Fungi are eukaryotic organisms which have different ribosome, nuclear structure, and cellular wall composition from bacteria. They are usually divided into yeasts and molds. Yeasts are typically round or oval and reproduce by budding. They include Candida, Cryptococcus, Blastomyces, and Coccidioides species. Molds are composed of tubular structures called hyphae and grow by branching in a longitudinal extension. They include Aspergillus and the agents of mucormycosis. There are also dimorphic fungi, which grow in the host as yeasts but in vitro as molds, and they include Histoplasma and Blastomyces. Fungi are ubiquitous in nature, but only a limited number of fungal species causes human infection, especially in eye in the form of fungal retinitis and endophthalmitis. The most common organisms that cause fungal infection are the Candida species, followed by Aspergillus species.