Three different aspheric treatment algorithms of laser-assisted sub-epithelial keratectomy in patients with high myopia

Purpose: To compare visual outcomes and quality in high myopia patients treated using one of three aspheric treatment algorithms based on the NIDEK Advanced Vision Excimer Laser System. Methods: Sixty eyes of 60 high myopia patients (>-6 diopter) underwent topography-guided (CATz) (20 eyes), wavefront-guided (OPDCAT) (20 eyes), or topography and wavefront-guided (OPA) (20 eyes) laser-assisted sub-epithelial keratectomy. Visual acuity, manifest refraction spherical equivalent (MRSE), ocular and corneal higher order aberrations, corneal asphericity, point spread function (Strehl ratio) and modulation transfer function (MTF) were compared preoperatively and 1, 3 and 6 months postoperatively. Results: Six months after surgery, logMAR uncorrected visual acuity was 0.02 ± 0.09 in the CATz group, 0.02 ± 0.07 in the OPDCAT group and 0.02 ± 0.08 in the OPA group, and there were no statistically significant differences (P = 0.5355). No statistical differences were found among the three groups in MRSE (P = 0.3541). Induced spherical aberrations and the change of corneal asphericity were less in the OPA group than in the others (P < 0.0001). The MTF was slightly better in the OPA group than in the others. The Strehl ratio showed no statistically significant differences among the three groups. Conclusions: All three aspheric treatment algorithms were safe and effective in correcting high myopia. Among them, the OPA algorithm maintained optical quality and physiologic cornea longer than the others.