Eyeworld

50 | EYEWORLD | JULY 2023 R EFRACTIVE Contact Ambrosio: dr.renatoambrosio@gmail.com Chu: yrchu@chuvision.com References 1. Ambrosio R. Multimodal imaging for refractive surgery: Quo vadis? Indian J Ophthalmol. 2020;68:2647–2649. 2. Salomao MQ, et al. Role of the corneal epithelium measure- ments in keratorefractive surgery. Curr Opin Ophthalmol. 2017;28:326–336. 3. Ambrosio R. Therapeutic re- fractive surgery: why we should differentiate? Rev Bras Oftalmol. 2013;72:85–86. 4. Lopes BT, et al. Enhanced tomographic assessment to detect corneal ectasia based on artificial intelligence. Am J Ophthalmol. 2018;195:223–232. 5. Ambrosio R, et al. Integration of Scheimpflug-based corneal tomography and biomechanical assessments for enhancing ectasia detection. J Refract Surg. 2017;33:434–443. 6. Ambrosio R, et al. Optimized artificial intelligence for en- hanced ectasia detection using Scheimpflug-based corneal tomography and biomechan- ical data. Am J Ophthalmol. 2022;251:126–142. "We have to understand each patient indi- vidually, 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 Ophthal- mology. 3 "It's imperative when we talk about the goals of a patient who needs a therapeutic procedure, [it is] to improve the corrected vi- sion. 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 surgi- cal procedures becoming available, like SMILE, the EVO ICL (STAAR Surgical), and advanced technology IOLs. Dr. Chu also said that intraop- erative 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 im- provements 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 enhance- ments, and the more accurate the procedure," he said. There's also been improvements in under- standing 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 did have to take off a significant amount of tissue to achieve the refractive cor- rection, 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 con- versation can shift to other technologies that are now available. "This is not just LASIK anymore. We think more comprehensively across the five different procedures—PRK, LASIK, SMILE, ICL, and re- fractive lens exchange—for treating people," he said. "It's gotten more exciting, more complex." What's next? Dr. Chu said he'd like to see continued improvement in diagnostic screen- ing for refractive surgery candidacy. He said what he would like are pieces of equipment that integrate multiple tests into one device. He acknowledged some negatives to that (such as if the device breaks) but said it would greatly improve efficiency in the preoperative setting. Procedurally, Dr. Chu said that LASIK already works well, and other options in the market, such as SMILE and ICLs, could continue to see improvements. In his presentation, Dr. Ambrosio men- tioned the convergence of "applied artificial intelligence with ancient philosophy being im- portant for customized treatments and individu- alized medicine" going forward. He shared with EyeWorld examples of clinical studies on how artificial intelligence can enhance interpretation of Scheimpflug tomography, 4 and integrating it with corneal biomechanics, 4,5,6 to reduce the risk of ectasia after refractive surgery. continued from page 49 Preop diagnostic and screening technologies for refractive surgery Slit lamp biomicroscopy Central corneal thickness Placido topography Ocular surface imaging 3D Scheimpflug tomography Corneal total and internal wavefront imaging Ocular scatter imaging Ocular biometry Segmental tomography IOP/corneal biomechanic measurements Specular/confocal microscopy Osmolarity, molecular biology, and genetic testing Source: Renato Ambrosio Jr., MD, PhD

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