Non-arteritic ischemic optic neuropathy and supplemental nitric oxide usage

PURPOSE: 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. OBSERVATIONS: 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. CONCLUSIONS: 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.