Acanthamoeba keratitis (AK)
Acanthamoeba keratitis is a rare but serious eye infection of the cornea (clear ‘window’ at the front of the eye) that is painful and becomes inflamed and sight-threatening.
The infection is caused by a microscopic organism called acanthamoeba, which is common in nature and is usually found in lakes, oceans, rivers and other bodies of water such as tap water, swimming pools, hot tubs, soil and air.
Information on Acanthamoeba keratitis
Causes
In the UK, AK is mostly common in people who wear contact lenses, but anyone with a corneal injury is susceptible to developing the infection. About 1 in 30,000 contact lens wearers become infected.
Using tap water to clean or store contact lenses or having poor contact lens hygiene increases the risk of infection. Examples of poor lens hygiene are not using disinfection solutions properly, reusing the solution in the contact lens case, failing to empty and dry the contact lens case after use and storing lenses in water overnight.
Wearing contact lenses when swimming or taking a shower also increases risk. So, does putting lenses in with wet hands from tap water.
Symptoms
Acanthamoeba keratitis is very painful for most people but it’s possible to have no pain at all. Other symptoms include red eyes that feel irritated or like they have something in them. Some people will get blurred or poor vision, while others may become sensitive to light and find it painful or uncomfortable.
If you ever experience any of these types of symptoms, you need to make sure to contact your eye doctor. Remember that acanthamoeba keratitis is sometimes difficult for your eye doctor to diagnose at first, because its symptoms are similar to pink eye symptoms and those of other eye infections.
Diagnosis of keratitis often occurs once it is determined that the condition is resistant to antibiotics used to manage other infections. A "ring-like" ulceration of your corneal tissue may also occur.
How is AK diagnosed?
An ophthalmologist will use a standard slit lamp microscope to look for signs of inflammation in your cornea, including specific clinical signs characteristic of AK. This is can be followed by a corneal scrape and culture, or a swab of the cornea to check for Acanthamoeba DNA using a test called “PCR”. Results for both these tests take a few days to come through. In some cases, AK can be detected using a confocal microscope, a powerful scanner that can see Acanthamoeba cysts within the various layers of the cornea. The ophthalmologist will use these tests together with other clinical signs and symptoms in order to decide on the appropriate treatment plan
Treatments
Acanthamoeba keratitis needs immediate attention. Treatment is usually with antiseptic eye drops. It can be hard to treat and may also need antibiotics or steroids as well as painkillers.
The most serious infections will mean the need for a corneal transplant. This involves surgery to remove the damaged cornea and replace it with a healthy one from a suitable donor. If needed, penetrating keratoplasty should only be used for cases of visually significant corneal scarring in quiet eyes. If there are still signs of active infection or even if there are cysts lingering in the cornea, then infection may recur in the graft.
Prevention
Good contact lens hygiene is imperative. This means, clean and dry your hands well before touching your lenses. Make sure you do not sleep with contacts lenses.
Follow the advice from your optician and the manufacturer’s instructions for your lenses. Consider options such as daily disposable lenses instead of ones that need to be cleaned and stored to use again. It is also important to clean, rinse and air-dry your contact lens case straight after removing your lenses from the case. Throw away the old solution and rub the inside wells of the case with clean fingers for a few seconds. Then fill the case with multipurpose solution or sterile saline and store the case upside down with the caps off.
Don’t wear contact lenses when you take a shower or indulge in activities where bodies are involved when you are wearing contact lenses.
This is just informative piece, please seek medical attention if you feel you have any of the symptoms.