[2] Acanthamoeba are protozoa found nearly ubiquitously in soil and water and can cause infections of the skin, eyes, and central nervous system.

[12] As the disease progresses, it may penetrate through the cornea but very rarely causes infection inside the eye (endophthalmitis) due to a robust neutrophil response in the anterior chamber.

[15][16] In non-contact lens users, the greatest risks for developing Acanthamoeba infection are trauma and exposure to contaminated water.

[17] Further predisposing factors include contaminated home water supply, and low socioeconomic status.

These trophozoites are relatively ubiquitous and can live in, but are not restricted to, tap water, freshwater lakes, rivers and soil.

[18] In addition to the trophozoite stage, the organism can also form a double-walled cyst which may also be present in the environment, and can be very difficult to eradicate through medical treatment.

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.

To culture Acanthamoeba, scrapings are placed on a non-nutrient agar saline plate seeded with a gram-negative bacteria such as E. coli.

Polymerase chain reaction (PCR) can be used to confirm a diagnosis of Acanthamoeba keratitis, especially when contact lenses are not involved.

[22] Confocal microscopy is a non-invasive technique that allows visualization of Acanthamoeba in vivo in cases in which corneal scraping, culture, and cytology do not yield a diagnosis.

Medical therapy aims to eradicate both trophozoite and cystic forms of Acanthamoeba and also control the inflammatory response.

[citation needed] Multiple classes of drugs have been found to be effective in killing the trophozoite form of Acanthamoeba, including anti-bacterial, anti-fungal, anti-protozoal, and anti-neoplastic agents.

[12][24] Due to the efficacy of these drugs against the Acanthamoeba, as well as their low toxicity to the cornea, they are commonly used as the first line medications in the treatment of AK.

[26][27][28] Due to the potential for negative longterm visual outcomes with AK, therapy is usually started with a combination of a biguanide and a diamidine.

If an appropriate response to therapy, this may be reduced to hourly administrations during the day only, which is continued for several weeks to months.

While surgery is capable of restoring vision by replacing a damaged cornea, it also carries risks of recurrent Acanthamoeba infection or graft failure.

The data showed that 89% of the infected patients were contact lens wearers, almost all cases occurred only in one eye, and 19% required a corneal transplant.