Eyeworld

81 EW REFRACTIVE March 2019 times helps me identify an outlier. In those situations, I find that if I use aberrometry and nudge the IOL calculation in that direction, it can be helpful. That said, some surgeons find aberrometry to be invaluable," he said. Dr. Koch thinks that aberrom- etry might gradually be replaced. "Our preoperative measurements will continue to improve, as will the formulas, and there will always be the limitation of aberrometry that the eye is modified by the time you're doing those measurements. The cornea's been doused with all kinds of drops and fluid, and there may be some edema," he said. The future Dr. Koch is interested to see how much further surgeons can go with their accuracy. "The current stum- bling blocks for the best calculations are effective lens position and cor- neal power. There are new devices for measuring posterior corneal power, but that's still evolving and not as accurate as we might want. Considering all the sources of error, we are going to be lucky if we hit 90% within 0.5 D. In terms of new technology, I'm intrigued by the concept of looking at intraoperative OCT and using that to help mod- ify the formula for effective lens position, but that's an expensive and time-consuming way to do calcula- tions. I would hope that we could find some equivalent of that in the preoperative measurement as well. However, even if that comes to frui- tion, the IOL position shifts in some eyes postoperatively," he said. EW Editors' note: Dr. Berdahl has finan- cial interests with Alcon (Fort Worth, Texas). Dr. Koch has financial inter- ests with Alcon, Carl Zeiss Meditec, Johnson & Johnson Vision, and Perfect Lens (Irvine, California). Dr. Lee has no financial interests related to his comments. Contact information Berdahl: john.berdahl@vancethompsonvision.com Koch: dkoch@bcm.tmc.edu Lee: bryan@bryanlee.pro If we make adjustments to the lens at the time of surgery, it's primarily because of aberrometry." For a starting point, Dr. Lee uses the User Group for Laser Interfer- ence Biometry (ULIB), which is an online database of other surgeons' outcomes that helps to generate A-constants that are more accurate than the manufacturers' lens con- stant. "At the same time, it's still im- portant to do your own analysis of your outcomes because the individ- ual surgeon may be different from the pool of the data. It is important to analyze your outcomes because, for instance, the ZCB00 IOL [John- son & Johnson Vision, Santa Ana, California] is listed as having an IOL constant of 119.3, but for me, it's more like 119.5. That ends up mak- ing a difference cumulatively. It's important to track your outcomes," he said. Intraoperative aberrometry Dr. Berdahl only uses intraoperative aberrometry in two situations: for patients who desire spectacle inde- pendence and in extreme situations, such as those eyes that are not in the middle of the bell curve and for which additional data points are needed to improve the outcome. Dr. Berdahl noted that aber- rometry is important in his decision of which implant power to use. "There are three scenarios: virgin eyes, those requiring toric lenses, and post-refractive eyes. With the advent of the Hill-RBF, we are rarely changing the spherical power in a virgin eye. It's probably less than 5% of the time now. When implanting toric lenses, I used to change the power or the orientation about 50% of the time, and it's about 33% of the time now because of Barrett's good work on his astigmatism toric planner. On post-refractive eyes, I'm changing it 25–30% of the time. I think that aberrometry still plays a critical role in decreasing enhance- ment rates for us, especially in toric patients," he said. Dr. Koch added that his practice looked in-depth at their data and found that using aberrometry did not help them. "In fact, had we not used aberrometry, we would have had slightly better results. However, even though it doesn't make me more accurate, aberrometry some- I N S T R U M E N T S | S I N G L E U S E | D R Y E Y E | B I O L O G I C S © 2018 Stephens Instruments. All rights reserved. Stephens Instruments | 2500 Sandersville Rd | Lexington KY 40511 USA Toll Free ( USA ) 800.354.7848 | info@stephensinst.com | stephensinst.com SAVE TIME & MONEY Removes hidden costs of time and resources spent on cleaning, sterilization, repair and replacement. REDUCE RISK Reduces risk of cross contamination. Overall improved patient safety. FRESH & PRECISE Each procedure begins with a new, precise and sterile SafeSite™ instrument. ! Look to Stephens for single-use instruments. SafeSite ™ Sterile Single-Use Instruments $

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