Optical Performance of the Cornea One Year Following Keratoconus Treatment with Corneal Collagen Cross-Linking

Curr Eye Res. 2018 Dec;43(12):1415-1421. doi: 10.1080/02713683.2018.1501802. Epub 2018 Jul 30.

Abstract

Purpose: The purpose of the study is to assess changes in optical performance of the cornea in patients with keratoconus following treatment with corneal collagen crosslinking (CXL).

Materials and methods: One hundred and eleven eyes of 111 consecutive keratoconus patients with 12-month follow-up after CXL were included. The changes in the visual acuity, manifest refractive errors, and corneal topographic parameters were evaluated. Sirius dual-scanning corneal tomography was used to determine the effectiveness of CXL on each patient's total corneal optical quality; preoperative and 12-month postoperative measurements were analyzed over a 4-mm stimulated pupil and were compared with regards to higher order corneal aberrations (total amount of higher order aberrations [HOAs], vertical coma, horizontal coma, vertical trefoil, oblique trefoil, and spherical aberration), vertical and horizontal modulation transfer function (MTF), and Strehl ratio of point spread function (PSF).

Results: At 12 months, there was a significant improvement in mean uncorrected visual acuity (UCVA) (P < 0.001), best corrected visual acuity (BCVA) (P < 0.001), spherical equivalent refraction (P = 0.007), and manifest astigmatic refraction (P < 0.001). The corneal topographic measurements revealed a significant decrease in the mean simulated keratometry-1, simulated keratometry -2, and maximum keratometry compared with the baseline measurements (P < 0.001, for all). In addition, there were significant improvements in mean root mean square error values for corneal total HOA (P < 0.001), vertical coma (P < 0.001), and vertical trefoil (P = 0.008) following CXL. Mean MTF and Strehl ratio did not change after CXL (P > 0.05). The improvement in UCVA significantly correlated with the changes in vertical trefoil (r = -0.191, P = 0.044), and the improvement in BCVA and the changes in manifest astigmatic correction were also significantly correlated (r = -0.247, P = 0.009) 12 months after CXL.

Conclusions: CXL treatment for keratoconus led to an improvement in visual, refractive, topographic, and most corneal HOAs outcomes at the 12-month follow-up. However, these improvements were not enough to increase corneal MTF and the Strehl ratio of PSF.

Keywords: Corneal collagen crosslinking; higher order aberrations; keratoconus; modulation transfer function; point spread function.

MeSH terms

  • Adolescent
  • Adult
  • Child
  • Collagen / therapeutic use*
  • Cornea / pathology
  • Corneal Topography
  • Cross-Linking Reagents / therapeutic use*
  • Female
  • Follow-Up Studies
  • Humans
  • Keratoconus / diagnosis
  • Keratoconus / drug therapy*
  • Male
  • Photochemotherapy / methods*
  • Photosensitizing Agents / therapeutic use
  • Refraction, Ocular / physiology*
  • Retrospective Studies
  • Riboflavin / therapeutic use*
  • Time Factors
  • Visual Acuity
  • Young Adult

Substances

  • Cross-Linking Reagents
  • Photosensitizing Agents
  • Collagen
  • Riboflavin