Swimming in Contact Lenses: What You Need to Know About Acanthamoeba Keratitis

A practical guide to contact lenses and water, the symptoms to watch for, and simple steps to help protect your eyes.

When the weather is warm, the idea of wild swimming in lakes, rivers or the sea can be especially appealing. But if you wear contact lenses, there is an important eye-health risk to be aware of before getting into the water.

Swimming in contact lenses can increase the risk of a rare but potentially serious eye infection called Acanthamoeba keratitis (AK). The infection is associated with a microbe called Acanthamoeba, which can be present in water. Understanding the risk – and knowing the symptoms to look out for – can help contact lens wearers make safer choices around water.

What is Acanthamoeba keratitis?

Acanthamoeba keratitis, often shortened to AK, is a rare eye infection that can occur when the eyes come into contact with water containing the Acanthamoeba microbe. Untreated water, such as lakes, rivers and the sea, is a particular concern. It is also possible to develop AK following exposure to chlorinated swimming-pool water or tap water, although this is less likely.

Why is swimming in contact lenses a risk?

Swimming in contact lenses is the major risk factor, accounting for more than 85% of cases. Contact lenses – particularly soft lenses – and contact lens storage cases can also become contaminated if they come into contact with tap water.

The risk can also be higher if the surface of the eye has been affected by a corneal abrasion or a foreign-body injury, even where the injury seems mild.

Can you swim with contact lenses?

The clearest advice is simple: do not swim in contact lenses, especially in untreated water. If you are around water, it is also important not to handle contact lenses that you intend to wear again with wet or dirty hands.

Avoid opening your eyes under water, and wear well-fitted swimming goggles to provide a measure of protection. The advice remains not to swim in contact lenses.

How to reduce the risk when wearing contact lenses

• Do not swim in contact lenses – particularly in lakes, rivers, the sea or other untreated water.
• Keep contact lenses and storage cases away from tap water to reduce the risk of contamination.
• Do not handle lenses with wet or dirty hands if you plan to wear those lenses again.
• Do not open your eyes under water and consider well-fitted swimming goggles as a protective measure.
• Act quickly if you are concerned by stopping contact lens wear and seeking medical advice promptly.

What are the symptoms of Acanthamoeba keratitis?

AK can take several days to develop, and the early symptoms can resemble those of other eye infections. Symptoms can include:

• Eye pain
• Redness of the eye
• Sensitivity to light
• Watery eyes
• A drop or reduction in vision

When should you seek advice?

If you are concerned about your eyes after water exposure – particularly if you develop pain, redness, light sensitivity, watering or a change in vision – do not continue wearing your contact lenses and seek medical advice quickly.

Further information

For more information about Acanthamoeba keratitis, visit Moorfields Eye Hospital.

Nic Sproson

Optometrist and Contact Lens Specialist

Please note: This article provides general information only. If you are concerned about your eyes or vision, seek appropriate medical or professional eye-care advice.