A 56-year-old man was referred to our hospital with blurred vision in his right eye in April 2008. On initial examination, his corrected visual acuity was 20/20 in both eyes. The anterior chamber was mildly inflamed, but dense vitreous opacities were present in his right eye and optic neuritis was present bilaterally (Figure 1A and B). Fluorescein angiography showed dye leakage from both optic discs (Figure 1C and D). The results of laboratory examinations were essentially normal, including serum levels of angiotensin-converting enzyme, calcium, gammaglobulin, anti-human T lymphotropic virus-1 antibody, anti-herpes simplex virus antibody, and anti-varicella zoster virus antibody. The patient was weakly positive for tuberculin. A chest x-ray did not show bilateral hilar lymphadenopathy. Examinations according to the criteria for sarcoidosis were negative and tuberculosis was ruled out by our Department of Internal Medicine. His visual acuity had decreased to 20/100 OD, with increased numerous snowball-like vitreous opacities, and mutton-fat keratic precipitates and nodules were observed in the anterior chamber angles. Therefore, he underwent pars plana vitrectomy with a 25 gauge system to remove the dense vitreous opacities, and diluted and undiluted vitreous was obtained to determine the cause of the inflammation. Histiocytes, and epithelioid and multinucleated giant cells were detected by cytology in diluted vitreous samples, but necrotic materials and malignant cells were not detected (Figure 2). He received systemic corticosteroid therapy, and 2 months after surgery, optic neuritis was reduced and his corrected visual acuity had improved to 20/20 OD.