Accelerated CXL in Progressive Keratoconus: Comparison of Continuous Light Epi-Off, Pulsed Light Epi-Off, Continuous Light-Epi-On, and Pulsed Light Epi-On
Purpose
To compare the clinical results of four types of accelerated crosslinking (A-CXL) procedures in patients with progressive keratoconus.
Methods
115 eyes of 80 patients were enrolled in this comparative, interventional case series. 34 eyes had epi-off continuous light (30 mW/cm2, 4 min), 29 eyes had epi-off pulsed light (30 mW/cm2, 8 min; 1 sec on/1 sec off), 42 eyes had epi-on continuous light (45 mW/cm2, 2 min 40 sec) and 10 eyes had epi-on pulsed light (45 mW/cm2, 5 min. 20 sec;1 sec on/1 sec off) A-CXL with a total energy dose of 7.2 J /cm2. Uncorrected visual acuity (UCVA) and best spectacle-corrected visual acuity (BSCVA), sphere and cylinder, spherical equivalent (SE), corneal topography, pachymetry and aberrometry were evaluated at baseline and 3,6 and 12 months.
Results
Except in the epi-off pulsed light A-CXL group, Kmax values increased in the other 3 groups, but did not reach statistical significance. The meanK value increased in the continuous light A-CXL groups (p=0.005, p=0.007) whereas it was stable in the pulsed light A-CXL groups.The postoperative change in mean K in the epi-off pulsed light A-CXL group was found to be significantly different from the other 3 groups. There were no statistically significant differences in postoperative changes in UCVA, BSCVA and refraction values between the 4 groups. In the epi-off groups, stromal demarcation line was found to be deeper than the epi-on groups (171μ vs. 121 μ, p<0.001). No postoperative complications were observed except the occurrence of peripheral sterile infiltate in one eye in the epi-off continuous light A-CXL group.
Conclusion
A-CXL seems to be less effective in stabilizing or inducing regression in topographic parameters and improving the visual outcome in progressive keratoconus. Pulsed light treatment and epithelial debridment may slightly improve the efficacy of A-CXL.