Case description

A 64-year-old Indian man presented to the emergency department with a 3-day history of worsening blurred vision in his right eye. This was accompanied by dull right periocular pain exacerbated by eye movement. Ten days before the onset of visual loss, he had developed malaise, fever and productive cough, treated with ciprofloxacin and azithromycin. There was no recent history of weight loss, rash, shortness of breath, joint pain or other systemic symptoms.

He reported two prior episodes of bilateral visual loss at age 56 and 59 years, of similar temporal evolution and severity to the current episode. Both previous episodes had also been preceded by symptoms suggesting a viral illness and had been diagnosed as bilateral optic neuritis based on the clinical profile and presence of optic nerve enhancement on MR scan of brain. His serum anti-aquaporin-4 antibodies (associated with neuromyelitis optica (NMO)) were negative during each prior episode. He was treated with intravenous corticosteroids on both prior occasions and his vision had recovered to normal within days. Other pertinent medical history included hypothyroidism and intestinal tuberculosis (TB) infection 35 years previously that had manifested with fevers, weight loss and an abdominal mass, and treated with antituberculous therapy for a few months.

On examination in the emergency department, we noted symmetric pupils, with slow right pupillary reaction and a subtle right afferent pupillary defect. High contrast visual acuity via snellen chart was 20/100 in the right eye and 20/25 in the left eye. He could correctly identify 1 of 10 Ishihara plates with each eye. Dilated slit lamp examination showed bilateral symmetric cataracts but no abnormalities of the optic nerve heads or retina. There was no ophthalmoplegia, but extremes of horizontal gaze provoked right retro-orbital pain. The remaining neurological examination (including detailed examination of other cranial nerves) was entirely normal. …