A clinical case series of Acanthamoeba keratitis diagnosed by a simple technique of detection of motile trophozoites in wet mount preparation

Abstract

Acanthamoeba keratitis is diagnosed fairly late because of lack of early clinical suspicion and unavailability of simple and effective technique for detection of the protozoa in ordinary laboratory settings. The detection of motile trophozoites in wet mount preparation of corneal scraping is probably the best confirmatory test of Acanthamoeba keratitis in ordinary laboratory settings. However, it is not easy to demonstrate motile trophozoites given the fact that the trophozoites rapidly encyst outside living tissue. We employed a protocol of preparation and transport of the wet mount to the nearby laboratory within fifteen minutes whereby optimum chance of demonstration of motile trophozoites was possible. We had been successful to detect the typical amoeboid movement of acanthamoeba in three cases. Healing of ulcers were achieved by an appropriate therapy in all three cases. Visual recovery was good in two out of three cases. To the best of our knowledge, the present case series is the first one in English literature where diagnosis of acanthamoeba keratitis is based solely on detection of motile trophozoites in direct wet mount examination. A careful history and an incisive look into the corneal lesion revealed some clue to suspect the acanthamoeba etiology. Simple laboratory technic employing wet mount microscopy rapidly confirmed the diagnoses. Healing of ulcers were achieved in all three cases by instillation of 0.02% chlorhexidine eye drop. Visual recovery was good in two out of three cases.