Comparison of Zernike and Fourier Wavefront Reconstruction Algorithms for Myopic Wavefront-Guided LASIK

Abstract

Purpose:: A novel wavefront reconstruction algorithm utilizing Fourier analysis was developed for wavefront-guided LASIK treatment. The purpose of this study is to compare the clinical results of conventional Zernike algorithm and new Fourier algorithms in myopic patients undergoing wavefront-guided LASIK.

Methods:: Among 104 eye of 52 patients undergoing myopic wavefront-guided LASIK, 80 eyes were treated with Zernike algorithm (age: 30.3 + 8.3 years, manifest refractive spherical equivalent (MRSE): -4.6 + 1.8 D), and 24 eyes were treated with Fourier version (age: 30.4 + 9.9 years, MRSE: -5.0 + 1.9 D). Wavefront sensor WaveScan (VISX, USA) was used to acquire wavefront data and the data were analyzed with both algorithms. After 9-mm diameter and160-micro thick flap was created with a microkeratome (MK-2000, Nidek, Japan), laser ablation was performed with VISX Star S4 without activating iris registration option. At 1 week and 1, 3, 6 months postoperatively, uncorrected visual acuity (UCVA), best corrected visual acuity (BCVA), wavefront aberration, and contrast sensitivity were measured. We measured contrast sensitivity, low-contrast visual acuity, and letter contrast sensitivity. From the contrast sensitivity data, the area under the log contrast sensitivity function (AULCSF) was calculated. Postoperative wavefront aberration was measured with a Hartmann-Schack aberrometer (KR-9000 PW, Topcon, Japan).

Results:: Both algorithms significantly improved UCVA and BCVA postoperatively, but there was no significant difference between the two algorithms. In wavefront aberrations, no significant differences in 3^rd-oder, 4^th-order and high-order aberrations were observed between the two algorithms. AULCSF at 3 month post-operation was significantly larger in Fourier group than in Zernike group. Letter contrast sensitivity was significantly better in Fourier group than in Zernike group at all post-operative points.

Conclusions:: Use of Fourier analysis algorithm for wavefront-guided LASIK can provide superior visual outcome to conventional Zernike algorithm.

Keywords: refractive surgery: LASIK • contrast sensitivity • visual acuity