Beware the Retrobulbar Optic Neuritis Diagnosis.

A 48-year-old gentleman presented to the ophthalmology department with progressive monocular vision loss, a relative afferent-pupillary defect, decreased color perception, headache, proptosis, and retro-orbital pain. This particular patient's demographics and disease course did not suggest a "typical" retro-bulbar optic neuritis and highlights the importance of avoiding presumptive steroid treatment in such "atypical" cases. Further investigations revealed a compressive optic neuropathy secondary to an orbital tumor (B-cell non-Hodgkin's lymphoma) and were subsequently treated by a multi-disciplinary approach. Early detection and commencement of treatment is a crucial determining factor in orbital lymphoma prognosis and is therefore an important differential diagnosis for an ophthalmologist to consider when evaluating patients with "atypical" optic neuropathies.