Acanthamoeba keratitis

Acanthamoeba keratitis is an infection of the cornea caused by Acanthamoeba, a microscopic organism found in water, soil and the air. The condition is rare, but can be serious and requires prompt medical attention.

The organism is found in tap water, swimming pools, hot tubs and lakes. In contact lens wearers, the infection usually occurs when lenses come into contact with contaminated water, or when lenses are cleaned with tap water instead of the prescribed lens solution.

How does the infection develop?

Acanthamoeba can penetrate the cornea, particularly where there is minor damage or irritation. This occurs more frequently in contact lens wearers because:

• Lenses are rinsed or stored in tap water
• Lenses should not be worn whilst swimming or showering
• The lens case is not replaced regularly
• Failure to wash hands properly before inserting lenses
• Lenses are worn for longer than recommended

Characteristics and symptoms

The initial symptoms may resemble other, less serious eye conditions. Typical symptoms include:

• Pain that is out of proportion to the visible redness
• The sensation of having something in your eye
• Excessive tear production
• Light sensitivity
• Blurred or impaired vision
• Redness of the eye

Symptoms often develop gradually over a period of days to weeks. As the symptoms are not always specific, the diagnosis is sometimes made late.

Diagnosis and progression

An ophthalmologist makes the diagnosis through microscopic examination of the cornea and, in some cases, by means of a culture or biopsy. Early detection is important, as the infection is difficult to treat and can lead to permanent damage to the cornea and vision.

Risk factors associated with contact lenses

Contact lens wearers are at increased risk of Acanthamoeba keratitis, particularly when hygiene guidelines are not followed. The organism easily attaches itself to contact lenses and lens cases, where it can survive and multiply.

Most cases of Acanthamoeba keratitis in contact lens wearers can be traced back to contact with water. Tap water is not sterile and may contain Acanthamoeba, even if it meets drinking water standards.

When to see an optician

If you experience any of the following symptoms, contact your optician immediately:

• Eye pain that persists or gets worse
• Redness that does not go away after removing your lenses
• Increasing sensitivity to light
• Blurred vision that does not improve
• The sensation of having something in your eye, even without a lens

Always mention that you wear contact lenses and whether your lenses have come into contact with water. Early diagnosis and treatment are important for minimising permanent damage.

Treatment and recovery

Treatment for Acanthamoeba keratitis is carried out by an ophthalmologist and involves special eye drops that often need to be used for several months. The treatment is intensive and requires strict adherence to the prescription.

Recovery can take a long time and depends on how early the infection is detected and how severe the damage to the cornea is. In some cases, a corneal transplant is required.

Reducing the risk

Although Acanthamoeba keratitis is rare, there are clear guidelines that can help reduce the risk:

• Clean lenses only with the prescribed lens solution; never use tap water
• Rinse the lens case with lens solution after use and leave it open to dry
• Replace your lens case regularly, in accordance with the instructions for use
• Wash your hands thoroughly and dry them before touching your lenses
• Do not wear contact lenses whilst swimming, showering or in a hot tub
• Do not wear lenses for longer than recommended
• Do not use lens solution after the expiry date

These measures are intended to reduce the risk of infection, but cannot rule out the possibility of infection entirely. If you have any symptoms or are unsure, please have them assessed by your optician, optometrist or ophthalmologist.