Ex vivo laser confocal microscopy findings of cultured Acanthamoeba trophozoites

Natsuko Yamazaki,¹ Akira Kobayashi,¹ Hideaki Yokogawa,¹ Yasuhisa Ishibashi,² Yosaburo Oikawa,³ Masaharu Tokoro,⁴ Kazuhisa Sugiyama<sup>1

1</sup>Department of Ophthalmology, Kanazawa University Graduate School of Medical Science, Kanazawa, Japan; ²Department of Ophthalmology, East Washinomiya Hospital, Kuki, Japan; ³Department of Medical Zoology, Kanazawa Medical University, Kahoku, Japan; ⁴Department of Parasitology, Kanazawa University Graduate School of Medical Science, Kanazawa, Japan

Purpose: The purpose of the current study was to investigate ex vivo laser confocal microscopic findings of cultured Acanthamoeba trophozoites obtained from Acanthamoeba keratitis patients.
Methods: Eight cultured samples of Acanthamoeba trophozoites from eight eyes of seven patients (mean age, 26.9 years; age range, 18–52 years) were used. Seven samples were from corneal scrapings of Acanthamoeba keratitis patients and one sample was from the solution in a soft contact lens case. Ex vivo laser confocal microscopy was performed to qualitatively evaluate the shape and degree of light reflection of the living Acanthamoeba trophozoites.
Results: Ex vivo laser confocal microscopy demonstrated highly reflective, high-contrast Acanthamoeba trophozoites with no walls (mean size, 25.4 µm; range, 17.1–58.5 µm). The shapes of the trophozoites were highly pleomorphic, and some showed characteristic acanthopodia by laser confocal microscopy.
Conclusion: Ex vivo laser confocal microscopy was effective in demonstrating cultured Acanthamoeba trophozoites of various shapes and sizes. The observations of the current study may be helpful when similar structures are identified under in vivo conditions.

Keywords: Acanthamoeba, trophozoite, laser confocal microscopy