Transepithelial accelerated versus conventional corneal collagen crosslinking in patients with keratoconus: a comparative study

Carolina Madeira,1 Ana Vasques,2 João Beato,1 Gonçalo Godinho,1 Luís Torrão,1 Manuel Falcão,1,3 Fernando Falcão-Reis,1,3 João Pinheiro-Costa1,4 1Department of Ophthalmology, Centro Hospitalar de São João, Porto, Portugal; 2Faculty of Medicine, University of Porto, Porto, Portugal; 3Department of Surgery and Physiology, Faculty of Medicine, University of Porto, Porto, Portugal; 4Department of Biomedicine, Faculty of Medicine, University of Porto, Porto, Portugal Purpose: To systematically compare the efficacy of transepithelial accelerated corneal collagen crosslinking (TE-ACXL) with conventional corneal collagen crosslinking (C-CXL) in patients with progressive keratoconus. Methods: Eyes of patients with progressive keratoconus who were treated with C-CXL (3 mW/cm2 for 30 minutes) were compared with those who underwent TE-ACXL (6 mW/cm2 for 15 minutes). Best-corrected visual acuity (BCVA), keratometry values, corneal thickness, and topometric indexes were compared before CXL, and at 2 months, 6 months, and 12 months postoperatively. Results: The study enrolled 26 eyes of which 16 had TE-ACXL and 10 had C-CXL. Both groups were comparable at baseline and 12 months in terms of BCVA (P=0.16 and P=0.57), Kmax (maximum keratometry) (P=0.31 and P=0.73), pachymetry (P=0.75 and P=0.37), index of surface variance (ISV) (P=0.45 and P=0.86), index of vertical asymmetry (IVA) (P=0.26 and P=0.61), and index of height decentration (IHD) (P=0.27 and P=0.86, respectively). We did not observe significant differences between preoperative and 12-month postoperative readings in within-group analysis: ΔKmax (TE-ACXL, -2.13±5.41, P=0.25 vs C-CXL, 0.78±1.65, P=0.17), Δpachymetry (TE-ACXL, 4.10±14.83, P=0.41 vs C-CXL, -8.90±22.09, P=0.24), ΔISV (TE-ACXL, -8.50±21.26, P=0.24 vs C-CXL, 3.80±12.43, P=0.36), ΔIVA (TE-ACXL, -0.12±0.31, P=0.26 vs C-CXL, 0.03±0.18, P=0.61), and ΔIHD (TE-ACXL, -0.03±0.07, P=0.18 vs C-CXL, -0.01±0.03, P=0.88). Conclusion: Both TE-ACXL and C-CXL were similarly effective. Further follow-up is required to determine whether these techniques are comparable in the long-term. Keywords: cornea, keratoconus, crosslinking, transepithelial, riboflavin, ultraviolet radiation, keratometr