Eyeworld

68 | EYEWORLD | MARCH 2020 I ILLUMINATING INTRAOPERATIVE TECHNOLOGIES N FOCUS Contact Berdahl: john.berdahl@ vancethompsonvision.com Henderson: bahenderson@eyeboston.com Koch: dkoch@bcm.edu Refining your use for better results If you're using aberrometry, keep in mind that there are a few factors that can adversely alter the readings. These include: • The lid speculum • Trauma to the epithelium • Corneal edema • Not filling the eye with the appropriate oph- thalmic viscosurgical device (OVD) • A dry corneal surface • Poor patient focusing • A low or high IOP • The wrong input of preop data • Scars To help avoid these factors and to improve your aberrometry results, here are a few clinical pearls: 1. Protect the corneal epithelium. Start as soon as the patient is in the ASC and until the time of measurement, Dr. Koch advised. 2. Keep the cornea protected with OVD or with frequent irrigation. A cohesive OVD should be used to fill the eye rather than a dispersive OVD or a hybrid OVD with a high molecular weight, Dr. Henderson said. 3. Make sure the patient is looking directly at the fixation light. Ask him or her to tell you when that light goes out. "That helps guarantee that they are looking in the correct direction," Dr. Koch said. 4. Use the personalized outcomes to help guide decisions. Dr. Berdahl finds the numbers that are particular to his surgical outcomes more useful than global outcomes. "With time, you get a sense of when you should trust [the numbers] more and when you shouldn't," he said. Calculation changes Just how often does the use of aberrometry change the IOLs that surgeons might use? For Dr. Berdahl, it will change his choice of a toric lens about 30% of the time. In post-re- fractive cases, it changes his decision about 20–30% of the time. For standard eyes with no special needs or pathology, it only changes his choice about 5% of the time; these are not eyes that typically benefit from aberrometry, Dr. Berdahl added. For Dr. Koch, the use of aberrometry changes his choice in post-LASIK eyes about 25% of the time. However, he pointed out that he and his colleagues do a lot of research on preop measurements, so he has two biometers used before surgery. Additionally, they do many more preop calculations, beyond what other surgeons typically do. Considering the latest IOL formulas Despite these potential benefits from using intraoperative aberrometry, there still is the question of its value when there are newer IOL power calculation formulas, such as the Hill- RBF and Barrett Universal II formulas, known for their high level of accuracy. "As these formulas have improved, there's less of a benefit to intraoperative aberrometry in standard cases, but the benefit is still mean- ingful in toric lenses and post-refractive cases," Dr. Berdahl said. "As good as these newer formulas are, intraoperative aberrometry is still better than an IOL formula alone," Dr. Henderson said, adding that the change in IOL power made by many surgeons using intraoperative aberrometry has led to an improvement in their outcomes. Dr. Koch thinks the role of aberrometry will diminish as formulas continue to improve, but the end result is situation- and surgeon-spe- cific. "It depends on how many measurements a surgeon gets. If it's just one biometer mea- surement, then [the results] from intraoperative aberrometry could be a lifesaver," he said. continued from page 67 About the doctors John Berdahl, MD Vance Thompson Vision Sioux Falls, South Dakota Bonnie Henderson, MD Clinical professor Tufts University School of Medicine Boston, Massachusetts Douglas Koch, MD Professor and Allen, Mosbacher, and Law Chair in Ophthalmology Baylor College of Medicine Houston, Texas Relevant disclosures Berdahl: Alcon Henderson: Alcon Koch: Alcon, Carl Zeiss Meditec, Johnson & Johnson Vision

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