AUG 2014

EyeWorld is the official news magazine of the American Society of Cataract & Refractive Surgery.

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Page 69 of 82

is less important, and it's more about proximal followability when there is partial occlusion of the phaco tip. Adjusting flow and vacuum for surgical tasks and lens types Another time to consider flow and vacuum is with sculpting. When sculpting, you want a fairly low vac- uum of 60 or 70, as well as a decent flow rate. Then, to chop or impale a quadrant, switch to your highest vacuum. You can turn the vacuum up, get the fragments, and then turn vacuum down to a point where it will not grip things as much. With epinucleus removal, I turn the vacuum to 200 or so and turn flow up to compensate. In that situation, you want followability, but you also want to minimize a post-occlusion surge. That's a stepwise paradigm I use for safety. I grab a dense nucleus, but grip is not important for the softer epinucleus. Let's say you have a new machine and you want to see how high of a vacuum you can use. Take a little fragment and hold it with a phaco tip. Let the vacuum build, then let it clear and see how much surge you get. If you do not get any, turn it up higher until you see jump- ing in the chamber. This gives you an idea of the high vacuum setting. For a case such as a soft lens, I will do hydrodelineation to separate the endonucleus from the epinucle- us. There is minimal hydrodissec- tion. Using irrigation and aspiration in foot pedal position 2, I will clear out a space, removing the OVD, anterior cortex and the anterior epinucleus. I will go to an epinuclear setting but use linear aspiration as opposed to panel aspiration. Resi- dents find that removing a soft lens that draws the epinucleus to the phaco tip. On the other hand, the problem with too much vacuum is surge, which is a dangerous possibil- ity. One thing to help prevent this is an anti-surge algorithm. Surge is very much dependent on the level of vacuum immediately before oc- clusion is broken. You have your tip, and your tip is occluded with the piece. If you have a vacuum of 200 and that piece suddenly goes in, that is where you will want to minimize surge. At different points during the case, such as when you need to impale the nucleus early on with chopping, high vacuum is very safe. You can turn it up to 500 because if you get a little surge, there will not be any issues with the posterior capsule. If you want to work on the epinucleus or the last fragment, you will want to use a much lower vacu- um, perhaps 200. At that point, grip is more challenging than working with harder nuclei. They tend to overuse phaco and can actually phaco right through these soft nuclei. I prefer linear control of aspiration in the epinuclear setting. Avoiding wound burn is always an issue, and the risk for wound burn can increase with smaller in- cisions. That said, 2.2 mm incisions are common nowadays. It's critical to make sure there is flow under the OVD on top of the lens and to stay in foot position 2 while removing the anterior cortex and epinucleus. Surgeons should remain in foot position 2 for these tasks before going to foot position 3. Dr. Cohen is the Sterling A. Barrett Distinguished Professor, Department of Ophthalmology, University of North Carolina at Chapel Hill. He can be contacted at klc@med.unc.edu. 1. According to Dr. Henderson, which of the following is a goal of phacoemulsification fluidics? a. To maintain a stable anterior chamber b. To remove the cataract with minimal instrumentation c. To maximize heat production d. To avoid inducing dry eye 2. With a peristaltic pump, flow and vacuum must work together. a. True b. False 3. Which of these power modulations has more than 100 pulses per second? a. Burst b. Hyperburst c. Pulse d. Hyperpulse 4. According to Dr. Park, what kind of motion does traditional phacoemulsification use? a. Side to side b. Circular c. Forward and backward d. Pulsating 5. According to Dr. Cohen, what would be appropriate vacuum for sculpting? a. 30 to 40 b. 60 to 70 c. 100 to 120 d. 150 to 175 CME questions (Circle the correct answer) Copyright 2014 ASCRS Ophthalmic Corporation. All rights reserved. The views expressed here do not necessarily reflect those of the editor, editorial board, or the publisher, and in no way imply endorsement by EyeWorld or ASCRS. Using a phaco flow pump continued from page 66 To claim credit and take this test online, go to bit.ly/1zv6sQv or complete the test below and fax, mail, or email. To claim credit, please fax the test and fully completed form by January 31, 2015 to 703-547-8842, email to GPearson@ascrs.org, or mail to: EyeWorld, 4000 Legato Road, Suite 700, Fairfax, VA 22033, Attn: August 2014 CME Supplement ASCRS Member ID (optional): First/Last Name/Degree: Practice: Address: City, State, Zip, Country: Phone: Email: Please print email address legibly, as CME certificate will be emailed to the address provided. This CME supplement is supported by unrestricted educational grants from Alcon and Bausch + Lomb.

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