A novel LASIK excimer laser customization approach that uses total eye aberration data and ray tracing to treat myopia and myopic astigmatism appears safe and effective and offers improved and more predictable outcomes, according to preliminary results published in Clinical Ophthalmology.
The consecutive case series evaluated 50 eyes of 25 patients who underwent femto-LASIK for myopia. An artificial intelligence platform initially calculated the ablation profile based on a case-by-case model eye using interferometry axial length data. Additionally, low- and high-order aberration calculations were performed through ray tracing based on wavefront and Scheimpflug tomography measurements. Over six months, the study evaluated VA, refractive error, keratometry, topography, high-order aberrations and contrast sensitivity.
The uniqueness of the ray tracing platform is centered on its customization of each refractive treatment based on actual individual eye measurements provided by the Sitemap diagnostic device. It essentially creates an “avatar” eye instead of the standard Gullstrand eye model, explains researcher A. John Kanellopoulos, MD. This data is then combined with an eye tracing of 2,000 rays using the tomography data from Scheimpflug imaging and retrograde information from the back of the retina to the anterior lens surface.
Higher aberrations have been entertained by wavefront treatments since the beginning of the 2000’s, and over the past eight years, topography-guided treatments came into play as a fix for irregular eyes with higher aberrations, Dr. Kanellopoulos says. “Now, ray tracing offers the ability to combine these two technologies into a theoretical model that also takes into account the way the laser works and the way tissue interacts with each given amount of laser vision correction.”
This is not a new entity, but it’s much faster, Dr. Kanellopoulos suggests. Previous technology took copious manual calculations, he explains. This is the first time all data can be calculated within seconds by a single device that is able to perform all imaging captures on any given human eye, all while producing lower and higher aberrations that can be transferred into an excimer laser and used on a myopic or myopic astigmatic eye with outstanding results, Dr. Kanellopoulus says.
At the six-month follow up, refractive error had improved from -5.06±2.54D to -0.11±0.09D, refractive astigmatism from -1.07±0.91D to -0.15±0.04D and topographic astigmatism from -1.65±0.85D to -0.26±0.11D.
About 65% of eyes gained one line of vision and 38% experienced an increase of two lines. Considering high-order aberration averages, the root mean square changed from 0.25μm to 0.35μm, and contrast sensitivity also improved postoperatively.
“I think we are looking at a new page in laser vision correction that goes beyond making patients independent of their spectacles. We are looking into an era where laser vision correction can act as a preemptive advantage to not only make patients independent of spectacles and contact lenses, but also improve the visual optics,” Dr. Kanellopoulos concludes. This will heighten the possibility of individuals seeing even better than they did with their glasses or contact lenses, since the procedure improves axial biologic optics, he notes.
Kanellopoulos AJ. Initial outcomes with customized myopic LASIK, guided by automated ray tracing optimization: a novel technique. Clin Ophthalmol. 2020;14:3955-63.