Why Contact Lenses and Water Should Never Meet

Of all the rules in contact lens care, one matters far more than the rest, and it is the one broken most often because it seems excessive.

Lenses and water should never meet. Not tap water, not bottled water, not the shower, not the pool, not the hot tub, not a quick rinse of the case under the tap.

The organism

Acanthamoeba is a single celled organism that lives in soil and in water, including municipal water supplies. It is genuinely everywhere and, for the overwhelming majority of people, entirely harmless. It gets into your eyes in the shower every day and nothing happens.

What changes the situation is a contact lens. The lens provides two things acanthamoeba needs: a surface to attach to, and a way to be held against the cornea for hours. A minor corneal disruption, of the kind lens wear can cause, then gives it a route in.

Why it is so serious

Acanthamoeba keratitis is rare. It is also one of the conditions eye care most wants to avoid, for several reasons at once.

• It is extremely painful, characteristically out of proportion to how the eye looks
• It is frequently misdiagnosed early as a viral or bacterial infection, which delays correct treatment
• The organism forms a cyst, a dormant protected state that resists most treatment
• Treatment takes months of intensive drops rather than days
• It can result in permanent scarring and vision loss, and in severe cases in transplant

The disproportionate pain is worth remembering. An eye that hurts far more than it looks like it should is a specific warning sign and warrants urgent assessment.

Where the water actually comes from

Most people who develop this were not swimming in lenses. The exposures are more mundane.

Showering in lenses

Extremely common and rarely thought about. Water hits the face, runs into the eyes and sits against the lens. It happens every day for a lot of people.

Rinsing the case under the tap

Feels sensible and is not. Rinse cases with contact lens solution and let them air dry face down. Water introduces the organism to the exact environment where your lenses sit overnight.

Topping up old solution

Adding fresh solution to what is already in the case dilutes the disinfectant and leaves whatever was already growing. Empty it, rinse with solution, air dry, refill.

Swimming and hot tubs

Chlorine does not reliably kill acanthamoeba, and hot tubs are a particularly favourable environment for it. Neither is safe in lenses.

The case is the weak point

Cases develop biofilm, a layer of microorganisms bound in a protective matrix that solution cannot penetrate effectively. Once biofilm establishes, the case reinfects clean lenses every night.

Replace your case every three months at the latest, and more often if you notice any film or discolouration. It is the cheapest risk reduction available in the whole of lens wear.

The complete list

1. Wash hands with soap and dry them on a lint free towel before touching lenses
2. Never let lenses touch water of any kind
3. Empty the case, rinse it with solution, air dry it face down
4. Use fresh solution every time, never topping up
5. Replace the case every three months
6. Respect the replacement schedule for your lenses
7. Never sleep in lenses unless they are specifically prescribed for it
8. Never wear a lens in an eye that hurts, is red, or is sensitive to light

What to do about swimming

For occasional swimming, the answer is simple: take the lenses out, and use prescription goggles if you need to see.

For anyone who swims regularly, particularly children in swim programmes and competitive swimmers, Ortho-K is worth considering seriously. Correction happens overnight, so there is nothing in the eye during the day at all, and the water question disappears entirely.

Why dailies reduce the risk

A daily disposable lens is worn once and thrown away. There is no case, no solution and no storage, which removes most of the pathway by which contamination occurs.

That does not make water contact safe. A daily lens worn in the shower still traps organisms against the cornea. But for the routine, cumulative risk of lens care, dailies remove a great deal of it.

What an infection actually looks like

Knowing the presentation matters, because the difference between a good and a poor outcome is usually measured in days.

• Pain out of proportion to appearance. The classic acanthamoeba sign. The eye looks moderately red and hurts far more than it looks like it should.
• A white or grey spot on the cornea. Visible in a mirror in good light. This is an infiltrate or an ulcer and it needs seeing the same day.
• Light sensitivity that is severe rather than mild. Being unable to tolerate normal room lighting.
• Vision that does not clear on removing the lens. Blur that persists after removal is different from lens related blur.
• Discharge, watering, and a sensation that something is embedded in the eye that does not shift.

Any of these means remove the lenses, keep them in the case in case they are needed for culture, and contact the office. Do not put them back in, and do not wait to see whether it settles overnight.

The solution aisle, explained

Lens care products are poorly labelled for what they actually do, and the differences matter.

• Multipurpose solution. Cleans, rinses and disinfects. Convenient, adequate for most wearers, and the disinfection is less aggressive than peroxide.
• Hydrogen peroxide systems. More effective disinfection, including against organisms multipurpose solutions handle poorly. Must be fully neutralised in the special case for the full time stated. Peroxide in the eye is genuinely painful and entirely avoidable by not rushing.
• Saline. Rinses only. Does not disinfect anything. Storing lenses in saline overnight is the same as storing them in nothing.
• Daily cleaners and protein removers. Additional steps for specific deposit problems, usually with rigid lenses.

Never mix systems, never top up, and never decant solution into a smaller bottle for travel, which contaminates it.

If you have been doing it wrong

Most lens wearers have showered in their lenses. Many have rinsed a case under the tap. A fair number have topped up solution rather than replacing it.

Nothing about that requires guilt, and it does not mean anything is wrong with your eyes now. The risk is per exposure and low, which is exactly why the habits persist for years without consequence.

The useful response is to change the habits going forward and to have an examination if it has been more than a year, so corneal health is actually looked at rather than assumed. Blood vessel growth at the corneal edge, corneal thinning and early surface changes are all findable and all reversible when caught.

A note for parents

Children and teenagers are more likely to break these rules and less likely to report symptoms, partly from not wanting lenses taken away.

Daily disposables remove most of the risk by removing the routine. There is no case to contaminate, no solution to top up and no lens worn past its date. For a teenager, that is a considerably more robust system than good intentions.

Travel, where the rules get broken most

Almost every lens wearer who has run into trouble was travelling when it happened, and the reasons are consistent.

• Running out of solution somewhere it is hard to buy, and improvising. Take more than you need and keep it in hand luggage.
• Hotel bathrooms, where rinsing a case under the tap feels natural and the local water supply is unfamiliar.
• Swimming, which is what people travel to do, in pools and open water with higher organism loads than at home.
• Sleeping in lenses on a long flight, in an environment with very low humidity that dries the lens against the cornea.
• Not having a backup pair of glasses, which turns a minor problem into a ruined trip.

The straightforward answer for travel is daily disposables for the trip even if you normally wear monthlies. No case, no solution, no storage, and losing one costs nothing. Take glasses as well.