complexities of intraocular lens (IOL) power calculations while approaching and overcoming a variety of challenging patient situations. Oliver Findl, MBA, FEBO, Austria, began the MasterClass by presenting on cornea topography in IOL power selection. In patients with significant higher-order aberration (HOA), Dr. Findl suggested avoiding trifocal, extended depth of focus, and toric intraocular lens. Furthermore, if applicable, the practitioner should remove any superficial corneal pathology (pterygium, Salzmann nodules, or map-dot-finger dystrophy, for example) before operation. In dry eye patients, practitioners should use artificial tears before keratometry. “Ideally, you should put the eye drops in, wait for five minutes, and then take the keratometry measurement,” Dr. Findl said. With this technique, measurements are more accurate compared to taking a measurement 30 seconds after instilling lubricating eye drops. Yeo Tun Kuan, MBBS, MMed, Singapore, continued the discussion by providing recommendations on toric IOL power calculations. By utilizing three different machine astigmatism measurements, one can achieve more accurate outcomes while machine selection is less of an issue. The three readings may come from two optical biometers (IOLMaster and Lenstar) and one topographer, providing an integrated K value for toric IOLs. IOL power calculations can be even more complex when thinking about the sources of error. Youngsub Eom, MD, PhD, South Korea, provided the audience with four main reasons why calculated IOL power may not be as accurate as practitioners hope. Contributing factors include an inaccurate measurement area of the keratometer, the assumption that the posterior and/or anterior corneal curvature radii ratio is constant when calculating corneal power, an inaccurate estimation of effective lens position, and an inaccurate measurement of axial length. “How you want to treat the patient depends on how well the patient wants to see, whether that is near vision or distance vision,” said Fam Han Bor, MBBS, MMed, Singapore. In his presentation, Dr. Fam noted that it is important to distinguish whether patients desire sharp vision or comfortable vision. When practitioners target refraction in surgery, they must consider acuity needs, the target refraction, and the comfort of monovision. “All of this hinges on IOL power calculation,” says Dr. Fam. In fact, the field of calculating the power of IOLs is the perfect subject of study to apply the scientific method in medicine. The performance of measurements, the construction of anatomical and predictive models, predictions, and error measurements must be taken into consideration. Damien Gatinel, MD, PhD, France, with the help of his colleagues, created the PEARL-DGS formula (available at www.iolsolver.com) by taking into account multiple paradigms for predicting IOL power. The PEARL-DGS formula has been utilized by Dr. Gatinel to improve postoperative refractive outcomes in many patients. With keratoconus, IOL power calculation becomes a bit more complicated as well. Graham Barrett, MB BCh, FRACO, FRACS, Australia, described how keratoconus can present with steep K values. In addition, abnormalities of the cornea in patients with keratoconus disrupt the relationship of the posterior and anterior corneal radii, resulting in unexpected spherical outcomes. Through case presentations, Dr. Barrett suggested that the idea in solving the issue of keratoconus in calculating a correct power value is to provide a solution in which one formula will allow you to choose, among many, a piggy-back IOL prediction, a lens exchange prediction, a way to rotate the existing lens, and an effective lens position (ELP) option for prediction of IOL power. MasterClass: Mastering Toric IOLs In the 2022 APACRS MasterClass on “Mastering Toric IOLs,” Tetsuro Oshika, MD, PhD, Japan, discussed “Preoperative Consideration and Postoperative Management.” Dr. Oshika said that of all their patients undergoing cataract surgery, they found that 53% had greater than 0.75 D and 38% had greater than 1.0 D of astigmatism, indicating that many are good candidates for toric lens implantation. Residual astigmatism, he said, significantly deteriorates postoperative uncorrected distance visual acuity (UDVA). Reviewing the definitions of with-the-rule (WTR), against-the-rule (ATR), and oblique astigmatism, he said they’ve found that in terms of impact on vision, ATR had the greatest and WTR the least. In addition, the effect of toric IOLs reduced significantly over time in cases with preop ATR astigmatism but not in cases with preop WTR. Furthermore, he noted the importance of complete CCC-edge coverage of the optic; should rotation occur, repositioning should be delayed until rotation has stabilized at about 1 week. Using a yellow and blue color EWAP meeting reporter banner.indd 1 27/07/2022 10:22 AM
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