RESUMO
The role of Acanthamoeba species in causing keratitis is increasingly recognized, that in this study 9 cases out of 28 cases [32.1%] of resistant keratitis were investigated and proved having Acanthamoeba keratitis. This high rate was discussed on clinical and laboratory basis. The cases were presenting to the Ophthalmology Clinic of Zagazig University Hospital. Thorough ophthalmological examination and accurate parasitological investigations including: culturing of the corneal isolates on non nutrient agar and microscopic examination of direct, wet and unstained smears, also doing flagellation test, were performed These methods revealed and confirmed the presence of trophozoite, precyst and cyst stages of Acanthamoeba in nine corneal scrapings.The cases were 7 males and 2 females, aged from 35-75 years, eight from rural areas and one from urban area. The major predisposing risk factor was contaminated minor eye trauma [44.4%] followed by foreign body [22.2%], while contact lens wear, contamination of the eye by sewage and unrecognized cause showed minor roles as risk factors. Regarding the clinical presentations of Acanthamoeba keratitis, the symptoms [ocular discomfort, photophobia, lacrimation.. etc] were non specific and simulated those of most corneal infections, while the signs, 2 cases [22.2%] showed anterior stromal keratitis, in the form of ring infiltration of the stroma, 3 cases [33.3%] showed central corneal haze with a fine granular appearance, 3 cases [33.3%] showed extensive and deep stromal infiltrates and an extensive corneal abscess with superficial ulceration were recorded in one case. Therefore, amoebic keratitis should be considered in the differential diagnosis of resistant keratitis especially those not responding to treatment for long duration, combined with a suggestive history [risk factors especially eye trauma]. So, cultures for Acanthamoeba should be routinely done for all cases of keratitis, for early diagnosis, as detection of Acanthamoeba species in corneal scrapings provides the main diagnostic feature