38 EyeWorld Asia-Pacific | December 2024 LEARNING FROM THE MASTERS IMPORTANT DATES 21 SEPTEMBER 2024 Abstract Submission Open • 21 NOVEMBER 2024 Registration Open • 21 FEBRUARY 2025 Deadline for Abstract Submission • 21 MAY 2025 Deadline for 1st Tier Early Bird Registration Rates Deadline for Submission of ePosters & Videos for Film Festival apacrs2025.org Dada Harir Stepwell in Ahmedabad, India REFRACTIVE SURGERY A word about Zernike Dr. Gatinel spoke at length about Zernike polynomials and how they may not always accurately represent the visual quality because they sometimes misrepresent defocus and other aberrations. Dr. Gatinel published an “alternative wavefront reconstruction method” in 2020, proposing that “some of the inherent limitations of Zernike polynomials in clinical ophthalmic application can be solved by a novel set of polynomials forming an alternative higher order basis. The new basis provides a clear separation between modes containing lower order terms versus higher order terms and offers clinicians a more clinically realistic wavefront analysis.”1 In his interview with EyeWorld, Dr. Gatinel said that the real defocus people select to correct with spectacles is not the Zernike defocus. “Zernike defocus is in displays where you would say that’s the defocus, but this is particular in eyes with a lot of spherical aberrations, which are eyes with a lot of problems. This Zernike defocus is not the refractive defocus,” he said. In addition, the retinal image simulations and related metrics for HOAs using Zernike decomposition are not always clinically relevant as some low order aberrations such as defocus or astigmatism are embedded in the expression of some higher order Zernike modes. Reference 1. Gatinel D, et al. An alternative wavefront reconstruction method for human eyes. J Refract Surg. 2020;36:74–81. 3. For enhancements, use SD-OCT to determine whether LASIK or PRK is better (PRK with mitomycin-C for cases with thin pachymetry and thick flaps; don’t relift flaps if you can’t identify the thickness profile). 4. Recognize that the ablation depth for a specific refraction increases with the magnitude of aberrations, leading to overcorrection. 5. Discuss with the patient that this might be a two-step treatment due to the potential shift in lower order aberrations when correcting HOAs. Dr. Rocha’s presentation also emphasized that management of HOAs is technology dependent. Not all platforms perform the same, and HOA treatment is subject to technology limitations.
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