A 44-year-old man presented with a right central retinal vein occlusion and malignant hypertension. Investigations revealed Conn syndrome from an aldosterone-secreting adrenal gland adenoma. Conn syndrome is the most common form of primary aldosteronism, which causes 15% of secondary hypertension. Untreated Conn syndrome is associated with life-threatening cardiovascular complications. It has not previously been described in association with central retinal vein occlusion.