Direct microscopy; viable trophozoites contain a vacuole, which empties itself several times each minute. They are between 20-40 •m in size and assume different shapes. Cysts, 12-18^m in diameter, polygonal with a double cyst wall, similar to talc crystals.
The cytoplasm of Giemsa-stained trophozoites, contain several vacuoles. The nucleus is centrally placed and contains a large endosome.
Negative findings do not exclude Acanthamoeba spp. infections. The sensitivity for culture of corneal scrapes is about 76%. Deep biopsy of the cornea gives a higher sensitivity (Auran et al. 1987).
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