Long-term safety and efficacy follow-up of prophylactic higher fluence collagen cross-linking in high myopic laser-assisted in situ keratomileusis

Abstract

Background: The purpose of this study was to evaluate the safety and efficacy of ultraviolet A irradiation cross-linking on completion for cases of high myopic laser-assisted in situ keratomileusis (LASIK).

Methods: Forty-three consecutive LASIK cases treated with femtosecond laser flap and the WaveLight excimer platform were evaluated perioperatively for uncorrected visual acuity, best corrected spectacle visual acuity, refraction, keratometry, topography, total and flap pachymetry, corneal optical coherence tomography, and endothelial cell count. All eyes at the completion of LASIK had cross-linking through the repositioned flap, with higher fluence (10 mW/cm(2)) ultraviolet light of an average 370 μm wavelength and 10 mW/cm(2) fluence applied for 3 minutes following an earlier single instillation of 0.1% riboflavin within the flap interface. Mean follow-up duration was 3.5 (range 1.0-4.5) years.

Results: Mean uncorrected visual acuity changed from 0.2 to 1.2, best corrected spectacle visual acuity from 1.1 to 1.2, spherical equivalent from -7.5 diopters (D) to -0.2 D, keratometry from 44.5 D to 38 D, flap pachymetry from 105 μm to, total pachymetry from 525 to 405, and endothelial cell count from 2750 to 2800. None of the cases developed signs of ectasia or significant regression during follow-up.

Conclusion: Prophylactic collagen cross-linking for high-risk LASIK cases appears to be a safe and effective adjunctive treatment for refractive regression and potential ectasia. This application may be viewed as prophylactic customization of the biomechanical behavior of corneal collagen.

Keywords: high-risk; laser-assisted in situ keratomileusis; post-LASIK ectasia; prophylactic collagen cross-linking.

Figure 1

Riboflavin solution applied over the bare stroma without contact with the LASIK flap for 60 seconds. Abbreviation: LASIK, laser-assisted in situ keratomileusis.

Figure 2

Flap is repositioned, and the riboflavin-yellow tinge is visualized in the corneal stroma prior to application of higher fluence ultraviolet light.

Figure 3

Postoperative uncorrected and corrected distance visual acuity at 12 months.

Figure 4

Image showing keratometric stability over the first 24 months for the group measured by Scheimpflug-based tomography.

Figure 5

Safety data for the group at 12 months.

Figure 6

Spherical equivalent correction predictability for the group at 12 months.

Figure 7

Anterior segment OCT image of a treated cornea. Note: There is hyper-reflectivity evident over and under the LASIK flap (red arrows). Abbreviations: OCT, optical coherence tomography; LASIK, laser-assisted in situ keratomileusis.