Case presentation

A 72-year-old man had a 2-week history of gradual onset and progressively worsening blurring of right eye vision with retro-orbital pain, but no rhinorrhoea, nasal obstruction or facial pain. He had no fever, infective symptoms, loss of weight or appetite, and no rashes, joint pains, headaches, scalp tenderness or jaw claudication. There was a history of diabetes mellitus, hypertension and hyperlipidaemia. Family history was unremarkable. On examination, there was no eye redness. His right visual acuity was reduced to light perception. There was a grade 3 right relative afferent pupillary defect. Both optic discs were pink with a cup-to-disc ratio of 0.4 and the anterior segment examination was normal. Visual field examination could not be quantified due to his poor vision. The remaining neurological examination was normal. His clinical signs suggested a right retrobulbar …