Unilateral Blastomyces dermatitidis Optic Neuropathy

Ophthalmic blastomycosis infections can cause rapid, complete vision loss. Prompt treatment is required, but infections are uncommon and usually are misdiagnosed, often because of lack of biopsy results. Tissue must be biopsied, cultured, or both for a definitive diagnosis. Because virtually all blastomycosis cases begin in the lungs, a chest radiograph or computed tomographic scan should be obtained. Any questionable lung lesion should be biopsied to corroborate possible ophthalmic disease.