Objectives: this study aimed to investigate the most common causes of unilateral optic disc swelling and also to identify the ocular and systemic factors associated with each case.
Study design: this was a prospective study in El-Hussein University Hospital and National eye Center (Rod El- Farag).Population: 50 eyes of 50 patients who were suffered from unilateral optic disc swelling were included in this study. Method: personal, medical, family, systemic illness history, smoking, drug and alcohol intake, visual acuity assessment, clinical assessment of the optic nerve function, anterior segment examination, fundus examination, visual field testing, magnetic resonance imaging (MRI) of the orbit and brain and laboratory investigation including fasting blood glucose and 2 hours postprandial, lipid profile, complete blood picture , C reactive protein and ESRwere included. Results: non arteritic anterior ischemic optic neuropathy (NAION) was the most common cause of unilateral disc swelling reported in this study (72%) followed by traumatic optic neuropathy, optic neuritis, disc swelling associated with orbital mass, disc swelling associated with brain mass in the same percentage (6%) followed by disc swelling associated with thyroid ophthalmopathy, disc swelling associated with cilio retinal artery occlusion in the same percentage (2%) with different ocular and systemic associations in each group.Conclusion: the most common cause of unilateral disc swelling In the present study is (NAION), it caused mainly by systemic vascular disorders (DM, HTN and hyperlipidemia).