Which of the following method is used to make a diagnosis of corneal ulcer caused by acanthamoeba?

Acanthamoeba keratitis is caused by a free lying amoeba found in soil, fresh water, well water, sewage and air. Corneal infection occur from direct contact with water contaminated with this organism. Diagnosis of acanthamoeba can be made by any of the following methods: KOH mount is useful for recognition of acanthamoeba cysts. Calcofluor white stain: stains cysts of acanthamoeba bright apple green under fluorescence microscope. Lactophenol cotton blue stain can demonstrate acanthamoeba cysts. Culture on non nutrient agar may show trophozoites within 48 hours. Ref: Ophthalmology By A. K. Khurana page 129.