EyeWorld India December 2018 Issue

Breaking down the nucleus by Stefanie Petrou Binder, MD EyeWorld Contributing Writer Special nucleofractis approaches for different types of lens nuclei can improve surgical efficacy and help preserve the integrity of the capsule F resh advice from a seasoned surgeon can help keep surgeons on their toes. Speaking on nucleus management issues at the 22nd ESCRS Winter Meeting, Richard Packard, MD , Wind- sor, U.K., offered tactical pearls on how to use a variety of phaco- emulsification approaches for nuclei of different densities. “Now that we know how the phaco machine works, we have to understand how to best use it on the nucleus,” Dr. Packard said. “In order to be a complete phaco surgeon, a variety of alternate techniques are required to deal with nuclei of differing densities: soft, medium, and hard. When dealing with the nucleus, mechan- ical separation minimizes energy usage and chopping works best for dens nuclei. White nuclei can be brittle, and multiple separa- tions may be needed to complete a chop. It is important to use power modulation to minimize energy dispersion during phaco. Surgeons should be flexible about varying their technique mid-case and have a range of options for the various types of nuclei.” Divide and conquer This four-quadrant nucleofrac- tis technique is the mainstay of phaco surgery for many surgeons. When the surgeon begins to sculpt, it is important to minimize the movement of the globe by the correct use of power and by pressing the foot pedal without pushing the nucleus, which can disrupt zonules. With a Kelman tip, the surgeon’s hand needs to be held somewhat lower because of its curve, otherwise the tip might get occluded as the bevel is easily buried in the nucleus. Lowering the hand is easier when operating temporally, but when operating superiorly, the surgeon needs to extend the patient’s neck, drop- ping the head a bit, to gain good access to the eye over the brow. “The important thing with sculpting is to keep the bevel exposed to avoid occlusion, which will cause the nucleus to move for- ward.” Dr. Packard said. “We want smooth passes. For trainees, I set the ultrasound power at 30–70% on the Infiniti and Centurion ma- chines [Alcon, Fort Worth, Texas]. You need to be aware of the diam- eter of the phaco tip and depth of the nucleus to create the trench at an appropriate depth. One of things I encourage to help limit pushing the nucleus is to preset a power range so that as soon as foot position 3 is reached, power is engaged. Also, you want to lift the phaco tip after the center of the nucleus is passed to prevent sculpting through the nucleus to the other side. This is particularly important in softer cataracts with relatively little density.” Cracking the nucleus needs the right ergonomics. The long axis of the trench should bisect the surgeon’s instruments, which are positioned at the bottom of the trench. “You are going to go down to the bottom of the trench and separate, but you need to push back though before push- ing sideways so it cracks from the bottom, and allow time for the crack to propagate, especially with harder cataracts. To get a good crack in the nucleus, you want an equal and opposite pull on either side,” he explained. To remove segments, Dr. Pack- ard buries the phaco tip at mini- mal ultrasound power and allows the vacuum to build. The sound from the machine lets you know when you’ve reached maximal vacuum with full occlusion. Then the surgeon can pull segments centrally, for removal, in the safe area in the deepest part of the anterior chamber. This is repeated in each of the quadrants. Chopping “I use multiple chopping ap- proaches, often mixing them as the situation demands,” Dr. Packard explained. “Each ap- “ In order to be a complete phaco surgeon, a variety of alternate techniques are required to deal with nuclei of differing densities: soft, medium, and hard. ” - Richard Packard, MD continued on page 42 EWAP CATARACT/IOL 41 December 2018