Eyeworld

I CATARACT SURGERY POST-LVC with the standard Haigis formula. They found the combination to be as accurate as formulas that were specifically designed to be used in post-LASIK eyes. 1 "That said, the overall results still weren't stellar, so we still have a long way to go," he cautioned. "There is no one magical device that gives us a perfect measurement every time. At this point our best bet is to use all the biometers and see if they tend to agree," Dr. Devgan said. "Also, we must emphasize to patients that par- ticularly in a post-LASIK eye, we are doing IOL power estimations and not exact calculations." improved anterior and posterior corneal topographic measurements, combined with ray tracing," he said. To predict corneal power, "we have to rely on corneal topography, and we're hoping that eventually we'll get a meaningful posterior cor- nea measurement," he added. "I am cautiously encouraged by some data we have generated from the IOLMaster 700 [Carl Zeiss Meditec] that shows the total keratometry value could be an improved measure of corneal power com- pared to simply measuring the anterior cornea and guessing posterior corneal power." Dr. Koch cited their study in which they used total keratometry from the IOLMaster 700 About the doctors Zaina Al-Mohtaseb, MD Assistant professor of ophthalmology Baylor College of Medicine Houston Uday Devgan, MD Chief of ophthalmology Olive View UCLA Medical Center Los Angeles Damien Gatinel, MD Head of the Anterior Segment and Refractive Surgery Department Rothschild Foundation Paris, France Douglas Koch, MD Professor and Allen, Mosbacher, and Law Chair in Ophthalmology Cullen Eye Institute Baylor College of Medicine Houston continued on page 44 In the end, it may be that the complexity of IOL power calculations is such that the best option is to get help from computers. " We are in the age of artificial intelligence (AI) and we are now starting to see sophisticated algo- rithms that can improve accuracy in these post-re- fractive eyes," Dr. Devgan said. "I am working with John Ladas, MD, an ophthalmologist and a scientist with great expertise in this area. His novel AI-based approach to these post-refractive eyes shows a lot of promise and is in development with Advanced Euclidean Solutions and will soon be featured for free at www.IOLcalc.com." "The use of machine learning techniques can certainly bring new approaches to solve this issue," Dr. Gatinel said. Dr. Gatinel worked with Guillaume Debellemanière, MD, and Alain Saad, MD, to develop a new formula they call Precision Enhancement using Artificial Intelligence and Output Linearization (PEARL-DGS), accessible online at www.pearldgscalculator.com. "This formula is based on both optical and some kind of regression (machine learning based) considerations," he said. "I am not sure that pre- operative measurements (e.g., live OCT at the time of surgery to locate the capsular bag positioning) would help much unless you collect enough data to compensate for all the variability that happens to occur during surgery (intraocular pressure varia- tions, corneal edema, vitreous changes, etc.) and that may fool proper estimation of eye anatomical relevant dimensions and spaces. For these same results, intraoperative aberrometry did not really deliver what it initially promised." Domo arigato, Mr. Roboto AUGUST 2019 | EYEWORLD | 43

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