Post-FDA Approval Results of Epithelium-Off, Full-Fluence, Dresden Protocol Corneal Collagen Crosslinking in the USA

INTRODUCTION: The purpose of this non-comparative, prospective, observational study was to evaluate the post-US Food and Drug Administration approval outcomes of epithelium-off, full-fluence, Dresden protocol corneal collagen crosslinking (CXL) for the treatment of progressive keratoconus (KCN) and post-refractive corneal ectasia at a US academic tertiary medical center. METHODS: This study involved 125 eyes of 97 patients with KCN and 13 eyes of 12 patients with post-refractive ectasia which underwent CXL between November 2016 and September 2019. Best spectacle-corrected visual acuity (BSCVA) and corneal topographic parameters were measured preoperatively, at postoperative month 1 (POM-1), and between postoperative months 3 and 24 (POM 3-24). RESULTS: Best spectacle-corrected visual acuity, flat keratometry, steep keratometry, and mean corneal power worsened at POM-1 (p < 0.01) with a return to preoperative values at POM 3-24. Maximum keratometry (Kmax) steepened at POM-1 and then improved beyond preoperative levels at POM 3-24 (p < 0.01 and p = 0.03, respectively). Pachymetry at the apex and pupil decreased at POM-1 and POM 3-24 (p = 0.03). Pachymetry at the thinnest point decreased at POM-1 and trended toward reduction at POM 3-24 (p < 0.001 and p = 0.06, respectively). Visual and tomographic outcomes were similar between pediatric and adult populations, and between KCN and post-refractive ectasia patients. CONCLUSIONS: Real-world results of CXL in the USA are similar to those reported in prior studies, demonstrating an initial worsening of BSCVA, pachymetry, and keratometry followed by corneal flattening and preservation of visual acuity. Improvements in Kmax and stability in visual acuity were observed over 24 months in children and adults with progressive KCN or post-refractive ectasia.