Eyeworld

Reporting from the 2016 ESCRS Congress, September 10–14, Copenhagen, Denmark EW MEETING REPORTER 150 Douglas Koch, MD, Houston, spoke about measuring astigma- tism. First, he questioned "What is the threshold for correction?" For monofocal IOLs, Dr. Koch said it could be anywhere from 0.5 to 0.75 D, but "multifocal IOLs are a dif- ferent story," he said. You need less than 0.5 D. "It doesn't take much to disrupt the optical system of a multi- focal IOL," he said. Dr. Koch stressed the impor- tance of figuring out your own re- sults. Optimize your lens constants, he said, because patients will not see the benefit if the sphere is off. He also said to double check your mea- surements. Knowing the surgically induced astigmatism is critical. Examining at least three data points is key, Dr. Koch said, referenc- ing optical biometry for power, to- pography for alignment, and glasses. "If you have discrepancies in your measurements, remeasure," he said. To measure the anterior cornea, topography becomes important. Dr. Koch described using both reflection devices and elevation-based devices. Factoring in the posterior corneal astigmatism and being particularly aware of tough eyes were also important points that Dr. Koch discussed, concluding with the importance of being skeptical. Controversies in cataract and refractive surgery The Journal of Cataract and Refractive Surgery's symposium presented a series of controversies in the field. Dan Reinstein, MD, London, Julian Stevens, MD, London, and Erik Mertens, MD, Antwerp, Belgium, discussed the merits of small incision lenticule extraction (SMILE), femtosecond LASIK, and phakic IOLs, respectively. Each defended their procedure of choice for treating low to moderate myopia under 6 D. Dr. Reinstein, who performs SMILE on 77% of his refractive surgery patients, said patients might be attracted to SMILE as a flapless, keyhole procedure that allows them to return to work and daily activi- ties, including impact sports, right away. Dr. Reinstein presented data that suggests the safety and efficacy of newer SMILE techniques is similar to that of LASIK. He admitted that visual recovery is a bit slower, but said SMILE is able to reach refractive targets within 0.5 D 84% of the time. Advantages of SMILE over LASIK, according to Dr. Reinstein, include a biomechanical advantage from the cornea being left intact, quicker recovery of corneal sensation, predictable spherical ab- erration due to a larger optical zone, and potentially better retreatment options. As for the learning curve, which has been described as rather steep, Dr. Reinstein said he charted the curve of a surgeon learning SMILE and LASIK at the same time, and found SMILE was adopted faster. Next, Dr. Stevens lauded the well-established, long-standing ap- proval of LASIK, which over decades has improved in its technology, making it an even more accurate and customizable procedure. Dr. Stevens noted that LASIK results in more consistent outcomes in terms of predictability. SMILE, he said, presenting data from several studies, shows more variable efficacy data compared to LASIK, but he acknowledged that more refined nomograms could equalize the procedures. Dr. Stevens also discussed the microdistortions of Bowman's layer that can occur with SMILE, as well as diffuse lamellar keratitis, decen- tration, and ectasia. Dr. Steven's main argument in favor of LASIK over SMILE is that its biomechan- ical advantage is still scientifically unknown. He said once we are able to measure the stress-strain relationship at 70 µ depth incre- ments, "then we will know truly the absolute biomechanical advantage, disadvantage, or equivalence of the procedures." "Until then, it is a complete un- known," he continued. "Therefore, SMILE should remain, if you like, a very interesting investigational procedure, but LASIK is the bench- mark." Dr. Mertens said that while it is controversial, 92% of his refractive surgeries are phakic IOLs. Advan- tages include their removability, predictability and stability, quality of vision, leaving the cornea and crystalline lens intact, and leaving the possibility for better calculations of advanced technology IOLs in the future. Some might note the risk of endophthalmitis in this procedure, but Dr. Mertens cited research that found endophthalmitis in 0.0167% of 18,000 phakic IOL cases. The potential to induce early cataract is rarer than before. Dr. Mertens described the visual quality in phakic IOLs as being high definition and superior to the out- comes in LASIK and SMILE. October 2016 View videos from ESCRS 2016: EWrePlay.org Eric Donnenfeld, MD, discusses the use of a novel IOL for extended depth of focus.

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