JUN 14, 2019
This prospective study compared the outcomes of wavefront-optimized (WFO) ablation versus topography-guided ablation (TGA) in patients who had laser-assisted in situ keratomileusis (LASIK) for myopia or myopic astigmatism.
For each patient, 1 eye received WFO ablation while the other eye received TGA with the Contoura system (LYRA protocol), both using the WaveLight EX500 excimer laser and the WaveLight FS200 femtosecond laser. Participants were between 18 and 35 years old and had spherical myopia between 0.5 and 8.0 D, astigmatism between 0.0 and 3.0 D, and a maximum spherical equivalent of -8.0 D. Patients were excluded from the study if they had a history of corneal scarring, previous surgery, ectasia, dry eye, pachymetry less than 480 microns or any ocular pathology.
The study determined that the refractive outcomes of WFO and TGA LASIK were statistically similar, with a trend toward improved uncorrected distance visual acuity (UDVA) in the TGA LASIK group. Eyes that underwent TGA LASIK showed a significantly lower induction in vertical and horizontal coma and had a smaller amount of tissue ablation than eyes that received WFO LASIK. Both groups had a statistically similar percentage of eyes that achieved within 0.50 D of emmetropia.
The study was small and included data from only 64 eyes. The authors did not note whether a nomogram adjustment was used, which is important because the WaveLight is known to need an astigmatic and coupling adjustment to achieve optimal refractive results. Furthermore, it is difficult to compare the 2 eyes given that those who qualified for the LYRA protocol had anterior corneal astigmatism that was more consistent with refraction, while the WO treatments did not take this into account. Another limitation is that the aberration data were measured by the Pentacam and Contoura, and did not account for the entire optical system.
Consideration of postoperative HOAs is essential to providing patients with the best possible visual results. Long-term corneal stability is also important, so preservation of corneal tissue should be considered as well. Though this study showed improved UDVA and overall refractive outcomes, the study groups were not uniform. Demonstrating improved visual results with WFO or TGA in more uniform groups might help surgeons deliver the most optimal visual results.