Altitudinal Visual Defect as the Initial Sign of Optic Neuritis: A Case Report

Optic neuritis (ON) is the most common optic neuropathy in adults and is frequently seen together with multiple sclerosis, manifesting itself mainly as painful diffuse field loss or central scotomas. However, it could be encountered in various other inflammatory, demyelinating, infectious, and autoimmune conditions that could be broadly classified into two groups: typical and atypical ON. On the contrary, painless vision loss, especially altitudinal visual field defects (AVD), is commonly observed in ischemic optic neuropathies (ION), mostly in patients with vascular risk factors or history of giant cell arteritis. Although rare, AVD can be the initial sign of ON and inflammatory demyelinating process. Herein, we report a case of a 17-year-old patient with ON presenting with painless AVD and provide a brief review of the mechanisms involved in typical and atypical ON and ION.