This prospective study compared the safety and efficacy of accelerated transepithelial (A-epi-on) corneal collagen crosslinking (CXL) with standard epi-off CXL in children with progressive keratoconus.
Study design
The authors enrolled 51 patients (61 eyes) younger than 18 years who had progressive keratoconus.
The first group (36 eyes) underwent accelerated epi-on CXL with 30 minutes of riboflavin application (0.25% riboflavin, 1.0% phosphate hydroxypropyl methylcellulose, 0.007% benzalkonium chloride), followed by 5 minutes of irradiation at 18 mW/cm2.
The second group (25 eyes) underwent standard epi-off CXL with 30 minutes of riboflavin application (riboflavin 0.1% solution, 20% dextran 500), followed by 30 minutes of irradiation at 3 mW/cm2.
Scheimpflug imaging parameters were evaluated preoperatively and at 6 and 12 months postoperatively.
Outcomes
At 12 months postop, BCVA significantly improved by 0.09 logMAR and 0.06 logMAR for the A-epi-on and the epi-off groups, respectively (both P=0.05). The UCVA and mean maximum keratometry, however, did not significantly differ from baseline in either group. Despite these nonsignificant differences, the A-epi-on group had mean increases of +0.23 and +0.1 D for steep and maximum keratometry, respectively; whereas the epi-off group had mean decreases of −0.33 and −0.94 D, respectively.
The groups showed similar changes in pachymetry and posterior elevation values. Keratoconus progression—defined as an increase of 1 D or more in maximum keratometry at 12 months postop—was observed in 5.6% and 12% of eyes in the A-epi-on and epi-off groups, respectively.
Limitations
This study was not randomized. There were differences between groups in number of eyes (6 in the epi-on and 9 in the epi-off groups) that had maximum keratometry >54 D, which has previously been associated with a higher failure rate. A follow-up period of 12 months may not have been long enough to truly capture progression in this young population.
Clinical significance
This study adds to literature comparing epi-on and epi-off protocols for CXL, and finds that both protocols are effective in stopping keratoconus progression in children.