REFRACTIVE 20 EWAP SEPTEMBER 2023 did have to take off a significant amount of tissue to achieve the refractive correction, that could be a risk factor for ectasia even though you kept your residual stromal bed above 300,” he explained. This is where having a comprehensive refractive mindset comes into play. Dr. Chu said if a patient might not be the best candidate for LASIK due to a high refraction and a cornea that’s of low to low-normal thickness, the conversation can shift to other technologies that are now available. “This is not just LASIK anymore. We think more comprehensively across the continued on page 24 because the quality of the tears is important for quality of vision after any refractive surgery,” Dr. Chu said. If dry eye is identified and able to be addressed preoperatively, Dr. Chu said it might allow a patient to be a candidate for LASIK or another refractive procedure, like SMILE. In a presentation that Dr. Ambrosio sent to EyeWorld, he credited the range of advances in diagnostics that allow the surgeon to determine the best refractive procedure for each patient’s unique situation, as well as prevent complications in patients who might be at a higher risk. He also said in the presentation that it’s important to remember whether the procedure is refractive or therapeutic. “We have to understand each patient individually, their individual needs, and the current condition so that we set proper expectations if a patient needs a therapeutic procedure in which we use refractive technology,” Dr. Ambrosio said in the presentation, mentioning an editorial from 2013 in the Brazilian Journal of Ophthalmology. 3 “It’s imperative when we talk about the goals of a patient who needs a therapeutic procedure, [it is] to improve the corrected vision. Elective refractive surgery aims to improve uncorrected vision. Properly setting expectations and goals will clearly define what success is.” From a surgical perspective, Dr. Chu said the biggest advancements have been new surgical procedures becoming available, like SMILE, the EVO ICL (STAAR Surgical), and advanced technology IOLs. Dr. Chu also said that intraoperative guidance systems are a newer piece of equipment that has allowed surgeons to treat astigmatism with lens-based solutions more accurately. In terms of laser vision correction like LASIK, Dr. Chu said that there have been improvements in ablation profiles over the years that create smoother transitions across the eye. “The smoother the transition, the smoother the ablation, the less regression, the less enhancements, and the more accurate the procedure,” he said. There’s also been improvements in understanding the importance of residual stromal bed and the impact of percent tissue altered over the years. “There is some general consensus now that residual stromal bed should be about 300 microns and over for LASIK patients. But it also depends on the percent tissue altered, which means if the residual stromal bed is 300 and over but you Figure 2. Scheimpflug tomography; irregular astigmatism has a similar pattern as in Figure 1; the thickness map indicates thickening in the steeper zone, which does not resemble an ectatic pattern. Source: Renato Ambrosio, Jr., MD, PhD
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