Atypical anterior optic neuropathy caused by toxoplasmosis

PURPOSE: To report atypical anterior optic neuropathy due to toxoplasmosis. METHODS: Interventional case report. A 33-year-old male presented with sudden painless loss of vision and floaters in the right eye. Examination demonstrated a best-corrected visual acuity of 20/200, optic nerve head edema, retinal hemorrhages, and vitreous opacities. RESULTS: Nine days later, a granuloma at the optic nerve head was apparent, and the patient was treated with pyrimethamine, sulfadiazine, folinic acid, and prednisone. Six weeks after initiating therapy, best-corrected visual acuity had improved to 20/25. CONCLUSION: Optic nerve involvement in toxoplasmosis is uncommon and, when it occurs, usually presents with a white inflammatory mass on the optic disk. The current case demonstrates the importance of including toxoplasmosis in the differential diagnosis of unilateral anterior optic neuropathy, even if a focal inflammatory mass is not apparent.