Eyeworld

EW CATARACT 48 September 2016 ultrasound energy on the Centurion Vision System (Alcon, Fort Worth, Texas) involve adjusting the OZil IP or longitudinal phaco power added at occlusion. "Compared to standard cases, I lower the threshold of activation or percent occlusion, increase the later steps, such as placing capsular retractors, easier. If a patient has a dense cata- ract with stable zonules, Dr. Burger said she would increase ultrasound energy, adding longitudinal phaco to break up the lens. She added that the most efficient changes in Expecting continued from page 46 Brunescent cataracts O ne of the cases in the "PhacoFun: Expecting the unexpected" webinar described the example of a young eye surgeon encoun- tering a 4+ brunescent cataract. Dr. Chang recommended trypan blue dye to visualize the anterior capsule during the capsulorhexis step. Dr. Zavodni pointed out that it's not too late to put in dye even after adding viscoelastic. In this fictitious example, the surgeon used dye and proceeded with the capsulorhexis, but then noticed viscoelastic oozing out of the main incision. Dr. Kim said during the webinar that this indicates a shallowing chamber. In brunescent and intumescent cataract cases, he said the intracapsular pressure can be high, causing the anterior cap- sular surface to be convex. There is also the possibility that very dense lenses won't have an epinucleus. "You're basically doing a capsulorhexis on top of a hill … you want to keep that hill as flat as possible so you'll probably have to supple- ment with a lot of viscoelastic," Dr. Kim said, adding that a cystotome or micro-cross-action forceps might be better than traditional forceps in this case to keep the chamber stable and flatten the anterior capsule. Prior to initiating the hydro-steps and sculpting, Dr. Chang rec- ommended that surgeons first take a "mental snapshot" of the capsu- lorhexis size and shape to remember where its boundaries are. He also offered advice on preventing wound burns. "In practice, a severe wound burn happens when the phaco tip becomes clogged from the molasses-like mixture of dispersive OVD and brunescent nuclear emulsate. As a result, nothing exits the an- terior chamber and no gravity dependent inflow can enter from the infusion bottle. If there is no fluid inflow or outflow to cool the tip, it unfortunately takes only a microsecond of ultrasound heat to coagulate tissue," Dr. Chang said. "One needs to first aspirate the viscoelastic that is directly above the central, anterior endonucleus prior to initiating sculpting. Like blowing leaves off a sidewalk, this removes the cortical debris and epinucleus to provide a clear view of the firm endonuclear surface. In addition, as you start sculpting, you are not directly mixing the nuclear emulsate with viscoelastic. The viscoelastic needs to coat the endothelium, but we don't want it to coat the endonucleus. "High vacuum requires tip occlusion, but allows us to firmly grip quadrants for chopping and to manually separate hemi-fragments to break them apart," Dr. Chang said. Deeply embedding the phaco tip with short pulses or single bursts of ultrasound will usually give a better seal around the tip compared to using continuous phaco, which tends to erode away the nuclear material surrounding the tip. Dr. Chang uses prolene iris retractors to stabilize the bag. Dr. Chang performs a vertical chop technique, using a single burst mode with high vacuum. Source (all): ASCRS "Severe phimosis contraction can lead to IOL subluxation and decentration. Thus, in cases of weakened zonules, many surgeons have adopted a two-point fixation technique in which the haptics of a three-piece IOL are inserted into the sulcus space and the optic is cap- tured posteriorly in the curvilinear rhexis. Such a technique stents the circular rhexis, preventing progres- sive phimosis," he said. Dense cataract For the sculpting surgeon working with a case of dense cataract and zonular instability, Dr. Kim suggest- ed increasing phaco power to make cutting more efficient. In cracking, Dr. Kim cautioned that the surgeon should only use lateral forces so as to not put downward stress on the zonules. Dr. Burger suggested using chopping techniques in these cases and recommended removing quadrant fragments from the bag at the iris plane for emulsification to avoid post-occlusion surge. Dr. Kim advised surgeons removing their last fragments to keep away from the posterior capsule and use a second instrument deep in the bag to make sure the posterior capsule doesn't come up and rupture. He also sug- gested putting a dispersive visco- elastic in the bag to act as a weight keeping the posterior capsule down. Dr. Zavodni said staining the an- terior capsule with trypan blue could make creating the capsulorhexis and

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