CRVO (Central Retinal Vein Occlusion) occurs when the main retinal vein gets blocked, leading to sudden vision issues. Types include non-ischemic and ischemic CRVO. Causes range from hypertension, diabetes, glaucoma, blood disorders, and age-related vascular changes. Diagnosis needs both ocular tests (OCT, Fundus exam, FFA) and systemic tests (BP, sugar profile, lipid profile, clotting factors). Treatment includes medicines, Anti-VEGF injections, PRP laser, and continuous monitoring. CRVO can recur and requires repeated follow-ups to protect vision.