The fluid dynamics of phacoemulsification require constant irrigation through the sleeve around the ultrasound tip with minimal egress of fluid through the incisions. Coaxial irrigation with balanced salt solution cools the phaco tip, preventing heat buildup and consequent damage to adjacent tissue.
Another important purpose of irrigation is maintenance of a stable anterior chamber during surgery. The surgeon can adjust intraocular pressure and anterior chamber depth by changing the infusion pressure. In some phaco machines, infusion pressure is controlled by the height of the irrigation bottle, with gravity providing the force necessary to increase the level of irrigation. Air infusion can also be used to pressurize the irrigation bottle. In other phaco machines, infusion pressure is controlled by a collapsible saline bag that is compressed by pressure plates that provide continuous feedback to maintain a stable anterior chamber.
Some surgeons put additives in the irrigation bottle to maintain pupillary dilation. Others add antibiotics to the bottle as prophylaxis against endophthalmitis (see the section Antimicrobial Therapy in Chapter 7).
Donnenfeld ED, Whitaker JS, Jackson MA, Wittpenn J. Intracameral ketorolac and phenylephrine effect on intraoperative pupil diameter and postoperative pain in cataract surgery. J Cataract Refract Surg. 2017;43(5):597–605.
Excerpted from BCSC 2020-2021 series: Section 11 - Lens and Cataract. For more information and to purchase the entire series, please visit https://www.aao.org/bcsc.