Unilateral optic disc swelling caused by numerous systemic, orbital and ocular causes, non arteritic anterior ischemic optic neuropathy (NAION) was the most common cause of unilateral disc swelling reported in this study. It was associated systemically with diabetes mellitus, systemic hypertension, hyperlipidemia, hypotension, ischemic brain changes, carotid tree arteriosclerotic changes, ocular associations reported are disc at risk, diabetic retinopathy, and after phaco ischemic neuropathy.