Unilateral anterior neuritis
Optic neuritis is most common between the ages of 18 and 45, and usually presents with unilateral vision loss, color vision impairment, and visual field defects. In adults, the optic disc is usually normal (retrobulbar optic neuritis); in children and young adults, the presence of an edematous optic disc is more common (papillitis or anterior neuritis). The presence of multiple sclerosis should always be ruled out.