Aberration-neutral Ablation Pattern in Hyperopic LASIK With the ESIRIS Laser Platform

Abstract

To analyze refractive power changes, topographical changes, and aberrations induction after aberration-neutral (Aberration-Free") hyperopic LASIK using the SCHWIND ESIRIS laser platform. Thirty-three consecutive eyes of 19 patients were evaluated retrospectively. The outcomes were analyzed at 3 months. In all cases, standard examinations and pre- and postoperative topographical and corneal wavefront analysis with a Keratron topographer (OPTIKON 2000 SpA) were performed. The preoperative mean spherical equivalent refraction was +2.61 +/- 1.39 diopters (D) (range: +0.75 to +6.00 D) with a mean cylinder of 0.67 +/- 0.74 D (range: 0.00 to 4.00 D). Ablations were performed with the SCHWIND ESIRIS excimer laser system. Topographical changes of Maloney index, simulated keratometry (Sim-K), and K-readings at 5 and 7 mm were evaluated. Corneal aberrations up to the seventh order (36 Zernike terms) were measured. Corneal spherical aberration was +0.197 +/- 0.144 microm preoperatively and -0.040 +/- 0.206 microm postoperatively at the 6-mm analysis diameter. At 3 months postoperatively, 88% of eyes were within +/-0.50 D manifest refraction. Changes in refraction, Maloney indices, and Sim-K indices postoperatively were correlated with the intended correction. Induction of negative corneal spherical aberrations and increased prolate asphericity were correlated with the achieved defocus correction. No other Zernike mode was significantly correlated. Topographically, a corneal multifocality of <0.25 D was also observed. Analyzing the topographical maps, the corneal power change of the Maloney indices correlated with the intended correction. With the aberration-neutral (SCHWIND Aberration-Free) pattern, patients with hyperopia up to +5.00 D were treated safely and with good predictability. The induced corneal aberrations were less than those calculated with the classical profile and compared to the literature.