Light After Darkness: A Case Report of Isolated Optic Perineuritis.

This is a report on remarkable visual recovery from blindness in a case of isolated optic perineuritis (OPN). A 68-year-old Chinese lady presented with a two-week history of progressive painless bilateral vision loss. Her vision was 6/18 on the right eye and no perception of light (NPL) on the left eye with positive relative afferent pupillary defect (RAPD). Fundus showed hyperaemic and swollen optic disc bilaterally. MRI of the brain and orbit revealed hyperintense periventricular white matter lesions, possibly early changes of multiple sclerosis (MS), and perineural enhancement of optic nerve bilaterally, consistent with OPN. All other investigations were negative. Intravenous methylprednisolone 1g/day for three days was started, followed with oral prednisolone, tapered in three months. At the third month of follow-up, her vision had improved to 6/12 on the left and 6/9 on the right. The hyperaemic and swollen disc has resolved. Intravenous megadose corticosteroid treatment is an effective first-line treatment for OPN.