Eyeworld

EW REFRACTIVE 42 July 2017 by Michelle Stephenson EyeWorld Contributing Writer Both provide good outcomes with minimal induction of higher order aberrations W avefront-guided and wavefront-optimized laser treatments offer advantages over tra- ditional laser treat- ments. In the past, many patients had night vision complaints after traditional LASIK. These complaints are rare with the more advanced algorithms. "Wavefront-guided and wave- front-optimized are two different algorithms for trying to provide the best quality vision to patients desiring laser vision correction with LASIK and PRK," said William Trattler, MD, Miami. Michael Greenwood, MD, Fargo, North Dakota, agreed. "Wave- front-guided and wavefront-opti- mized are great treatment options in many patients. Wavefront-guided will reduce pre-existing higher order aberrations, while wavefront-opti- mized will minimize the induction of new higher order aberrations. Both are superior to conventional treatments, which are more likely to induce higher order aberrations fol- lowing refractive surgery," he said. Wavefront-guided According to Dr. Trattler, wave- front-guided treatments use mea- surements of each patient's unique optical pathway to design a treat- ment that will correct the patient's refractive error, including any mild irregularities in the optical pathway. "It's taking an individualized scan of each eye, and the software develops a customized treatment based on the patient's unique findings," he explained. change with pupil diameter, they change with accommodation, and they change with age. I think most people in the United States, other than those using a VISX platform [Johnson & Johnson Vision, Santa Ana, California], do not use wave- front-guided. Surgeons using a WaveLight laser [Alcon, Fort Worth, Texas] typically do not use wave- front-guided treatments as the initial treatment, particularly now that we've got topography-guided," Dr. Gordon said. Wavefront-optimized According to Dr. Gordon, wavefront- optimized treatment, historically, was developed because surgeons realized that when energy was deliv- ered to the periphery of the cornea, particularly with the scanning spot laser, some energy was lost. "One reason for this is the cosine effect: Because we're coming tangential to the cornea, a certain percent- age of the energy is reflected and not absorbed. Second, because the Wavefront-guided vs. wavefront-optimized laser treatments C ompared to refractive surgery 15 years ago, modern day refractive surgery has evolved into a spe- cialty that utilizes advanced diagnostics to determine which technology is best for each situation. The most common refractive surgery procedures involve corneal laser vision correction or lens replacement. The technology choices in laser vision correction have grown significantly, much like our choices in lens replacement implant tech- nology. When a 30-year-old myope utilizes his or her best optical correction and has nighttime glare in combination with higher order aberrations, a wavefront-guided treat- ment (WFG) is a quality option. If a patient has had previous refractive surgery and had visually significant higher order aberrations induced, a WFG treatment can be very helpful. For all other situations, we offer the patient wavefront-guided or wavefront-op- timized (WFO) PRK, LASIK, or SMILE. In this article, William Trattler, MD, Michael Greenwood, MD, Michael Gordon, MD, and A. John Kanellopoulos, MD, discuss wavefront-guided and wavefront-optimized technology and how they use them to treat their patients. Both have a place, and in our center, we utilize both technologies. Thank you to our contributors for sharing their experience, knowledge, and opinions. Vance Thompson, MD, Refractive editor The wavefront measurement principle with a Tscherning device, in which wavefront deviation data are derived from projected patterns on the retina, imaged, and analyzed Source: A. John Kanellopoulos, MD Refractive editor's corner of the world It's an excellent treatment for patients who have a clear lens and pre-existing higher order aberra- tions, Dr. Greenwood said. "Howev- er, it might not be the best option for someone who is in his or her 50s and has some lens changes; the wavefront is picking up aberrations that are from the lens rather than from the cornea. You would be treat- ing the higher order aberrations in the lens," he said. According to Michael Gor- don, MD, San Diego, "The thought behind wavefront-guided treatments is that if we can measure wavefront aberrations with a reliable wavefront sensor and we have a scanning spot laser that has a tracker, we would be able to correct wavefront errors and make quality of vision better. That's where wavefront came about. How- ever, unless you get above 0.4 µm of RMS higher order aberrations, you don't see better results than with wavefront-optimized." The problem with wavefront- guided treatments is that they are dynamic. "In other words, they

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