Evaluation of Corneal Biomechanics After Excimer Laser Corneal Refractive Surgery in High Myopic Patients Using Dynamic Scheimpflug Technology

Eye Contact Lens. 2017 Nov;43(6):371-377. doi: 10.1097/ICL.0000000000000280.


Objective: To compare the effect of femtosecond-assisted thin flap laser-assisted in situ keratomileusis (FS-LASIK) and photorefractive keratectomy with mitomycin-C (PRK-MMC) in highly myopic patients (>7.0 D [D]) on corneal biomechanical parameters.

Methods: In this prospective comparative interventional case series, 60 patients (30 patients in each group) with a manifest refractive spherical equivalent (MRSE) greater than 7.0 D were enrolled. Corvis ST parameters were measured before and at 3 and 6 months postoperatively.

Results: Preoperatively, mean MRSE was -8.65±1.51 D in FS-LASIK and -8.04±1.70 D in PRK-MMC groups (P=0.149), and corneal thickness was 570.67±36.79 μm and 507.12±32.55 μm, respectively (P<0.001). At 6 months, both groups showed significantly higher applanation (A) 2 time and A2-velocity (P<0.05 in both), whereas intraocular pressure (IOP), corrected IOP, A1 time, A1-velocity, and radius at highest concavity were significantly reduced (P<0.05 in all). In the FS-LASIK group, there was a significant increase in deformation amplitude (DA) (P=0.001), and significant decreases in A2-length (P=0.004). Peak distance increased in the PRK-MMC group (P=0.029). At 6 months, after controlling for fellow eye correlations and preoperative corneal thickness between the two groups, decreases in IOP, A1-time, A2-length and radius, and the increase in DA was greater in FS-LASIK.

Conclusion: This study demonstrated significant changes in Corvis ST ocular biomechanical metrics after both PRK-MMC and FS-LASIK in high myopic patients, indicating the significant effect of excimer laser refractive surgery on corneal biomechanical properties. However, changes that occur with FS-LASIK are more significant than with PRK-MMC. Further randomized studies are needed to better characterize the pattern of biomechanical changes associated with each type of surgery.

Publication types

  • Comparative Study

MeSH terms

  • Adult
  • Biomechanical Phenomena
  • Cornea / physiopathology*
  • Cornea / surgery
  • Female
  • Humans
  • Intraocular Pressure / physiology
  • Keratomileusis, Laser In Situ*
  • Male
  • Middle Aged
  • Mitomycin / administration & dosage
  • Myopia, Degenerative* / physiopathology
  • Myopia, Degenerative* / surgery
  • Photorefractive Keratectomy*
  • Prospective Studies
  • Visual Acuity / physiology
  • Young Adult


  • Mitomycin