Abbreviated UVA-Ribofl avin Corneal Collagen Cross-linking for Keratoconus and Post-LASIK Ectasia

Introduction. To determine the effect of corneal collagen cross-linking treatmenton keratoconus and post-LASIK ectasia particularly after an abbreviated exposure toultraviolet light exposure.Materials and methods. Fifty-one eyes of 34 patients were treated withepithelium-off UVA-ribofl avin corneal collagen cross-linking for either 20 minutesor 30 minutes as part of a US.FDA clinical study. The study involved eyes withkeratoconus but with no prior operation (virginal), patients who had undergone priorintracorneal ring segments, those with keratoconus regression after keratoplasty, andthose with post-LASIK ectasia. We report follow up results from three months to oneyear.Results. In the virginal keratoconus group all 83% of eyes having 20-minute UVAexposure and 75% of those having 30-minute of UVA exposure experienced cornealfl attening or stabilization at 6 months post-operatively with visual improvement inboth groups. The average patient age in the virginal keratoconus group was 34.5years. Seventy fi ve percent of virginal keratoconus eyes of patients under age 40but only 33% of eyes of patients over age 40 experienced statistically signifi cantcorneal fl attening at six months postoperatively. Average vision improved at sixmonths post-operatively over pre-operative levels by -0.0744 logMAR units in the 20minute group, and by -0.0869 logMAR units in the 30 minute group. Post-LASIKectasia patients, with an average age of 58.2 years, had slight overall curvaturefl attening of -0.75D but without visual improvement one year post-operatively. Noone experienced peri-operative complications. Topographic subtraction mappingrevealed variations in the power of the cross-linking effect on different portions of thecorneaConclusion. Cross-linking appears safe. It is effective in most young patientscausing corneal fl attening and can stabilize eyes with post LASIK ectasiabut acts more slowly in older patients. The cross-linking effect may be morepronounced in individuals with darker pigmentation. Cross-linking can produceoccasional very signifi cant corneal fl attening. The cross-linking effect increases withtime