AK should be considered in all patients who use contact lenses, and following corneal abrasions or trauma. A thorough history should be obtained, especially relating to contact lens use and any recent changes contact in lens solution, exposure of the eyes to water or foreign objects, and symptoms that the patient is experiencing. The symptoms classically attributed to AK include decreased or blurred vision, sensitivity to light (photophobia), redness of the eye (conjunctival hyperemia), and pain out of proportion to physical exam findings. Another clinical feature that can distinguish Acanthamoeba from bacterial causes of keratitis is a lack of discharge from the eye.On physical exam, findings will depend on the stage of the disease. Early manifestations in the cornea can be seen as punctate keratopathy, pseudodendrites, and epithelial or subepithelial corneal deposits. These features can lead an examiner to confuse AK with a viral keratitis, such as that caused by varicella zoster virus or herpes simplex virus. As the disease progresses and infiltrates the corneal stroma, a classic "ring infiltrate" may be present on examination (although this is only seen in about 50% of cases). Corneal ulceration, or in severe cases, perforation, can also occur and may be accompanied by hypopyon.In cases of keratitis, diagnosis is typically achieved through evaluation of corneal scrapings. Scrapings are taking from the cornea, and plated on agar for culture, and also can be stained using Gram stain and Giemsa stain to differentiate between bacterial keratitis and AK.
Therefore it is typically recommended that steroids be used briefly to aid in symptom resolution, and that anti-amoebic agents be used both during, and for several weeks after topical steroid use. Surgical treatment
Surgical debridement of an infected cornea can also be used to reduce organism load and excise devitalized tissue from the cornea. It may also improve the efficacy of medical therapy by promoting penetration of medication into deeper layers of the cornea. In cases of corneal ulceration or perforation, or if corneal scarring is severe, corneal transplant may be required. This typically involves full thickness transplantation of the cornea from a healthy donor eye. The size of the graft should be kept as small as possible, as larger grafts carry a great risk of host rejection, and due to the possibility of graft revision surgery. While surgery is capable of restoring vision by replacing a damaged cornea, it also carries risks of recurrent Acanthamoeba infection or graft failure. For this reason, anti-amoebic medications should be started prior to surgery, and continued for several weeks afterward. If there is suspicion or evidence of recurrent infection, cultures should be sent. If cultures are positive, anti-amoebic therapy should be continued for 6 months.Outcomes following surgery are typically much better for patients who receive surgery for vision improvement following infection resolution, and therefore all efforts should be made to maximize medical management before attempting surgery. Epidemiology
A study in Austria reported a total of 154 cases of Acanthamoeba keratitis over a 20-year period.