Corneal microsporidioses: characterization and identification.

Two ocular infectious disorders attributed to Microsporidia have been observed. They differ in that one infection involves the corneal stroma leading to corneal ulceration and suppurative keratitis whereas the other infection involves the conjunctival and corneal epithelium. The corneal stromal infection is caused by a binucleated oval spore that is Nosema-like in character. The conjunctival and corneal epithelial infection occurs in HIV-sero-positive individuals and is caused by a spore containing a single nucleus that is a member of the genus Encephalitozoon. Characteristics of these genera and the above-mentioned infections are presented.