• Cornea/External Disease, Pediatric Ophth/Strabismus, Refractive Mgmt/Intervention

    Researchers compared the 5-year efficacy and safety of accelerated transepithelial (epi-on) and standard (epi-off) corneal collagen crosslinking (CXL) in children with progressive keratoconus.

    Study design

    This single-center, prospective, cohort study included 78 eyes of pediatric patients who underwent epi-on CXL or epi-off CXL for progressive keratoconus. Thirty-two eyes underwent epi-on CXL (30 minutes of impregnation followed by 5 minutes of irradiation at 18 mW/cm2) and 46 underwent epi-off CXL (30 minutes of impregnation followed by 30 minutes of irradiation at 3 mW/cm2). Visual acuity, refraction, keratometry and pachymetry were evaluated pre- and postoperatively at 1 and 5 years.


    Both groups experienced mean improvement in BCVA at 5 years, but 3 eyes that progressed in the epi-on CXL group lost lines of BCVA compared with no loss of BCVA in the standard epi-off CXL group. Cylinder in the epi-off CXL group significantly decreased by 0.66 D and 0.89 D at 1 and 5 years, respectively, while there was no change in cylinder in the epi-on CXL group. By 5 years, there was significantly more flattening in mean keratometry in the epi-off group than in the epi-on group (3.18 D vs. 0.09 D). Three of the 32 eyes (9.37%) in the epi-on group experienced Kmax progression greater than 1 D—all of which were noted by 1 year—whereas none of the eyes in the epi-off group experienced Kmax progression greater than 1 D at 5 years.


    One of the limitations of this study is the lack of randomization. In addition, the authors do not explain how they decided which patients would receive which treatment. However, at least there were no statistically significant differences in UCVA, BCVA, sphere, cylinder, keratometry or pachymetry between the 2 groups at baseline. Lastly, although the sample size is quite good for a single-institution study, a larger number of participants would be ideal.

    Clinical significance

    Standard epithelial-off CXL appears to be safer and more effective in flattening keratometry and halting progression compared with accelerated transepithelial CXL in the pediatric population.