Optimal Balance of Wavefront Aberrations in Photorefractive Keratectomy

Abstract

PURPOSE: To determine the ratio of defocus (Z4) to spherical aberration (Z12) in patients with optimal visual performance 10 years after multifocal aspheric photorefractive keratectomy (PRK). METHODS: The optimal ratio of defocus to spherical aberration was determined in 16 presbyopic patients (32 eyes) with 10-year follow-up after aspheric multifocal PRK with good to excellent visual acuity postoperatively and the absence of mesopic symptoms such as halos and glare. All patients were satisfied with their near and far vision. The NIDEK OPD-Scan was used to measure wavefront aberrations postoperatively for a 6-mm pupil diameter to the 6th Zernike order. Preoperative manifest refraction spherical equivalent (M RSE) was -7. 61 ±1.04 diopters (D) (range: -6.25 to -10.00 D). RESULTS: At 10 years postoperatively, mean spherical equivalent refraction was -0.49 ±0.96 D. All eyes were within 1.00 D of the intended refraction. The ratio of Z4/Z12 for patients with optimal outcomes was 3.07±1.36. CONCLUSIONS: The ratio of Z4/Z12 generated in this study determines the optimum balance of defocus to spherical aberration required for excellent outcomes in patients undergoing multifocal aspheric PRK. [J Refract Surg. 2007;23:S1037-S1040.]