Construction of the paracenteses requires the blade to enter the peripheral cornea, parallel to the iris. Collateral damage to surrounding structures including the anterior capsule must be avoided. It must be adequate width to allow a second instrument or cannula to pass freely into the anterior chamber. The response of the anterior chamber/cornea/iris/lens to the paracentesis are important signs to performance of the phacoemulsification and may indicate the need to change the surgical approach.