Fungi may infect the cornea, orbit and other ocular structures. Species of Fusarium, Aspergillus, Candida, dematiaceous fungi, and Scedosporium predominate. Diagnosis is aided by recognition of typical clinical features and by direct microscopic detection of fungi in scrapes, biopsy specimens, and other samples. Culture confirms the diagnosis. Histopathological, immunohistochemical, or
DNA-based tests may also be needed. Pathogenesis involves agent (invasiveness, toxigenicity) and host factors. Specific antifungal
therapy is instituted as soon as the diagnosis is made.
Amphotericin B by various routes is the mainstay of treatment for life-threatening and severe ophthalmic
mycoses. Topical
natamycin is usually the first choice for filamentous fungal
keratitis, and topical
amphotericin B is the first choice for yeast
keratitis. Increasingly, the
triazoles itraconazole and
fluconazole are being evaluated as therapeutic options in ophthalmic
mycoses. Medical
therapy alone does not usually suffice for invasive fungal orbital
infections,
scleritis, and
keratitis due to Fusarium spp., Lasiodiplodia theobromae, and Pythium insidiosum. Surgical
debridement is essential in orbital
infections, while various
surgical procedures may be required for other
infections not responding to medical
therapy.
Corticosteroids are contraindicated in most ophthalmic
mycoses; therefore, other methods are being sought to control inflammatory tissue damage.
Fungal infections following ophthalmic
surgical procedures, in patients with
AIDS, and due to use of various ocular
biomaterials are unique subsets of ophthalmic
mycoses. Future research needs to focus on the development of rapid, species-specific diagnostic
aids, broad-spectrum fungicidal compounds that are active by various routes, and therapeutic modalities which curtail the harmful effects of fungus- and host tissue-derived factors.