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Acanthamoeba Keratitis

Sometimes a horror story appears in the media of bacteria eating the eye. This is acanthamoeba keratitis - a specific type of ulcer that forms on the cornea. It's a serious condition that can severely damage the eye quickly, but thankfully is comparatively rare. 85% of cases are caused via contact lens wear, and there are other organisms which can also cause unpleasant corneal ulcers. All need immediate treatment to prevent long term scarring.

Acanthamoeba, and many of the other ulcer causing organisms live in water. Via swimming pools, showers, tap water etc we come into contact with them, and it's when they infect the cornea that major problems occur. Contact lenses should never be worn if they could be exposed to water, or handled in bathrooms. Lenses and cases should be washed in specified solution.

Contact lenses are designed to work with the eyes, interacting with tears so they don't dry out, and allowing oxygen through. Therefore lens materials are absorbent, and if acanthamoeba gets into a lens on the eye it's in perfect growing conditions - light, warm, moist, and with available nutrients from your tears. As the lens on the cornea, it's easy for infection to take hold.

This is one of the reasons why patients are given specific wearing times for their lenses, so if you are told to dispose of your lenses after a month, it's because it cannot be guaranteed to stay free of bacteria after that time. When you dispose of your lenses dispose of the case and solutions too, to ensure you're using the most sterile products possible - even if you have some left!


Usually the symptoms of Acanthamoeba are severe and easily felt. There is often sudden pain and discomfort which worsens quickly, and if associated with contact lens wear discomfort intensifies when the lens is removed and the bacteria attack the dense network of nerves that fill the cornea. Often there is sensitivity to light, and the eye will become bloodshot and watery. These are all signals from the eye that there is something seriously wrong.

As it's a severe condition, if you experience these symptoms you should see an Optometrist immediately. The GP may be able to help, but most do not have the equipment to make a full diagnosis. There is a simple phrase to remember regarding contact lenses - if in doubt, keep them out! If you feel they're not quite right, remove the lenses and come in as soon as possible. Always keep up to date specs in case of such emergencies.

If diagnosed you will have to dispose of the current set of lenses, solutions and case. You will probably have to go to the hospital eye department for antibiotics. They will test the bacteria to confirm Acanthamoeba or anything else. if caught early it will heal without problems, but serious infections left untreated will scar the cornea permanently.

Regular check ups are essential as your vision may be stable but the way your eye interacts with your lenses may change. The lens may give good vision and feel fine, but may be causing unseen damage that leaves you more vulnerable to infections. This is why people are often discourged from buying lenses online, as they miss out on regular checks that ensure their eyes are still coping with their contact lenses.

Manish has gone the extra mile to help me and I really appreciate it.

A. W. Olney

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