Epi-off CXL Safer, More Effective Than A-Epi-on for Pediatric Keratoconus

Researchers found a significant decrease in anterior elevation in pediatric patients who underwent epi-off crosslinking, but no significant changes in anterior elevation values in those who underwent A-epi-on crosslinking.

Standard corneal crosslinking (epi-off CXL) was safer and more effective than accelerated transepithelial (A-epi-on) CXL in halting the progression of pediatric progressive keratoconus (KC), according to a study published in Cornea.

In this prospective cohort study, researchers evaluated and compared the 5-year efficacy and safety of the epi-off and the A-epi-on CXL procedures performed between September 2008 and September 2014 in consecutive pediatric patients with KC. Boys (n=36; 55.38%) and girls (n=29; 44.62%) were included for a total of 78 eyes. Epi-off CXL was performed in 46 eyes and A-epi-on CXL was performed in 32 eyes. Postoperative results were analyzed according to the standard follow-up protocol: at 1, 7, and 30 days after surgery, every 3 months during the first year, every 6 months during the second year, and once a year thereafter. At each follow-up examination, researchers obtained data for manifest refraction, uncorrected visual acuity, best corrected visual acuity (BCVA), slit-lamp examination, and Scheimpflug imaging analysis.

Progression of KC was halted by both the epi-off and A-epi-on CXL procedures, with no statistically significant differences between groups in uncorrected visual acuity, BCVA, sphere, cylinder, steep keratometry (K), and pachymetry. Only 3 patients experienced progression, all of whom were in the A-epi-on CXL group. There was no loss of BCVA lines in the epi-off group, but there was a loss of BCVA lines in all 3 eyes that progressed in the A-epi-on group. Flat, steep, and maximum K did not have significant changes at 12 or 60 months postoperatively in the A-epi-on group, but there was significant flattening of all 3 variables at 60 months with epi-off (0.77±1.41 D, P <.001; 1.02±1.85 D, P =.023; and 1.67±2.22 D, P <.001, respectively). There was also a significant decrease in pachymetry in only the epi-off group (24.40±28.87 µm and 16.67±26.20 µm at 12 and 60 months postoperatively; both P =.001). A significant decrease in anterior elevation values was found in the epi-off group at 60 months follow-up (4.42±5.42 µm, P <.001) but no significant changes in anterior elevation values were found at either 12 or 60 months of follow-up in the A-epi-on group.

“Although epi-off procedure seems to be more effective than A-epi-on procedure, it is important to remember that KC progression in children occurs approximately in 80% of the cases, and in both procedures, the progression was halted in more than 90% of the cases,” the authors said. “It seems that epi-off CXL is more aggressive in flattening K readings when compared with A-epi on procedure, and maybe, this fact should be taken into account when thinking on the desirable effect on the cornea and the risk of progression in each patient.”


Henriquez MA, Hernandez-Sahagun G, Camargo J, Izquierdo L. Accelerated epi-on versus standard epi-off corneal collagen cross-linking for progressive keratoconus in pediatric patients: Five years of follow-upCornea. [published online August 11, 2020]. doi: 10.1097/ICO.0000000000002463