Acanthamoeba keratitis is a rare (Orphan Disease) infectious living organism that affects the cornea and is caused by a protozoa of the Acanthamoeba family, present in soil, air and water.
The vast majority of cases (about 85%) appears in contact lens wearers, due to improper use of lenses, such as: inadequate cleaning and storage, night and prolonged usage, etc. However, infection can occur even after corneal trauma, especially in rural areas.
It is a form of keratitis with a fairly low prevalence (7 cases per 1,000,000 in Europe), but that can have devastating effects on patients, as it can cause intense pain and, if not effectively treated, can lead to major deterioration of vision (even blindness) and corneal perforation.
The most common symptoms are pain, redness, blurred vision, sensitivity to light and excessive tearing. These are manifestations similar to those of other eye infections and may persist for several weeks.
The natural history of the disease is related to the specific characteristics of Acanthamoeba, whose life consists of one active and one infectious stage of "dormant cysts", during which the organism manages to survive adverse environmental conditions.
Early diagnosis is extremely important and certainly improves the outcome of the infection.
To eradicate Acanthamoeba keratitis, therapy must rely on medications that can suppress the protozoa in both phases of its life cycle (one active and one cystic) in order to completely eradicate the pathogen agent.
No drug licensed for the treatment of Acanthamoeba keratitis is currently available in any country. In recent years the administration of a combination (off label) of anti-amoebic agents such as biguanides and diamidin has greatly improved results. The use of biguanides in particular has revolutionised the course of the disease, especially if treated in the early stages, because pain relief is fast. To get a complete clinical resolution, however, therapy is extended for several months; clinical resolution through medical treatment alone is obtained in the majority of patients (approximately 75%), and in many cases it is necessary to perform a corneal transplant during the course of the disease.