Eyeworld

68 | EYEWORLD | SPRING 2026 R EFRACTIVE corneal tomography or corneal thickness. One should have a very low threshold for evaluating the mires of the biometer LEDs if the measure- ments don't add up." If you don't have multiple devices, Dr. Koch said he and his colleague Li Wang, MD, PhD, developed a formula with Zeiss to help provide central topographic information from IOLMaster 700 measurements, but he noted this is only the central 3–3.5 mm. "Ideally, you want a topography/tomog- raphy and LEDs. Let's say you have a patient come in, you get a topography, tomography, and maybe on that first visit, if you only have one bi- ometer, get a Lenstar or an IOLMaster 700, then when they come in for the preop visit, repeat the biometry. If it's consistent with a prior mea- surement, you're in good shape. If it's not, then you have to check the surface," Dr. Koch said. Dr. Koch added that if he only had one biometer and one topographer, taking two mea- surements from each and finding that measure- ments were consistent with the biometer but different with the topographer, he would rely on the biometer "because those LED measure- ments are usually very good." There is a caveat, however. "You need to look at the raw data … the little black dots that are in the printout of the IOLMaster 700, or you can look at the Lenstar device where it shows you what the LED reflections look like. You should verify that these are not smudged—or worse, absent." Dr. Fram said she has two biometers in her practice from which she obtains measurements on the same day. She noted that biometry reli- ability of K readings is getting better and better. "With IOLMaster 700 with Total K, then Lenstar and Argos [Alcon], I think we're seeing a lot of improvement in our K values," she said. After biometry, Dr. Fram also emphasized the utility of topography with Placido imaging is critical. "This can give you a snapshot of the tear film quality." She said there are different modalities that are allowing physicians to look at the K values. Dr. Fram finds Pentacam (Ocu- lus) with dual Scheimpflug imaging helpful, but it does not give Placido imaging and has lim- itations in isolation. iTrace ray tracing (Tracey Technologies) is helpful to look at higher order aberration profiles and has Placido imaging. "Anterior OCT imaging has an anterior axial cur- vature map—3D surface fit generated from 65 radial OCT scans with 16,640 data points over 8 mm. It will also give total corneal power. Fi- nally, something as simple as reviewing patients' refraction in glasses before cataract develop- ment can help guide the surgeon when there is a discrepancy in testing," she said. "We want to see at least three of these measurements line up for magnitude and me- ridian," Dr. Fram continued. "When you have all of these measurements line up, it's a home run. When you have three out of the five, you're still doing pretty well. But you have to figure out in your clinic, what are the three most reliable diagnostics that are going to determine whether you treat astigmatism." Dr. Fram said to feel confident in her measurements she needs to see regular Placido imaging on her topographer and quality mea- surements with good fixation from her biome- ters. "Whenever I skip a step, that's when bad things happen. So, I have a very low threshold for bringing someone back before surgery," she said. "I had a patient who I thought looked OK at first glance, but when I was going over my charts the night before, I had no problem calling the patient and saying, 'I need you to come back in the morning ahead of your surgery to double check.' … I never hesitate to bring patients back in for a remeasurement, and sometimes I treat the ocular surface before I bring them back." Dr. Fram acknowledged that she has many technologies to take measurements. If you don't have redundancies among devices, astigmatism can still be accurately measured and treated. "You may want to bring patients back on two different days if you have the same technolo- gy. If you have multiple technologies that are redundant and do the same thing, you can do it all at once. If you have one biometer and one topographer, it's not a bad idea to bring patients back for another measurement if they're not in complete alignment," she said. "If you have multiple devices and the readings are all dif- ferent on each device, there must be an ocular surface or user variability issue going on." Ocular surface evaluations and management The ocular surface is often the cause of incon- sistent K measurements, both Dr. Fram and Dr. Koch said. Dr. Koch said if you find different measure- ments, it's time to look at the surface for punc- tate erosions, rapid tear film breakup, dry eye, continued from page 66

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