EyeWorld India March 2017 Issue

March 2017 10 EWAP FEATURE Experts provide their thoughts on how to get as close to target as possible “ T he measure of how good a surgeon is at selecting the correct IOL power is what percentage of cases are within ±0.5 D of the target,” said Jack Holladay, MD , clinical professor of ophthalmology, Baylor College of Medicine, Houston. And yet, research has shown that many surgeons are not achieving that goal. Data analysis from Massachusetts Eye and Ear Infirmary published in 2014, for example, showed that out of 1,275 surgeries, 67% were within ±0.5 D of the target refraction; 94% were within ±1 D. 1 Dr. Holladay said an “A surgeon” gets within ±0.5 D 90% of the time, which he thinks is less than 1% of surgeons. B surgeons— Perfecting IOL power predictions by Liz Hillman EyeWorld Staff Writer AT A GLANCE • Getting within ±0.5 D of target refraction is the goal, but there are still many surgeons not reaching that in their IOL calculations. • Personalizing or optimizing one’s lens constant improves accuracy of calculations. • Using an optical biometer instead of a contact A-scan can improve measurements for better calculations as well. • Avoid using drops or measuring IOP before performing keratometry as this can lead to variability in measurements. about 20% of today’s surgeons— get 80 to 90% of their cases within ±0.5 D, Dr. Holladay said. So how can an ophthalmologist improve the accuracy of his or her IOL calculations? The first tip recommended by Dr. Holladay and Kenneth J. Hoffer, MD , clinical professor of ophthalmology, Stein Eye Institute, University of California, Los Angeles, is to personalize their lens constants. “To be an A or B surgeon, you must personalize your lens constant by putting postop refractions into a software package,” Dr. Holladay said. “Most doctors don’t personalize; if they did, their results would improve dramatically,” Dr. Hoffer said. “Dr. Holladay and I were in a session [at a meeting] and he asked how many people personalize, and there were only two or three hands raised out of 50 to 70 people.” Dr. Hoffer gave an example of how optimizing one’s lens constant could affect patient outcomes. Let’s say you’re using the Hoffer Q formula and start out with a personal anterior chamber depth (pACD) of 5.55. After conducting 100 cases, inputting the implanted IOL lens power and the patient’s postop refraction into your optical biometer, it calculates the ideal anterior chamber depth for each patient. Taking an average of what they should have been, now the optical biometer is predicting that your pACD is 5.63. “Now you’re going to be using a more accurate pACD for the way you do surgery,” Dr. Hoffer said. At the same time, the calculations were also done for the surgeon factor (SF) for the Holladay 1 formula and the A constant for the SRK/T formula. If personalizing in this way can improve lens power calculation accuracy so much, why don’t more surgeons do it? Dr. Hoffer said it’s a matter of being consistent with your IOL selection and making a habit of going back 1 to 3 months postop to input the patient’s IOL power and refraction data. He added that some surgeons are not convinced of the importance of personalizing. Dr. Hoffer also recommended avoiding contact A-scan to determine the length of the eye. “Using a contact A-scan is the