Non-arteritic ischemic optic neuropathy and supplemental nitric oxide usage

To report a case of Non-Arteritic Ischemic Optic Neuropathy (NAION) in a middle-aged bodybuilder in excellent physiological condition without any signs or symptoms of vasculopathy and a history of nitric oxide supplement usage.

The patient had visual acuity of 20/25 in the right eye, and 20/30 in the left eye, with a relative afferent pupillary defect and dyschromatopsia in the right eye. Visual field testing with Humphrey perimetry demonstrated an inferior altitudinal field defect OD. Fundus examination showed a small cupless disc OD with mild pallor, and a small cupless disc OS. He denied usage of sildenafil or other phosphodiesterase (PDE) inhibitor medications but frequently ingested megadoses of nitric oxide (NO) as part of his bodybuilding regimen.

Nitric oxide supplements act through the same pharmacologic pathway as PDE inhibitors, and this case is suggestive that other vasodilating agents may be similarly associated with NAION.