Cystoid macular oedema (CMO) is the accumulation of fluid in the central retina (the macula) due to leakage from dilated capillaries. It is the most common cause of poor visual outcome following cataract surgery. The exact cause is unclear. Acute CMO, defined as oedema of less than four months duration, often resolve spontaneously. CMO that persists for four months or more is termed chronic CMO. Different types of non-steroidal anti-inflammatory agents (NSAIDs) are used in the treatment of CMO which may be delivered topically or systemically.