Eyeworld

EW FEATURE 82 Laser vision correction • February 2018 diopter of correction. If the patient is borderline in corneal thickness compared to the correction given, he will do the procedure traditional to spare some of the stroma. Dr. Durrie likes to analyze a Pentacam (Oculus, Wetzlar, Germa- ny) picture, and if he finds that the patient has asymmetric astigmatism, he will choose either wavefront- guided or topography-guided. Corneal wound healing Dr. Wilson said that patients who have abnormalities of wound healing are not good candidates for LASIK or PRK. If patients have ABMD, they are better treated by surface ablation because you allow the basement membrane to regen- erate, he said, adding that it could take a few years to reacquire the changes of the duplicated basement membrane. Otherwise, Dr. Wilson said that wound healing issues don't com- monly drive his choice between LASIK and PRK. This decision is based more on corneal topography, thickness, etc. "It's gotten fairly simple now because you have to maximize patients' tear film and meibomian glands beforehand," Dr. Durrie said. Postoperatively, his practice follows their own patients, so if there's something going on, it can be treat- ed immediately. "As far as medica- tions are concerned, we're using the same medications on all three," he said. This includes antibiotics for a week and steroids for a week, 4 times a day. This regimen is tapered down depending on any preopera- tive conditions. Dr. Doane thinks that it is im- portant to understand the massive improvement in outcomes with the advent of optimized treatment patterns that enlarged the short axis of astigmatic treatments, which diminished night symptoms and minimized regression of astigmatic correction. "It is also important to realize that a 6-mm ablation zone for excimer laser ablations, if well centered, is an optimal trade-off of preventing night symptoms and minimizing 'shrinkage' of the effective optical zone on topogra- phy, as was seen with early 4–5 mm ablation zones of the mid 1990s performed internationally," Dr. Doane said. Recent advancements Dr. Doane said that the one area that is seeing relatively quick ad- vancements is SMILE. "One of the early knocks on SMILE was slow vision recovery," he said. "This was the case with femtosecond lenticule extraction where a LASIK-like flap was created and the lenticule was pealed from the stromal bed," he said. Over the past 12–24 months it has become clear how important spot and track spacing and energy optimization are for quick recovery of vision essentially equal to LASIK postop day 1 outcomes, Dr. Doane said. "Since FDA approval, we have been lowering energy settings and cannot wait until we can increase our current spot and track spacing of 3.0 microns to upward of 4.5 microns," he said. "Not only will the dissection of the lenticule be improved, but excellent postop day 1 visual acuities will be expected and achieved." Dr. Durrie noted that there may be some new gels coming, which could aid in faster visual recovery for PRK patients. "PRK is a good procedure, it's just the slow visual recovery that throws it off," he said. As far as SMILE, Dr. Durrie said the most important thing is get- ting the technique down. He noted that internationally, some surgeons have been able to adjust some of the laser parameters and make the cuts smoother with less laser energy. "Being able to upgrade to this would be great," he said, adding that it would also be beneficial to even- tually be able to reach in and take the lenticule out without having to dissect at all. With LASIK, Dr. Wilson noted that the biggest change was the fem- tosecond laser for making flaps. He used the microkeratome for many years before, and he was always concerned about the potential for buttonholes and other complica- tions. "It doesn't even enter my mind anymore with the femtosec- ond laser," he said. Occasionally, he will have an issue with the laser, like in one quadrant where the side cut won't be complete. "But most of those, I can release with a lamellar dissecting blade and go ahead with the procedure," he said. As far as PRK, Dr. Wilson said the biggest advance has been the use of mitomycin-C to limit haze. The remaining frontier in PRK is the discomfort that patients experience for 2–3 days, he added. EW Editors' note: Dr. Durrie has financial interests with Alcon and Johnson & Johnson Vision. Dr. Doane has finan- cial interests with Carl Zeiss Meditec. Dr. Wilson has no financial interests related to his comments. Contact information Doane: jdoane@discovervision.com Durrie: ddurrie@durrievision.com Wilson: WILSONS4@ccf.org Choosing continued from page 80 Comparison of PRK, LASIK, and SMILE Pravin Vaddavalli, MD, compares various refractive procedures like PRK, LASIK, and SMILE. EWReplay.org

• Blank Page
• Blank Page (1)