**5. When the clinician should suspect** *Acanthamoeba* **keratitis?**

It is known, that the emerging vision-threatening AK is difficult to diagnose because clinical manifestations are similar to those observed in the course of other infectious eye diseases.

In anamnesis, in the early stage of this eye disease - patients are complaining of photophobia, excessive tearing, and reduced visual acuity; the clinical manifestations of this keratitis may also include redness and eyelid edema [13,17,50,54].

Particularly, if a presence of any foreign particles will be excluded, appearing of excruciating eye pain with intensity incommensurate with degree of corneal deterioration may suggest that *Acanthamoeba* infection develops; however, the pain not always occurs. As a rule, AK should be suspected if, in anamnesis, the contact lens wear, a history of swimming in a lake, and in recreational pools while contact lenses wearing, exposure to soil, any case of corneal trauma, surgical procedures are reported to clinician [12,18]. However, according to different reports and own experience, the amoebic etiology of the keratitis cannot be excluded in patients with above mentioned symptoms and history, previously unsuccessfully treated in ophthalmic units with antiviral, antibacterial and/or antifungal medications that delayed proper diagnosis and the suitable therapeutic management [17,50,55].
