 Hepatic impairment, severe renal impairment, lymphedema conditions such as Milroy disease, Meige lymphedema, Hennekam syndrome, Njolstad syndrome, Aagenaes syndrome, and Fabry disease, hypotension or at risk for hypotension, seizures or history of seizures, any significant cardiovascular risk factors and any condition which requires participants to use nitric oxide donors or nitrates in any form, underlying anatomic or vascular risk factor for developing non-arteritic anterior ischemic optic neuropathy NAION including low ocular cup to disc ratio, diabetes, hypertension, coronary artery disease, or hyperlipidemia Participants with Down syndrome, Turner syndrome and Noonan syndrome will be considered on a case-by-case basis. 