The symptoms of Acanthamoeba keratitis can be very similar to other eye infections. These symptoms which can last for several weeks include eye pain, eye redness, blurred vision, light sensitivity, eye irritation and excessive tearing.
Most patients suffer from photophobia, pain and tearing. The pain in early onset of AK is reported to often be severe and disproportionate to the clinical signs. Cases of prolonged Acanthamoeba keratitis are severely debilitating, they can result in a severe sterile ischemic posterior segment inflammation and this can lead to blindness (Awwad ST et al., 2006).
Typically diagnosis includes clinical examination, culture and histology of affected corneal epithelium, while some centres use confocal microscopy.
Early diagnosis greatly improves the outcome. If unrecognised, and infection progresses for 4-8 weeks, there is anterior infiltration which may remain in the central cornea or give rise to a classic ring abscess, accompanied by limbitis, episcleritis and occasionally scleritis. Epithelial scraping may reveal amoeb
a, however, if missed, the infection proceeds to a large, deep infiltrated ulcer.
Identification of Acanthamoeba spp. by PCR was reported to give a sensitivity of 84% compared to 53% for culture positivity. A detailed overview of current methods is presented by Dart et al. (2009).
Picture of a confocal microscope