Safety and Efficacy of Myopic LASIK performed on Thin Corneas

Abstract

Purpose: The aim was to report on the visual outcomes and safety of myopic LASIK performed in patients with corneas of central thickness below average(<540μm) and normal topography. Methods: This is a retrospective cohort study conducted at a private practice setting on Mexican Hispanic patients who underwent myopic LASIK between January 2014 and January 2015. An analysis of records of patients >18 years-old with previous normal topography, stable refraction, corrected visual acuity ≥ 20/20 (Snellen), Central Corneal Thickness (CCT) < 540μm and at least 12 months follow up after surgery was conducted. The main outcome measures were standard visual outcomes (efficacy, safety, refractive stability) and Percent Tissue Altered (PTA) analysis was conducted. Results: A total of 51 patients (102 eyes) were included; 56% (n=57) were female. The mean age was 26.52 ± 8.06 (range 18-55 years) with a mean follow up of 13.9 ± 1.2 months. Preoperative CCT was 515.44 ± 17.87μm (range 452- 540μm), with a mean refractive spherical equivalent (SEQ): -4.08 ± 2.17 D (range -0.75 to -9.75 D), and mean refractive cylinder: -1.44 ± 1.29 D (range 0.00 to -6.00 D). Mean predictability of postoperative SEQ was -0.20 ± 0.40 D (range -1.25 to +1.25). Postoperative SEQ was ±0.50 D in 71%, ±1.00 D in 93% of the eyes. Postoperative uncorrected distance visual acuity was ≥20/20 in 78% and ≥20/25 in 95%. One line of CDVA was lost in 3% of the eyes, no eyes lost ≥2 lines. No ectasia cases were observed during follow-up. Conclusion: LASIK surgery in Mexican Hispanic patients with thinner than “normal” corneas (<540 μm) is safe, efficient and predictable at 1 year follow up for myopic refractive corrections with no evidence of postoperative keratectasia.