In vivo confocal microscopy and in vitro culture techniques as tools for evaluation of severe Acanthamoeba keratitis incidents

Amphizoic amoebae belonging to the genus Acanthamoeba are known as etiological agents of sight-threatening Acanthamoeba keratitis. The leading risk factor for the development of this serious human disease is contact lens wearing which popularity increases worldwide, also in Poland. The disease with active epithelial inflammations, corneal ulcers, including loss of the visual acuity is a serious medical problem as an emerging threat for the public health related to improper contact lens hygiene. The treatment of the amoebic keratitis is difficult, often unsuccessful due to delayed proper diagnosis. The clinical picture of the disease, often with severe course is nonspecific, similar to that occurring in viral, fungal or bacterial keratitis, thus clinical symptoms alone are not sufficient to identify the causative agent of the amoebic infection. Early diagnosis is decisive for the suitable therapeutic management and the treatment efficacy. In our studies, several complicated, difficult to treat Acanthamoeba keratitis incidences pertaining Polish patients using contact lenses have been retrospectively analyzed in terms of the usefulness of non-invasive methods of in vivo confocal microscopy and in vitro culture techniques applied for diagnosis. Hyper-reflective double-walled spherical Acanthamoeba cysts, with a more reflective outer wall were detected in the epithelium and anterior layers of the corneal stroma. In vivo confocal microscopy, if available, may be a valuable, sensitive tool for diagnosis in late identified severe infections mainly with strong viability strains, however confoscan may offer limited value at lowintensity amoebic infections. The microscopic visualization of amoebae in slides prepared directly from corneal scraping and laboratory examinations of specimens from in vitro cultivated corneal isolates allow to confirm or verify results of in vivo examinations, furthermore to identify directly the pathogens and to clarify previous misdiagnoses.