Abstract: In recent years, Acanthamoeba keratitis (AK) has became a clinically significant
problem because of the broad use of contact lenses that are the major risk factor of the disease.
AK can have a severe course leading to significant vision loss. It is caused by the Acanthamoeba
species of protozoa, potentially leading to permanent vision loss. AK requires prompt diagnosis
and treatment to preserve visual acuity. Severity is often associated with delayed diagnosis
and/or uncontrolled disease. The treatment presents considerable difficulties due to similarity
of clinical manifestations of AK to other keratites (bacterial, herpetic, and fungal), which often
leads to late diagnosis and formation of drug- resistant cysts. There is currently no specific
drug universally suitable for monotherapy of AK. Instead, 2 agents (usually chlorhexidine and
poligexametilen biguanide) are used that, if combined, are effective against both trophozoites
and cysts. If necessary (severe keratitis, insufficient treatment effect), diamidines (propamidine
and its analogs), antifungals (fluconazole, itrakonazol), certain antibiotics (Neomycinum), and
iodine-containing medications (povidone-iodine) can be prescribed. The use of corticosteroids
is considered unjustified because of the risk of rapid progression (due to disturbance of local
immunity and also provocation of excystation of the amoebas). The penetrative keratoplasty
may be required, especially if a descemetocele or corneal perforation occurs, however, its
results are generally worse than those in other keratites because of a higher risk of
complications (iridocyclitis, secondary glaucoma, AK recurrence in the graft). In some cases,
good results are achieved with minimally invasive surgeries, such as mechanical epithelial
debridement, conjunctivoplasty and cryopreserved amniotic membrane transplantation,
excimer laser phototherapeutic keratectomy, and cross-linking. In the future, gene therapy and
specific chemotherapy of AK may well be developed.

Keywords: Acanthamoeba, Acanthamoeba keratitis, contact lenses, penetrative keratoplasty,
eximer-laser phototherapeutic keratectomy, cross-linking

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