Impression Cytology in Eyes with Clinical and Confocal Scan Features of Acanthamoeba Keratitis

Purpose: to report impression cytology findings in specimens obtained from eyes with clinical and confocal microscopic features of acanthamoeba keratitis (ak). methods: in this interventional case series, impression cytology was obtained from corneas of patients with clinical and confocal microscopic features indicative of ak. specimens were stained with periodic acid-schiff/papanicolaou (pas/pap) and examined for the presence of pas-reactive acanthamoeba cysts and/or hyperchromatic pear-shaped trophozoites. all specimens were then decolorized and re-stained with calcofluor white (cfw) for the presence of chemofluorescent cysts. results: fifty-six eyes of 50 patients with mean age of 25.5±9.3 (range, 17 to 78) years were evaluated. forty-one (82%) cases were female and 51 (91.1%) eyes had history of contact lens wear. pas-reactive acanthamoeba cysts and/or hyperchromatic pear-shaped trophozoites were identified in 53 eyes (94.6%), 2 of which demonstrated only trophozoitelike structures. cfw staining was able to reveal the presence of chemofluorescent cysts in all 51 specimens (91.1%) in which cysts had been demonstrated with pas/pap staining. trophozoites were not detected with cfw due to background staining of the cellulose acetate strip used for impression cytology. conclusion: corneal impression cytology, stained with pas/pap or with cfw, successfully detects acanthamoeba and can be employed for early noninvasive diagnosis of ak.