LASIK or femto-LASIK but do have some optical side effects and are not reversible. “Corneal laser vision corrections should be limited to moderate myopia because of the loss in quality of vision,” he said, noting the higher the refractive error, the greater the aberrations. Phakic IOLs offer a good safety profile, faster visual recovery, do not create dry eye, boast fewer optical aberrations and are fully reversible, Dr. Knorz said. Further, in his experience with the Visian ICL (Starr Surgical), “I’ve never seen corneal decompensation,” contrary to earlier reports when the technology was first introduced.“Phakic IOLs give patients significantly better night vision than corneal laser surgery and does not interfere with future procedures,” he said, so when the patient needs cataract surgery down the road, “just remove the ICL.” When a –5 D myope wants laser vision correction, Dr. Knorz said the order of surgery he would recommend is phakic IOL (because of the quality of vision and reversibility), followed by laser lenticule extraction (less dry eye than LASIK), then femto-LASIK (higher patient comfort compared to surface ablation), and finally, surface ablation. But only for younger patients. “If that same patient is over 50 years old, I’d recommend refractive lens exchange,” he said. Is Ray-Tracing LASIK More Than a Fad? During the Faster Than the Speed of Light symposium here at the 35th APACRS Singapore conference, Chandra Bala, MD, said the evolution of refractive surgery has moved from PRK to wavefront optimized, to wavefront guided, to topography-guided, and now to ray-tracing LASIK. “I would argue that the purpose of refractive surgery is not to remove a thin lens from the cornea, but to change the angle of incidence of the ray as it strikes the cornea so that the eye may do the rest of the focusing,” he said, “But in order to do that, the ray should strike such that you can predict where it will strike the lens.” Innoveyes’ ray tracing algorithm uses multiple measure surfaces and unmeasurable assumed elements to create a baseline individualized eye model, he said. The all-in-one device does all the steps in one sitting, including refraction, whole eye aberrometry, topography, central corneal thickness, anterior chamber depth, and axial length, among others. In his hands, 8% of eyes achieved 20/10, 50.5% achieved 20/12.5, and 89.3% achieved 20/16; 96% of eyes were within 0.5 D, and 98% had < 15° angle of error. “Ray tracing is a new era in our thinking and ability to correct refractive error,” he said. “We now recognize the need for an individual eye model — an ‘eyevatar’ — for creating a personalized treatment plan.” 10 Years of SMILE With more than a decade of commercialization, “why hasn’t small incision lenticule extraction (SMILE, Zeiss) replaced LASIK?” asked Patrick Versace, MD, during the symposium Faster Than the Speed of Light. Studies show there are no differences between SMILE and femto-LASIK in uncorrected visual acuity or refractive outcomes, but SMILE is significantly better in reducing higher order aberrations and spherical aberrations. While the two techniques produce similar tear film osmolarity and Schirmers’ test results, tear break-up time and Ocular Surface Disease Index outcomes favor SMILE, he said. “Patient acceptance is higher, as there’s no flap, no down time, a rapid return to sports, and less dry eye,” he said. Conversely, LASIK has a much quicker visual recovery. There are five lenticule extraction devices on the market, each of which uses a different amount of energy per pulse. “But what we don’t know is what part of the energy matters (total energy, or energy per pulse, or energy focus, or ease of dissection),” he said. “We only know using less energy is better.” Other upsides are that SMILE can correct myopia up to –10 D, but vertical coma is increased after SMILE, and to date there is no method to digitally register the lenticule cut location, meaning a second lenticule cut would be optimal, but surgically complex to place identical to the first incision. Digital marking is only available on the Zeimer Z8 device, although it may be planned on Johnson & Johson’s Elita. “We can make lenticular surgery greater by introducing auto centration and toric alignment, having easy lenticule removal, improving the precision of the energy delivery, and allowing enhancements with secondary lenticule removal,” he said. EWAP NEXUS CoNNECtiNg EvEryoNE & EvErythiNg
RkJQdWJsaXNoZXIy Njk2NTg0