Shimmura-Tomita M, et al. - Experts ascertained the risk factors and clinical signs for severe Acanthamoeba keratitis (AK) by comparing severe cases with mild cases with good prognosis. They reviewed the medical records of 10 cases of AK (five males and five females) referred to the hospital and classified cases into two groups. For severe AK, aging may be a possible risk factor. A possible sign of severe AK is the presence of keratoprecipitates. In patients with comorbidities such as diabetes mellitus and bacterial infection, attention is also required.