Contact Lenses & Swimming

Whether you are diving into a hotel swimming pool on holiday, swimming laps at your local leisure centre, or relaxing in a outdoor hot tub, the temptation to leave your contact lenses in is understandable. After all, nobody wants to navigate the pool edge with blurry vision.

However, eye care professionals across the UK agree on one absolute rule: water and contact lenses should never mix. Combining contact lenses with swimming, showering, or water sports creates the ideal breeding ground for severe, sight-threatening eye infections.

Why Water and Contact Lenses Are a Dangerous Mix

Soft contact lenses act like tiny sponges on the surface of your eye. When exposed to water, they quickly absorb liquid alongside whatever micro-organisms, chemicals, and debris happen to be floating in it.

This causes three main problems:

1. Trapped Pathogens: Water gets trapped underneath the lens, holding bacteria, viruses, and parasites directly against your delicate cornea (the clear front surface of the eye).

2. Microscopic Trauma: Contact lenses can swell or change shape when exposed to non-sterile water, causing them to fit tightly against the eye. This friction creates microscopic scratches on the cornea, giving pathogens an easy entryway into deeper eye tissue.

3. Chemical Irritation: Chlorine and other pool sanitisers, while necessary for water hygiene, strip away the natural tear film that protects your eyes, leaving them vulnerable and inflamed.

Key Takeaway: Tap water, pool water, lakes, rivers, and sea water are never sterile. Even heavily chlorinated pools contain resilient micro-organisms that chlorine cannot kill immediately.

Acanthamoeba Keratitis: The Sight-Threatening Parasite

While water harbours various harmful microbes, the most dangerous threat to contact lens wearers is a microscopic single-celled organism called Acanthamoeba.

When this amoeba infects the cornea, it causes a rare but devastating condition known as Acanthamoeba keratitis (AK).

What is Acanthamoeba Keratitis?

Acanthamoeba are naturally occurring, free-living amoebae found in almost all water sources — including tap water, swimming pools, hot tubs, lakes, and oceans. Under normal circumstances, your eye's tear film sweeps these organisms away harmlessly. However, when a contact lens wearer swims or showers with lenses in:

• The amoeba attaches to the contact lens surface.

• It feeds on bacteria living on the lens.

• It penetrates the corneal surface through microscopic abrasions.

• Once inside, it burrows into the corneal tissue, causing severe inflammation and tissue damage.

Symptoms to Watch Out For

Acanthamoeba keratitis is notoriously difficult to diagnose in its early stages because its initial symptoms mirror common bacterial eye infections or simple contact lens irritation:

• Extreme pain out of proportion to the visible appearance of the eye

• Severe eye redness and watering

• Extreme sensitivity to light (photophobia)

• A sensation of having something stuck in your eye (foreign body sensation)

• Blurry vision or cloudiness over the cornea

The Long-Term Consequences

Because Acanthamoeba can form protective cysts when under stress, the infection is exceptionally resistant to standard antimicrobial treatments. Treatment often requires intensive antiseptic eye drops administered every hour — day and night — for weeks or even months.

In severe cases, Acanthamoeba keratitis can lead to permanent scarring, permanent vision loss, or the need for a corneal transplant (keratoplasty).

Other Infections Associated with Swimming in Lenses

While Acanthamoeba is the most feared pathogen, swimming with lenses exposes you to several other hazards:

Safer Alternatives for Swimmers Who Need Vision Correction

You do not have to compromise on safety to enjoy clear vision in the water. Eyecare experts recommend the following solutions:

1. Prescription Swimming Goggles (The Gold Standard)

Prescription goggles are custom-fitted with lenses matched to your optical prescription. They provide sharp vision underwater while keeping all water away from your eyes, eliminating infection risks entirely.

2. Daily Disposables Under Watertight Goggles (If You Must Wear Lenses)

If prescription goggles are not an option, the British Contact Lens Association (BCLA) advises:

• Wear daily disposable contact lenses.

• Cover them with tight-fitting, watertight swimming goggles.

• Remove and discard the lenses immediately after exiting the water.

• Wash and dry your hands thoroughly before touching your eyes or applying a fresh pair of lenses.

What to Do If Water Touches Your Contact Lenses

If you accidentally swim, shower, or get splashed in the face while wearing contact lenses, follow these steps immediately:

1. Remove Lenses Promptly: Take the lenses out as soon as possible with clean, dry hands.

2. Dispose or Disinfect: If using daily disposables, throw them away immediately. If using reusable lenses, thoroughly rub and rinse them with fresh, sterile contact lens disinfecting solution (never tap water!) and leave them in a clean case with fresh solution for at least 6 hours.

3. Monitor Your Eyes: Watch closely for signs of redness, irritation, discharge, pain, or light sensitivity over the following days.

4. Seek Immediate Medical Attention: If you experience eye pain, redness, or blurry vision after swimming with contact lenses, visit an optometrist, an eye casualty unit, or your local GP right away. Early diagnosis of conditions like Acanthamoeba keratitis is critical to saving your sight.