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.