CORNEA 26 EWAP DECEMBER 2022 by Liz Hillman Editorial Co-Director The role of corneal imaging for IOL planning Contact information Koch: dkoch@bcm.edu Miller: kmiller@g.ucla.edu Corneal imaging for IOL planning is vital, but what instruments to use and what the measurements from these different instruments inform varies. EyeWorld spoke with Douglas Koch, MD, and Kevin M. Miller, MD, to get their thoughts on corneal imaging as part of the preop planning process. What do you use? Every new patient in Dr. Koch’s practice gets a Galilei (Ziemer) image. Dr. Koch said this device, which features Placido topography and dual Scheimpflug tomography, gives him the opportunity to assess the anterior surface using the Placido mires. The tomography contributes corneal thickness data and if there is any evidence of ectasia. From there, if cataract surgery is scheduled, Dr. Koch said patients are prescribed an at-home treatment regimen of preservative-free tears, warm compresses, and lid scrubs before coming back for the preoperative visit with biometry readings. On the day of preop testing, two biometry readings are obtained, an IOLMaster 700 (Carl Zeiss Meditec) and a Lenstar (Haag-Streit). Dr. Koch said both of these contribute valuable corneal data. “We’re using other devices as well, but those are our mainstays. Patients get three different measurements but on two separate occasions,” Dr. Koch said. “You don’t have to use three different devices, but it’s nice to get at least two measurements, preferably with two different instruments and on separate days, so you get a sense if there are any ocular surface issues that are a concern.” Dr. Miller also uses a number of different instruments. When selecting the spherical power for a lens, his primary imaging modality is a standard biometer (the Lenstar LS900 or IOLMaster). If he’s doing astigmatism management, he also uses a topographer or tomographer. He has a Galilei but said his workhorse instrument is the Pentacam AXL Wave (Oculus). Dr. Koch said, in general, if you’re doing presbyopia- correcting IOLs, a tomography measurement should ideally be obtained to confirm a regular cornea that will provide the optical quality needed by the IOL. It also helps the surgeon know if a future enhancement could be possible. Considerations for quality images and analysis Dr. Miller said ophthalmologists are often reliant on technicians to ensure quality images and measurements are obtained. The surgeon then analyzes the data, seeing if it makes sense before using it in IOL planning. 1. Head positioning. “If the patient is too low or too high to the measurement axis or too far to the left or right, the topographer or tomographer is going to be centering its measurements on a different part of the cornea rather than the actual center of the This Pentacam AXL Wave tomography map is from a patient who underwent LASIK years earlier. The central cornea has been flattened about 8.5 D. One part of the ablation zone is flatter than the rest, indicating irregular astigmatism. This would be a poor candidate for a multifocal IOL, even if the lens power calculation was perfect. This article originally appeared in the September 2022 issue of EyeWorld. It has been slightly modified and appears here with permission from the ASCRS Ophthalmic Services Corp.
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