Chronic microsporidial stromal keratitis in an immunocompetent, non-contact lens wearer

An 82-year-old healthy man with unilateral chronic stromal keratitis, initially diagnosed to have viral keratitis and refractory to medical therapy, showed numerous oval, microsporidial organisms, measuring 4-5 m in length in the corneal biopsy. Penetrating keratoplasty, followed by treatment with systemic albendazole and topical propamidine isethionate resulted in resolution of the infection. Electron microscopy of the keratoplasty specimen demonstrated sporoblasts with diplokaryotic nuclei and multiple coils of the filament. The light and electron microscopic features were consistent with microsporidial keratitis.