Earlier this week we spoke with Nicole Carnt (Scientia Associate Professor, Acting Clinical Teaching Director and Deputy Director of Research at the School of Optometry and Vision Science/Faculty of Medicine and Health at the University of NSW) to learn more about Acanthamoeba Keratitis (AK), a serious eye infection caused by a free-living amoeba found in water and soil.
Primarily affecting the cornea, the clear front part of the eye, Acanthamoeba Keratitis can lead to severe pain, vision loss and, in some cases, permanent damage or blindness.
With summer weather and pool party season just around the corner, we asked A/Prof Carnt what Aussies should know about this type of eye infection.
How common is Acanthamoeba Keratitis and who is most at risk?
Acanthamoeba Keratitis, while not extremely common, has been increasing in incidence, especially among certain groups. Individuals who wear contact lenses, particularly soft lenses, are at the highest risk.
Poor hygiene practices, such as not cleaning lenses properly, wearing them while swimming and showering, or using tap water for lens care, significantly increase the risk.
Farmers can also be at risk for AK, primarily due to their exposure to soil and water.
What are the common symptoms of AK and how can someone tell if they might have it?
Common symptoms of AK can vary in severity but typically include:
- Noticeable redness of the eye or surrounding area
- Intense eye pain that can be out of proportion to the visible signs
- Difficulty seeing clearly, which may worsen over time
- Increased sensitivity to light (photophobia)
- Excessive tearing or discharge from the eye
- A feeling of something being stuck in the eye
If you are experiencing any combination of these symptoms, especially if you are a contact lens wearer or have had exposure to potentially contaminated water or soil, it’s crucial to seek medical attention promptly.
What steps can contact lens wearers take to lower their risk of AK? Are there any specific cleaning routines or habits you recommend?
Contact lens wearers can take several important steps to lower their risk of Acanthamoeba Keratitis:
- Always wash and dry your hands thoroughly before handling contact lenses
- Only use disinfecting solutions recommended for contact lenses; avoid using water
- Adhere to the care instructions provided by your eye care professional or lens manufacturer
- Stick to the recommended schedule for replacing lenses, whether daily, weekly, or monthly
- Take out contact lenses before swimming, showering, or using hot tubs
- Never rinse lenses or lens cases with tap water; always use the appropriate solution.
What treatment options are available for AK, and how effective are they?
Treatment options for Acanthamoeba Keratitis primarily focus on controlling the infection and alleviating symptoms.
There is only one licensed treatment for Acanthamoeba Keratitis, Akantior, 0.08% PHMB drops and it is not available in most countries including Australia.
Therefore, drops need to be compounded by specialist pharmacies and have short use by dates. The dosage is hourly per day and night for several days and then tapered. Treatment can last months and even years.
Around 30% of cases develop painful scleritis which is treated with topical and systemic steroids. Incalcitrant cases can require an anti-leishmania drug called miltefosine which has troubling side effects such as nausea and hallucinations.
Further treatment can include cryotherapy, rose bengal photodynamic therapy, corneal transplantation, amniotic membrane transplantation, conjunctival flap and in some cases eye removal.
Side effects include glaucoma, cataract and fixed dilated pupils.
Because Acanthamoeba organisms can transform into a resilient cyst that is more difficult to treat, risk of recurrence is high.
Is there a risk of long-term vision loss from Acanthamoeba Keratitis?
Yes, there is a significant risk of long-term vision loss from Acanthamoeba Keratitis especially if the infection is not diagnosed and treated promptly (50-80% of cases are misdiagnosed as Herpes Simplex keratitis delaying antiamoebic treatments).
Steroids that are used to control inflammation in Herpes Stromal Keratitis, cause excystment and proliferation of Acanthamoeba organisms, which exacerbates the infection during misdiagnosis.
What is the role of The Global Alliance Against Acanthamoeba Keratitis?
The Global Alliance Against Acanthamoeba Keratitis plays a crucial role in raising awareness, promoting research, and advocating for prevention strategies related to Acanthamoeba Keratitis.
It is a collaboration of over 30 patients, clinicians, researchers, industry, regulators and charities.
For more information about Acanthamoeba Keratitis, please visit akeyefoundation.com/global-alliance-against-ak/
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