Phacoemulsification: Principles and Techniques

Abstract

Phacoemulsification is the principle of using ultrasound energy to break apart and remove the lens of an eye through a small incision and is one of the most important tools for the cataract surgeon. It has enabled increased efficiency of cataract surgery and improved outcomes for patients. It is critical that surgeons not only become familiar with the tools used during phacoemulsification but also become familiar with adjusting machine parameters, including aspiration, vacuum, and power, in order to optimize cataract surgery. These parameters can be delivered in a variable linear fashion or in a fixed fashion. Furthermore, there are three ways to deliver ultrasound power: continuous, pulse, and burst. Continuous applies constant ultrasound energy, while pulse and burst provide intermittent ultrasound energy. Pulse and burst can minimize overall ultrasound time and energy and can improve efficiency of surgery. The magnitude and mechanism of aspiration, vacuum, and ultrasound power transfer need to be optimized for different tasks during cataract surgery such as sculpting, chopping, and nucleus removal. Sculpting carves out portions of the nucleus and typically only needs low levels of vacuum and aspiration. Chopping mechanically splits the nucleus into smaller fragments and requires high levels of vacuum. During nucleus removal, surgeons can elect to use either continuous, pulse, or burst ultrasound modes to optimize efficiency. Irrigation, aspiration, and vacuum play a vital role in control of fluidics. Fluidics is influenced by pump type, and the most common types of pumps are peristaltic and venturi pumps. Flow into the eye must be equal to flow out of the eye, and surgeons need to prevent surge which can cause anterior chamber collapse and damage to ocular structures. Viscoelastics are also used in order to protect ocular structures from ultrasound energy and aid with anterior chamber inflation. Hydrodissection and hydrodelineation use fluid to separate the capsule and nucleus, creating a nucleus that can be easily rotated within the capsule. This aids nucleofractis which is the cracking of the nucleus into fragments to create smaller lens fragments. There are multiple techniques for phacoemulsification, and it is valuable for surgeons to have an arsenal of methods to employ in various challenging cases. Common phacoemulsification methods include the divide and conquer, phaco chop, phaco flip and chop, stop and chop, and pre-chop techniques. Finally, removing the cortex and polishing the capsular bag are achieved through irrigation and aspiration. Understanding the basic principles of phacoemulsification and developing fundamental techniques enable the cataract surgeon to adapt to challenging cases and to new innovations in the field of phacoemulsification.