Epithelium-off corneal crosslinking (CXL) is effective in preventing worsening of keratoconus in pediatric patients; however, certain subtypes of the condition may be predisposed to continue progressing despite treatment, reports a study published online in the journal Cornea.1 Crosslinking—which increases the production of noncovalent bonds between collagen fibrils to improve the rigidity of corneal collagen—has previously been demonstrated to prevent the progression of keratoconus in adults.2-4 To date, however, no controlled trials have been conducted on the procedure’s long-term safety and efficacy in children.
Researchers in the Netherlands compiled data from patients under age 18 who underwent an epithelium-off CXL procedure for progressive keratoconus between January 2010 and December 2013 at the University Medical Center Utrecht. The procedure was performed in accordance with the Dresden protocol (30-minute isotonic riboflavin soaking time, 30-minute UVA irradiation, perpendicular emission plane, 370nm at 3mW/cm2). Uncorrected distance visual acuity (UDVA), manifest refraction and Scheimpflug corneal tomography measurements were taken and a slit-lamp evaluation focusing on atopic/allergic eye disease and eyelid abnormalities was performed prior to the surgery and at one, three, six, 12, 24, 36, 48 and 60 months post-operation. Fifty-four eyes of 36 patients were involved.
Results indicated that UDVA improved at all follow-up times with the difference reaching significance during the one-year, two-year and three-year visits. CDVA also improved similarly following the procedure at all time points except the five-year-postoperative visit. Patients also demonstrated improvement in both Kmax and Kavg values: the former improved significantly one year post-treatment with significant improvement throughout the follow-up period. Kavg similarly improved with levels reaching significance at the three- and four-year follow-up visits.
“In our pediatric population, epithelium-off crosslinking can be considered both apparently safe and effective, achieving stable long-term results up to five years,” the researchers report, adding that the prevalence of progression was higher in the pediactric cohort considered than in previous studies performed involving adults, suggesting crosslinking may have different effects in different age groups. Additionally, “22% of the eyes [in this study] had disease progression in terms of increased keratometry readings.” This was attributed to decentralized cone location, which is in line with the fact that cone eccentricity has been identified as a major predictor of Kmax outcome.4
1. Godefrooij DA, Soeters N, Imhof SM. Corneal cross-linking for pediatric keratoconus: long-term results. Cornea. 2016. [Epub ahead of print.]
2. O’Brart DPS, Chan E, Samaras K, et al. A randomized, prospective study to investigate the efficacy of riboflavin/ultraviolet A (370 nm) corneal collagen cross-linkage to halt the progression of keratoconus. Br J Ophthalmol. 2011;95:1519-1524.
3. Hersh PS, Greenstein SA, Fry KL. Corneal collagen crosslinking for keratoconus and corneal ectasia: one-year results. J Cataract Refract Surg. 2011;37:149-160.
4. Wisse RP, Godefrooij DA, Soeters N, et al. A multivariate anaysis and statistical model for predicting visual acuity and keratometry one year after crosslinking for keratoconus. Am J Ophthalmol. 2014;157:519-525