Prior to phacoemulsification, the lens nucleus must be physically separated from the lens capsule until it can be rotated. Some cortex may stay with either the nucleus or the capsule. Hydrodissection, the injection of fluid to separate the cortex from the capsule, is done to mobilize the nucleus and prevent damage to the posterior capsule (Devgan U. Cataract CoachTM. https://cataractcoach.com/ . Accessed 22 Sept 2024). Hydrodelineation, the injection of fluid in the lens to separate nucleus from the softer epinucleus, allows for better visualization but may not allow the nucleus to rotate. Either one or both can be done, but the nucleus must be mobile afterwards.