Comparing Asphericity and High-order Aberration Changes, before and after Optimized PRK with Wavelight Allegretto EX500 and Technolas Teneo 317 Lasers in Myopic-astigmatic Patients

To compare maintaining corneal asphericity and high-order aberration changes in optimized PRK for myopic astigmatism patients, using Allegretto EX500 (WaveLight Allegretto Wave Eye-Q laser devices; Alcon Laboratories, Inc., Fort Worth, TX) and Technolas Teneo 317 (Bausch & Lomb, Rochester, NY). The patients with myopic astigmatism, whose range of myopic was between 1 and 8 diopters, and maximum astigmatism of 2.5 diopters, were selected based on inclusion and exclusion criteria and, then, randomly operated with one of the Allegretto EX500 and Technolas Teneo 317 devices. Before the operation, a complete visual examination (visual acuity, refraction, Slit lamp, and Fundoscopy) and imaging including orbscan, zywave, and topolyzer were performed. The examinations were repeated 6 months after surgery. The results were compared before surgery and between the two devices. This clinical trial study was performed on 97 eyes of 49 patients with mean age of 28±5 years. Six months after surgery, visual acuity with the best correction was similar between the two groups (P=0.152). The mean spherical equivalent before surgery was -3.43±1.29 and -2.91±1.29 (P=0.047) and 6 months after surgery, -0.14± 0.19 and -0.08±0.23 (P=0.173) in the Allegretto and Teneo groups, respectively. There was no significant difference between the two groups before and after the surgery (P>0.05) between the third and fourth order corneal aberrations. The ocular higher order aberration increased from 0.3±0.1 and 0.31±0.12 (P=0.639) to 0.43±0.2 and 0.180±.42, (P=0.828) in the Allegretto and Teneo, respectively. Corneal asphericity was at 30° before operation -0.3±0.12 and -0.38±0.51 (P=0.25) and after operation, 0.28±0.26 and 0.28±0.25 (P=0.858) in the Allegretto and Teneo groups. This increase was higher per a diopter of spherical equivalent in Teneo group (P= 0.628). The results of the treatment of the two Allegretto and Teneo devices were the same in correction of myopic astigmatism, although the Allegretto device induces less changes in asphericity, and the Teneo device induces less higher-order aberrations.