Case 234. 

Scanning electron micrograph of trophozoites of Acanthoamoeba castellani
　 　 　 　
　 The surface of the acanthoamebic trophozoites reveals acanthopodia formation (irregular process-like structure). 　
　 　 　 　

　

 　 Acanthamoeba is a ubiquitous free-living protozoa widely distributed in the water and soil. Keratitis is closely related to wearing a contaminated soft contact lens.