A sphenoid sinus mucocele simulating as retro bulbar optic neuritis.

A 25-year-old male presented with complaints of sudden diminution of vision with pain on eye movement in the left eye which was diagnosed clinically as retro bulbar optic neuritis. However, magnetic resonance imaging (MRI) showed lesion consistent with sphenoid sinus mucocele. Early surgical removal of mucocele led to complete recovery of vision, contrast and visual field. A high index of suspicion is necessary for intracranial lesions in all cases of retro bulbar neuritis, especially those with atypical symptoms.