Clinical/microbiological records of 194 patients with microbiological/histopathological diagnosis of Acanthamoeba keratitis from 2007-11 without history of contact lens wear were retrospectively studied. Positive results on corneal scraping and culture were analyzed. Patients were divided based on positive first smear report (group 1/2) and time of presentation (group 3/4). Primary and secondary outcome measures were microbiological positivity rate and to find any possible differences at presentation in sub-groups, respectively. Mean age of patients was 38.5 ± 13.7 years, M:F was 1.8:1. Positivity of first smear examination was 82% and was 98% overall in three scrapings. Ten percent potassium hydroxide with calcoflur white was better than Grams stain (87.1 versus 71.1%). Culture was positive in 79.4% cases. Sub-group analysis showed clinically/demographically similar groups 1 and 2 (p > 0.05). Patients who presented within a month of symptoms (group 3) were significantly younger than others (p = 0.012). Microscopic diagnosis of non-contact-lens Acanthamoeba keratitis is reliable.
Keywords: Acanthamoeba keratitis; microbial keratitis; microscopy; non-contact-lens; time of presentation.