Leading refractive surgeons agree wavefront-guided (WFG) ablation is a significant advance in laser vision correction, but have different opinions about its role in treating myopic eyes with low higher-order aberrations (HOAs).
Ronald R. Krueger, MD, explained why he believes WFG ablation has no measurable advantage in these cases, defined as having total HOA root-mean-square (RMS) <0.3 µm. Steven C. Schallhorn, MD, presented evidence supporting its use.
Dr. Krueger noted that there are certain prerequisites for achieving reliable outcomes with a WFG treatment, including perfect centration and perfect eyetracker performance. However, these criteria are often not met in routine practice as suggested by study data on the occurrence of cyclorotation and iris recognition and tracking failure, said Dr. Krueger, medical director, refractive surgery, at the Cole Eye Institute, Cleveland Clinic.
"Cyclorotation of more than 2° has been reported as occurring in about two-thirds of eyes and associated with induction of HOAs, and there is also evidence that lateral decentration >0.08 mm during WFG ablation can degrade retinal image quality. In another paper, iris recognition failed in up to 10% of patients after multiple attempts and iris tracking failure occurred at a rate of 31%," he reported.
Addressing the concept that a WFG treatment has benefit for optimizing contrast and quality of vision through its ability to correct HOAs, Dr. Krueger presented data from a study he performed using adaptive optics showing that HOA <0.3 µm are not visually significant. He also cited a published paper showing that for ideal visual performance, HOAs should be optimized to maintain a prolate cornea, rather than minimized.
"This research indicated there is a certain dependence on preexisting aberrations, especially in eyes with low values," Dr. Krueger said.