Changes in corneal symmetry and tear film stability after laser asymmetric keratectomy in patients with keratoconus suspect: A retrospective study

Abstract

Keratoconus suspect (KCS) has been a contraindication of laser refractive surgery (LRS) due to postoperative corneal ectasia, but is well indicated with LRS combined with corneal remodeling using laser asymmetric keratectomy (LAK). This study compared the 2-year changes in corneal symmetry and tear film stability after laser epithelial keratomileusis-LAK (L-LAK) for new corneal remodeling in myopic patients with KCS. This retrospective case-control study included 31 eyes of 21 patients with KCS who had undergone L-LAK for corneal remodeling. L-LAK procedures included correction of original refractive errors (original ablation), ablation of the thick peripheral cornea to improve the corneal shape, and simultaneous central ablation to correct myopic shift (crescentic customized ablation). Preoperative and 2-year postoperative corneal symmetry were both evaluated using the total corneal central-thickness deviations in 4 directions on an Orbscan map (SUM) (in mu m). Two years postoperatively, the average spherical equivalent was decreased from -2.60 +/- 1.02 preoperatively to -0.41 +/- 0.33 D postoperatively (P = .001). The uncorrected distance visual acuity (UDVA) (LogMAR) was increased from 0.82 +/- 0.30 to 0.04 +/- 0.18 (P = .001), and 95% of the participants experienced an UDVA of 20/20 or better. The SUM (mu m) decreased from 140.86 +/- 48.20 preoperatively to 64.20 +/- 15.20 postoperatively (P = .001). The Kmean, Kmax, and central pachymetry also decreased (P = .001). The tear breakup time (TBUT) (seconds) increased markedly from 7.51 +/- 2.96 preoperatively to 19.40 +/- 3.65 at 2-year postoperatively (P = .001). There were no postoperative adverse events. Corneal remodeling using L-LAK is a safe technique that facilitates corneal symmetry, increases TBUT, and yields good postoperative visual outcomes without postoperative corneal ectasia.