are allowed to wear them for their party.

The answer is yes, with a few precautions. But to understand them, you first need to know what a lens, any lens, does to the cornea.

Myth: “They are fashion lenses with no correction, so they are safe.”

Whether it corrects vision or not, a lens sits on the cornea in the same way. It therefore has to fit your eye, exactly like a prescription lens.

What a lens does to the cornea

The cornea has no blood vessels, which is what makes it transparent. It gets much of its oxygen directly from the air, through the tear film. A lens sits in between, and depending on its material and thickness, it lets more or less oxygen through.

The surface of the cornea is covered by the epithelium, a thin layer of cells that protects it from germs. If the lens is too tight, it presses. If it is too loose, it moves and rubs. Either way, the epithelium gets damaged in places, often without you noticing, and germs find a way in.

That is why a prescription lens is chosen after an examination: the curvature of the cornea is measured, and the fitter checks that the lens is well centered and moves just the right amount. A lens bought for a party usually skips this step [4].

What sets colored lenses apart

In Europe, they are subject to the same regulation as medical devices [5]. The risk comes rather from how they are sold: most come in a single curvature and a single size, and nobody checks that they suit your eye.

How they are made matters too. Depending on the model, the pigment is sealed inside the lens or placed closer to its surface, which may then be slightly less smooth. And the colored layer can reduce oxygen flow, although this is not true of all of them [3]. That is not a reason to go without them, it is a reason to choose them carefully.

The risk to know about: infection of the cornea

When the epithelium is damaged, a germ can get into the cornea: a bacterium, a fungus, sometimes an amoeba. This is called infectious keratitis. First a white spot appears in the cornea, which can spread and form an abscess. Treatment clears the infection, but a scar often remains, and if it is central, vision can stay reduced for good.

A French study carried out in twelve university hospitals recorded 256 cases of keratitis in contact lens wearers. 32 of them, one in eight, involved decorative lenses [1]. This does not mean that one wearer in eight gets an infection: the study only looked at patients who were already infected. What it shows is who those patients were. Younger (21 on average), they had rarely bought their lenses from a professional, and most had never been told how to care for them. Their infections were also more severe: six in ten were left with vision worse than 20/200, compared with about one in eight among prescription lens wearers [1]. Another study by the same group found decorative lenses among the risk factors for infection, alongside sleeping in lenses and keeping the same disinfecting solution for too long [2].

What if you have had eye surgery?

Laser eye surgery does not rule out contact lenses, prescription or colored. What matters is that the cornea has fully healed.

After LASIK, the laser worked under a flap, a thin layer of cornea that is laid back at the end of the procedure. During the first weeks, anything that could irritate it is avoided. The eye is also often a little drier for a while, and a lens is then less well tolerated.

After TransPRK, the laser removes the epithelium, which grows back within a few days. A lens is placed at the end of the procedure, but it is a bandage lens: it protects the cornea while it heals and is removed at the check-up. It is not a comfort lens.

Before wearing lenses again, I wait at the very least until the epithelium has fully closed, which takes about three weeks, and I check at the follow-up visit that the eye surface is stable and that dryness has settled. For colored lenses, worn for fun, in practice I prefer to wait a few months. If your surgery is recent, let’s talk about it before the party (see also recovery after surgery).

You should also know that the cornea has changed shape. After myopia correction, it is flatter in the center, and a standard lens may sit poorly on it. Fitting a lens on an operated cornea sometimes takes a few more trials [6]. All the more reason to go through an optician, even for a lens with no correction.

If you had surgery a long time ago and everything is fine, your surgery is not a contraindication. The risks are the same as for everyone else: a poorly fitted lens and approximate hygiene.

If you wear them

• buy them from an optician, or online if they carry the CE mark, and mention your surgery if you have had one;
• wash and dry your hands, and never use tap water or saliva: amoebas found in water cause the most serious infections;
• do not share them and do not sleep in them, not even for a short nap;
• limit wear to the evening, and throw daily lenses away as soon as you take them out;
• do not use last year’s lenses.

Highly opaque lenses, white or black, also reduce your field of vision. Be careful walking in the street, and do not drive with them.

When to see a doctor

Mild discomfort that disappears when you remove the lens is common. If it persists, talk to an ophthalmologist. And see one the same day if you have pain that does not go away after removing the lens, a red eye, strong sensitivity to light, reduced vision or a white spot visible on the cornea.

In that case, do not use eye drops at random, and bring the lens and its case: they help identify the germ.

In summary

Yes, you can wear colored contact lenses after laser eye surgery, once the cornea has fully healed. As for everyone else, the risk depends mainly on the quality of the lens, how well it fits and how it is worn. And if you have any doubt before your party, ask me.