Results obtained with wavefront-optimized LASIK are equivalent to those achieved with wavefront-customized LASIK, according to a retrospective study of 148 patients. The wavefront-optimized approach also presents an option for the approximately one-third of patients who cannot undergo customized treatment for one of several reasons, according to the ophthalmologist who conducted the research.
"I think most of the benefit of wavefront-customized ablation, indeed, is due to the optimization of the peripheral ablation profile, something that is fixed from the outset in [wavefront-optimized treatment], said Dr. Stulting, professor of ophthalmology, director of the cornea service, and director of refractive surgery at Emory University, Atlanta.
Dr. Stulting participated in the first physician-sponsored clinical investigation of LASIK before the FDA approved the first refractive laser for use in the United States and has performed LASIK procedures since 1994.
Using what he described as "a fairly unsophisticated wavefront analysis" 15 years ago, Dr. Stulting identified and tried to address what today are known as positive spherical aberrations.
"We did that by using the algorithms that were supplied with the laser but blocking some of the pulses that came out at the right time to place more energy in the periphery than we did in the center, because we weren't ablating enough tissue in the periphery relative to the center," he said. "We can do that much more efficiently today."
Wavefront-optimized ablations have changed the algorithm that Dr. Stulting used in the early days of LASIK, he said, and spherical aberrations no longer are induced. Despite these advancements, however, Dr. Stulting said many believe that custom treatment remains the standard of care.
"As time has gone by and I've had an opportunity to use [wavefront-optimized treatment], I've come to know that that's not the case," he said.
Many times, however, Dr. Stulting said, the correction peripheral ablation profiles of refractive lasers are not used in conventional treatments, and conventional treatments using one laser compared with a wavefront-optimized treatment performed with another laser are not the same thing. Results of customized treatments versus conventional treatments using the same laser look better because the conventional treatment induced spherical aberrations, he said.
"It's not possible to separate the effect of the peripheral algorithm adjustment from the effect of the custom treatment," Dr. Stulting added.
Accurate measurement and alignment of the delivery system are vital to minimize irregularities associated with the ablation process of custom treatments, he said.
"If you sit back and you think about it, you'd probably reach the conclusion that a custom treatment will work best for highly aberrated eyes because the 'noise level' is small compared with the gain that you get from treating the irregularities," he said. "The question is, how many eyes fall into this category, and what is the difference between custom and optimized treatment for the average patient?"