26 EyeWorld Asia Pacific | June 2024 Dr. Trattler says with use of the LASSO formula he has felt comfortable implanting ICLs in patients below the 3.0 mm, on-label ACD indication. Source: William Trattler, MD The top Pentacam image shows ACD (internal) with readings of 3.31 mm, while Dr. Barnes said an IOLMaster 700 measurement (not pictured) reported ACD as 3.84 mm. ACD (internal) from Pentacam (pictured bottom) in the other eye was 3.27 mm, while the IOLMaster measured 3.8 mm. Dr. Barnes said the average corneal thickness was about 0.5 mm (500 microns), which explains the discrepancy of ACD when measured from the endothelium vs. the epithelium. Source: Scott D. Barnes, MD Blake Williamson, MD, said his practice actually found out that it had been inputting data from the ACD exterior (measuring from the epithelium) instead of interior. Thankfully, he added, it didn’t have a clinical impact. “When you have a technology that’s as amazing as the EVO ICL, frankly, it makes up for a lot of minor things that you might be doing wrong because patients are seeing so well and because it’s so forgiving,” he said. “But even though it’s so forgiving and patients are going to be happy to ecstatic, it doesn’t forgive not being really careful with how you’re entering the data. So it’s important to have this conversation about how we enter the data accurately.” If you are using a device that measures from the epithelium, Dr. Barnes said to simply subtract the corneal thickness and use that number in your nomogram. He said the STAAR OCOS software displays a warning reminder to “please enter the true ACD” and defines this as measured from the endothelium,” and to subtract the corneal thickness if your instrument only measures ACD from the epithelium. Dr. Trattler said he has been using the LASSO formula that takes data from the IOLMaster 700 and the MS-39 anterior segment OCT (Costruzione Strumenti Oftalmici, CSO), which is input into an excel spreadsheet. The formula predicts the expected vaults for each different size ICL. With this formula, he said he has felt comfortable implanting a number of ICLs in patients who were below the 3.0, on-label ACD indication in the U.S. Dr. Trattler explained that the on-label ACD was the limit set for inclusion in the clinical trials to help make sure patients ended up with a normal vault. “Now that we have more data both within the U.S. and internationally, as well as more analysis of EVO ICL outcomes, we can use calculators to select ICLs that will have a normal vault, even if the ACD is below 3.0,” he said. Erik Mertens, MD, said internationally an ACD (endothelium to anterior capsule) of 2.8 mm for myopia and 3.0 mm for hyperopia is acceptable. He, however, finds “you can go lower than the ACD recommended by STAAR if the angle is wide open.” “Understanding the true ACD means investigating the morphology and width of the ciliary sulcus and the ciliary body,” Dr. Mertens continued. Dr. Mertens said in an email to EyeWorld he will consider ICL for patients who have smaller ACD measurements after a thorough discussion and, again, if the angles are wide open. REFRACTIVE SURGERY
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