Eyeworld

I OCTOBER 2019 | EYEWORLD | 47 eyes" and introduced artificial intelligence "to improve performance and harness the power of machine learning." Astigmatism control Astigmatism control can spell the difference between a satisfied and an unsatisfied patient. Surgeons can opt for either relaxing incisions or a toric IOL. "LRIs can be successfully used for low amounts of astigmatism. In our practice, we sometimes use femtosecond laser-assisted AKs for small amounts of astigmatism," Dr. Hill said. "However, we prefer toric IOL placement for ATR astigmatism of 0.50 D or more and WTR astigmatism of 1.00 D or more." Generally, Dr. Raviv prefers toric IOLs. "Studies that compare relaxing incisions to toric IOLs show a greater accuracy and stability to the toric IOLs," 3,4 he said. "Therefore, we should use a toric IOL whenever we can. Of course, in the U.S. the lowest power toric IOL is either 1.25 D (Envista and Trulign Toric released in the future, will add lens thickness, white-to-white and the central corneal thickness as input parameters. I anticipate that the calcu- lation range for version 3.0 will be the same as for version 2.0." The Hill-RBF artificial intelligence calcula- tor is licensed to Haag-Streit and optimized for use with the LENSTAR LS 900. Dr. Koch recommends these formulas but makes allowances for surgeon experience. "I think that ophthalmologists should use formulas that they have optimized with their experience, if they have tracked their outcomes, plus one or more of the newer or more sophis- ticated formulas: Barrett Universal II, Hill-RBF, Holladay 2, and Olsen," he said. "These latter [four] are typically going to outperform older formulas in eyes at the extremes: short/long axial length, shallow anterior chamber, unusual corneal power." Dr. Raviv cited the Ladas Super Formula (LSF) as "promising, but more data is forth- coming." Initially developed by John Ladas, MD, the current iteration, according to the web- site (iolcalc.com), improves on the original LSF "using two major studies of more than 4,000 About the doctors Warren Hill, MD Medical director East Valley Ophthalmology Mesa, Arizona Douglas Koch, MD Professor and Allen, Mosbacher, and Law Chair in Ophthalmology Cullen Eye Institute Baylor College of Medicine Houston Tal Raviv, MD Associate clinical professor of ophthalmology New York Eye & Ear Infirmary of Mount Sinai Icahn School of Medicine at Mount Sinai New York continued on page 48 Dr. Koch said the choice between an LRI or toric IOL depends on a surgeon's "comfort level with both technologies." LRIs (above) can be successful for low amounts of astigmatism, Dr. Hill said, but toric IOLs are preferred for 0.5 D or more of ATR astigmatism and 1 D or more of WTR. Source: Rex Hamilton, MD

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