Ischemic optic neuropathy is among the most common causes of serious impaired vision in the middle-aged and elderly population in the western world. The current study focuses on a subgroup of ischemic optic neuropathy, the so-called non-arteritic ischemic optic neuropathy (NAION). Although the exact pathogenesis of NAION has not been fully clarified it is known that patients with cardio-vascular risk factors such as hypertension, diabetes mellitus and dyslipidemia have also an increased risk to develop NAION. Along this line of thought it has been shown that patients with a history of NAION in one eye have an increased risk to develop NAION also on the contralateral eye. However, clinical studies investigating ocular perfusion abnormalities in patients with NAION are sparse and even contradicting. Thus, the current study seeks to measure ocular blood flow parameters in patients with a history of NAION and compare it to healthy age-matched subjects.

Inclusion criteria for healthy subjects:

• Men and women aged over 18 years
• Non-smokers
• Normal findings in the medical history unless the investigator considers an abnormality to be clinically irrelevant
• Normal ophthalmic findings, ametropy < 6 Dpt.

Inclusion criteria for patients with NAION:

• Men and women aged over 18 years
• History of NAION in one eye
• Normal ophthalmic findings, ametropy < 6 Dpt.
• Adequate visual acuity to allow participation in the ocular blood flow measurements
• A potential participant has to be on stable doses of all medications he/she is taking because of consisting illnesses according to medical history for at least 30 days prior inclusion, if considered relevant by the investigator.

Any of the following will exclude a healthy subject from the study:

• Current ocular disease or history of NAION
• Presence or history of a severe medical condition as judged by the clinical investigator
• Untreated Arterial hypertension
• History or family history of epilepsy
• Presence of any abnormalities preventing reliable measurements in the study eye as judged by the investigator
• Best corrected visual acuity < 0.5 Snellen
• Ametropy ≥ 6 Dpt
• Pregnancy or planned pregnancy
• Alcoholism or substance abuse

Any of the following will exclude a patient from the study:

• Presence or history of a severe medical condition other NAION as judged by the clinical investigator
• Untreated Arterial hypertension
• History or family history of epilepsy
• Presence of any abnormalities preventing reliable measurements in the study eye as judged by the investigator
• Best corrected visual acuity < 0.5 Snellen in the non-affected eye
• Ametropy ≥ 6 Dpt
• Pregnancy, planned pregnancy
• Alcoholism or substance abuse