Filamentous fungi achieved notoriety as an important cause of microbial keratitis in 2005 and 2006 after an outbreak of corneal ulcers related to a contact lens care solution in which the Centers for Disease Control and Prevention reported 318 cases of Fusarium keratitis in the USA, many of which required corneal transplant to restore vision. However, Fusarium and Aspergillus species were already well recognized as important causes of microbial keratitis related to trauma associated with agricultural work rather than contact lens wear. Trauma-induced fungal keratitis has a high prevalence in warm, humid regions of the USA, and in southern and southeastern Asia, especially in India and China. In temperate climates, yeast and especially Candida species are the most common cause of fungal keratitis, although they are often associated with underlying ocular or lid diseases. This article describes studies on contact-lens-associated and trauma-induced keratitis, and reviews animal models of fungal keratitis that identify fungal virulence factors and host immune responses that regulate the severity of disease.
