Nosematosis of the Cornea

Abstract

• A 26-year-old woman underwent enucleation of a blind, painful eye because of a perforated corneal ulcer. Histopathologic examination of the eye disclosed an acute, necrotizing keratitis surrounding myriad small (2.5 to 3 × 4.5 to 5 μm), oval, faintly visible structures. Under polarized light, they were partially birefringent and stained intensely positive with the acidfast technique. The organisms were located mainly within the cytoplasm of histiocytes in the deep corneal lamellae. They were interpreted as a protozoa of the genusNosema. The diagnosis was confirmed by electron microscopic studies. The distinguishing features betweenNosemaspecies andEncephalitozoonare discussed. To our knowledge, this is the second documented case of corneal nosematosis.