Fungi are eukaryotic organisms that are ubiquitous in nature. The following 3 classes of fungi are important ocular pathogens: molds, yeasts, and diphasic fungi. Molds, also known as filamentous fungi, are multicellular organisms that form a tangled mass known as the mycelium. From this mass, filamentous projections, known as hyphae, branch out. The hyphae may be septate or nonseptate. Septate hyphae have true divisions, subdividing them into several cells, while nonseptate hyphae have no true divisions. Common septate filamentous fungi are Aspergillus, Fusarium, Cephalosporium, Paecilomyces, and Penicillium species. The nonseptate filamentous fungi include the Mucor species.
Yeasts are unicellular organisms that may develop pseudohyphae. Candida and Cryptococcus are the important ocular pathogens. The diphasic fungi exist in 2 forms, yeast and mold. Important ocular pathogens include Histoplasma, Blastomyces, and Coccidioides.
Endophthalmitis refers to intraocular inflammation involving the vitreous and anterior chamber of the eye. In most cases, endophthalmitis results from an infectious organism. Fungal endophthalmitis can be divided into the less common endogenous infections and the more common exogenous infections.
Endogenous fungal endophthalmitis represents intraocular dissemination of a systemic fungal infection. Among the different fungal species, Candida species is the most common cause of infection, followed by Aspergillus species.
Risk factors include immunosuppression, intravenous drug abuse, bacterial sepsis, prolonged hyperalimentation, systemic antibiotics, corticosteroid therapy, recent abdominal surgery, malignancy, alcoholism, diabetes mellitus, trauma, and hemodialysis.
Exogenous infections usually are secondary to trauma or surgery. A variety of fungi, including Paecilomyces, Acremonium, and Sporothrix species, has been associated with endophthalmitis following intraocular surgery or trauma. Fungal endophthalmitis is a rare complication after cataract surgery. The most common causative fungal pathogens implicated in fungal endophthalmitis after cataract surgery include Candida species and molds such as Aspergillus and Fusarium species.
There have been recent outbreaks of fungal endophthalmitis associated with contaminated compounded brilliant blue G and triamcinolone.