Laser in situ keratomileusis: ablation on the flap and stromal bed in a primary treatment

Abstract

This paper describes a retrospective study of 22 cases in which simultaneous ablation of the flap and stromal bed was performed during primary laser in situ keratomileusis (LASIK) in eyes with thin corneas or topographic abnormalities. Twenty cases had low pachymetry (512.2 ± 10.4 μm) and two had topographic asymmetry (inferior-superior difference more than 1.5 D). Preoperatively, the mean spherical equivalent (SE) was −5.61 ± 1.72 D, the cylinder was −1.78 ± 1.24 D, and the best spectacle-corrected visual acuity (BSCVA) was 0.77 ± 0.19. In every case, the spherical ablation was divided between the stromal bed and the back of the flap, with a maximum flap ablation of 3.0 D, according to a nomogram developed by the surgical team. The mean dioptric correction on the flap was −1.73 ± 1.08 D and on the stromal bed was −4.77 ± 1.89 D. All components of the toric ablation were performed on the stromal bed. Postoperatively, the mean SE was −0.21 ± 0.39, the reduction in cylinder was 1.69 ± 0.74D, and the BSCVA was 0.77 ± 0.20. No eyes had an increase in refractive astigmatism. Uncorrected visual acuity was 20/40 or better in all cases (100%) and 20/25 or better in 13 cases (59.1%). No eyes lost more than one line of best corrected visual acuity. The authors conclude that simultaneous ablation on the flap and stromal bed in cases of low pachymetry or topographic error was predictable and effective.—Michael D. Wagoner