20 EyeWorld Asia Pacific | June 2024 There has been controversy around ICL sizing and vault for a long time, said Mark Packer, MD. Even since 20 years ago, there were proponents of using ultrasound to look at the distance across the sulcus, which is where the lens is going to go, and saying that is really more appropriate compared to using surrogate measures of corneal whiteto-white and anterior chamber depth, which are the key elements in the approved nomogram that STAAR has in their labeling. The EVO ICL (STAAR Surgical) comes in four sizes: small (12.1 mm), medium (12.6 mm), large (13.2 mm), and XL (13.7 mm), Dr. Packer said. “I think one of the other interesting things we learned in the clinical trial is people tend to want to avoid extra-large.” People tend to want to avoid the extremes, because they are wary of high and low vault, he said. However, in the clinical trial, the highest vault was not with a 13.7 lens; it was with a 13.2 lens, Dr. Packer added. Neda Nikpoor, MD, said the size of the EVO is decided during preoperative testing. In addition to typical refractive screening tests, Dr. Nikpoor also uses IOLMaster (Carl Zeiss Meditec), Pentacam (Oculus), a digital caliper for primary white-to-white measurement, and UBM (Sonomed). She will also do a contact lens over refraction for high myopes. Dr. Nikpoor uses the Dougherty nomogram for UBM to measure sulcus to sulcus. “I find that tells me a lot more than just ‘white-to-white,’ she said. “I look at white-toby Ellen Stodola, Editorial Co-Director Taking A Closer Look At ICL Sizing and Vault Concerns white and see where that lands on a modified nomogram.” If the white-to-white is on the border between two sizes, then I favor whatever the UBM is going to tell me and let that be a tiebreaker. If they disagree completely, I’ll still use the UBM with a little bit of caution, she said. “I’m looking at the sulcus and where it will sit.” As another tie breaker, I will look at lens rise on the UBM, and if it’s more than 0.75, then I would favor sizing up, Dr. Nikpoor added. If whiteto-white and sulcus-to-sulcus are very much in the middle of the size range and lens rise is over 0.75, Dr. Nikpoor won’t change from the recommended lens, using those two nomograms that agree. She uses lens rise as a tiebreaker or third data point. The other important data point, she said, is anterior chamber depth (ACD). It is CE marked down to 2.8 in Europe, so Dr. Nikpoor will often go down to 2.8 or even 2.75. “If I have someone who has less than a 3-mm ACD, if the sizing looks like it’s going to be tight, I’ll downsize because I’d rather have a lower vault and a shallower anterior chamber depth,” she said. “If I have something that’s really borderline between two sizes and have a 3.5 anterior chamber depth, I’m more comfortable bumping up a size.” If she’s between two sizes, in a normal 3–3.2 ACD with everything else average, she tends to size down. The rate of cataracts with EVO is very low, Dr. Nikpoor said, lower than it was with Visian (STAAR Surgical). “I was a lot more willing to size up with Visian, but now we have REFRACTIVE SURGERY
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