Correlation and regression analysis between residual gradation and uncorrected visual acuity one year after refractive surgery with LASIK, FS-LASIK, PRK, PRK Xtra techniques and the implantation of ICL® posterior chamber phakic lens in myopic correction

PLoS One. 2020 Sep 11;15(9):e0238399. doi: 10.1371/journal.pone.0238399. eCollection 2020.


Purpose: To analyze the influence of the final spherical equivalent (SE) in LogMAR uncorrected distance visual acuity (UDVA) one year after refractive surgery. We analysed refractive results, their predictability and efficacy, and the safety results of the different methods as secondary outcomes.

Setting: Refractive Surgery Unit of the Institut Català de Retina (ICR) in Barcelona, Spain.

Design: Retrospective, analytical observational study.

Methods: Retrospective and observational study of 654 eyes of 327 patients who underwent refractive surgery to treat their myopia or myopic astigmatism using LASIK, FS-LASIK, PRK, PRK Xtra or ICL-type lens implantation surgery were included.

Results: The correlation between the SE in absolute value was statistically significant in all techniques utilized, reaching higher values in the FS-LASIK and LASIK techniques, 0.774 and 0.706 respectively, and lesser values in PRK (0.480) and PRK Xtra (0.482). A significant adjustment via a univariate linear regression model could be implemented in all techniques, albeit the R2 coefficient of determination values were higher than those for the FS-LASIK (0.599) and LASIK (0.494) techniques.

Conclusions: There is a positive correlation between post-surgical SE value and post-operative LogMAR UDVA. These regression models can be adjusted to predict the final UDVA according to the final SE. The techniques that are most influenced by the final SE in terms of their visual results are FS-LASIK and LASIK.

Publication types

  • Observational Study

MeSH terms

  • Adult
  • Astigmatism / physiopathology
  • Astigmatism / surgery*
  • Female
  • Humans
  • Keratomileusis, Laser In Situ / adverse effects
  • Keratomileusis, Laser In Situ / methods*
  • Lens Implantation, Intraocular* / adverse effects
  • Lenses, Intraocular / adverse effects
  • Linear Models
  • Male
  • Myopia / physiopathology
  • Myopia / surgery*
  • Photorefractive Keratectomy / adverse effects
  • Photorefractive Keratectomy / methods*
  • Retrospective Studies
  • Spain
  • Treatment Outcome
  • Visual Acuity
  • Young Adult

Grant support

The authors received no specific funding for this work.