Eyeworld

7 Supported by Abbott Medical Optics Inc., Alcon Laboratories Inc., and AcuFocus 7 Meticulous preoperative planning and surgical strategies can help ophthalmologists optimize visual quality when correcting presbyopia P erhaps surprisingly, most ophthalmic surgeons achieve refractive out- comes within 0.5 D of their target refraction in only 60–70% of their pseudopha- kic presbyopia-correcting proce- dures. The good news is they can take their results much higher, said Douglas Koch, MD, professor and Allen, Mosbacher and Law chair in ophthalmology, Cullen Eye Institute, Baylor College of Medicine, Houston. The 2015 ASCRS Clinical Sur- vey showed that 62% of respon- dents think 0.75 D of astigmatism is acceptable (Figure 5), and 41% think 0.75 D of spherical error is acceptable. However, Dr. Koch has higher aspirations. "We really want to be at 90% and above," he said. There are a number of ways that surgeons can lower their thresholds for acceptable refrac- tive error levels after presby- opia-correcting surgery, Dr. Koch said. Strategies to raise the bar in presbyopic correction: An interview with Douglas Koch, MD Increased accuracy "You have to become very ac- curate to become the surgeon that people want to go to—not only for cataract surgery but for refractive lens exchange," he said. Not only do surgeons need to establish preoperative and postop- erative strategies, but they need to know how to manage postopera- tive refractive errors using various options. "These may include relaxing incisions, laser corneal surgery, or in some instances, even IOL exchange," he said. During preoperative plan- ning, he suggests obtaining 2 or 3 measurements from different devices, including a biometer and topographer. If a significant dis- crepancy is found, the measure- ments should be repeated. "Part of that whole process is looking at the ocular surface when a patient first presents," Dr. Koch said. "We look at the mires of the Placido topographer, and if the mires are not pristine, then we go ahead and treat the patient with artificial tears, at a mini- mum, and bring them back to remeasure them," he said. He prefers the LENSTAR Optical Biometer (Haag-Stre- it) and IOLMaster 700 (Carl Zeiss Meditec) as his automated keratometers for astigmatism planning. His favorite formulas are the Holladay 1, the Barrett Univer- sal II formula, and Warren Hill, MD's new RBF formula. For long eyes, Dr. Koch still gets the best accuracy with the Holladay 1 with the Wang-Koch axial length mod- ification. For short eyes, he adds the Olsen formula to the other 3 and looks for an average of the 4 calculated values. The simplest solution to de- termine the posterior astigmatism is Barrett's formula, he said, but he still relies heavily on the Bay- lor nomogram. "In addition, Adi Abulafia, MD, and I have devel- oped another formula, and I now use this routinely; some manu- facturers are going to incorporate that into their toric calculators," Dr. Koch said. The literature has not shown that any device can accurately measure posterior corneal astigma- tism on a patient-by-patient basis, but Scheimpflug devices and LED reflection technology are bringing surgeons closer to that point, Dr. Koch said. Researchers also are investigating optical coherence to- mography to determine posterior corneal astigmatism. "The idea would be to have a technology in our hands some- time in the next year or 2 that would give us true corneal power measurements, both in terms of front and back power and also front and back astigmatism, and I think that we would see a huge step up in the accuracy of our lens calculations," he said. Surgical options Dr. Koch thinks surgeons can achieve successful outcomes without a femtosecond laser. "I think we are still looking for clear data that show there might be an advantage in terms of refractive surgery," he said. "I think that will come as these lasers become more refined and as we develop lens implants that might more clearly attach to the anterior capsule so the precision of the capsulotomy might be critical." Additionally, Dr. Koch thinks the literature has not demonstrat- ed greater benefits in creating relaxing incisions with the femtosecond laser compared with diamond knife incisions. "But I have no doubt that over time, as we refine it, this will take place," he said. Conclusion To optimize outcomes from presbyopia-correcting surgery, sur- geons need to master precise plan- ning and surgical techniques and successfully manage postoperative refractive errors. "It requires a broad skill set so that you can take good care of your patients from inception to the final outcome," Dr. Koch said. Dr. Koch can be contacted at dkoch@bcm.edu. Figure 5. Results of the ASCRS Clinical Survey regarding residual astigmatism after implantation of a presbyopia-correcting IOL Average All 0.7 U.S. 0.7 Non U.S. 0.8 Douglas Koch, MD

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