Correlation between histopathologic features and clinical outcomes of acanthamoeba keratitis

Abstract

Objective: To study the relationship between the clinical characteristics and the histopathological changes in acanthamoeba keratitis. Methods: In this retrospective study, the clinical data and histopathological features of 15 Acanthamoeba keratitis patients (15 eyes) treated in Henan Eye Hospital were collected and analyzed. There were 8 males and 7 females. Mean age was 49.2 years old. The corneal specimens were stained with hematoxylin eosin, periodic acid-schiff, Gomori's methenamine silver, Gram and Gimsa respectively. The pathological changes and characteristics were observed under microscope, to analyze the relationship between histopathology and clinical features. Results: All patients had moderate conjunctival congestion. Five patients showed corneal ring stromal infiltration, 8 had central corneal ulcers, 1 had corneal opacity, and 1 had a matrix ulcer. We found corneal neovascularization around the ulcer in 4 eyes and a dense ulcer in 2 eyes. Histopathological examinations with hematoxylin-eosin, periodic acid-Schiff, Gomori's methenamine silver, Gram and Giemsa stainings revealed round or oval amoebic cysts and amebic trophozoites which were of an elongated oval, spine-or spear-like. Twelve patients (80%) showed corneal stromal purulent inflammation infiltrated by neutrophils. Many degenerated amoebic cysts were found. Degeneration and necrosis of corneal stromal fibers were observed in 3 eyes (20%). There were no neutrophils. Amoebic cysts were seen in necrotic tissue. Ten eyes (66.7%) had no inflammatory cell infiltration areas, with edematous or mildly degenerated corneal fibers, scattered or grouped cysts and trophozoites. Conclusions: Clinical manifestations of acanthamoeba keratitis are various. Acanthamoeba cysts and trophozoites also exist in the transparent corneal area on the histopathological examination. This is important for the therapeutic outcomes. (Chin J Ophthalmol, 2021, 57: 939-943).