Efficacy And Safety Evaluation Of UVA/riboflavin Crosslinking For Late And Thin Cornea Keratoconus

Objective:Riboflavin/UVA mediated corneal collagen cross-linking improve the cornea biomechanical properties through enhancing the crosslink among the corneal collagen fibers. The treatment impede the progression of keratoconus and achieve the desired clinical outcome in patients with advanced keratoconus. Previous studies have shown that during collagen crosslinking treatment, no UV light derived damage was found in the coneal endothelial cells, lens and retinas in the corneas with thickness more than400μm. This study was conducted to evaluate the efficacy and safety of UVA/riboflavin corneal crosslinking in late keratoconus cases with cornea thinner than400μm.Methods:18eyes of14keratoconus patients with corneal thickness less than400μm were recruited in the study, and rule out other eye diseases.3days before the operation, antibiotic eye drops used to the eyes. Corneal epithelium of central8mm was removed mechanically under topical anesthesia, then hypo-osmotic riboflavin was applied until corneal thickness reached over400μm. Then standard UVA/riboflavin corneal crosslinking was applied. The corneas were irradiated with a370-nm VUA for30mins (irradiance3mW/cm2, dose5.4/cm2) at a distance of5cm from the corneal surface,0.1%riboflavin hyposmotic solution was dropped onto the central cornea every3mins. BCVA, apex K value, corneal thickness, endothelium and lens changes were examined and recorded.Results:Corneal epithelium was recovered within1week,14eyes within5days. Corneal haze was found in all patients and vanished in2to6weeks. BCVA was4.77±0.09before treatment and4.81±0.05,4.83±0.05three and six months after. Apex K value was56.29±7.33D,52.42±5.76D and48.12±6.6D before,3months and 6months after treatment respectively. Corneal thickness was317±33μm,408±66μm,381±71μm and354±34μm before, after swelling,3months and6months after crosslinking. Endothelium was3070±201/mm2,2901±218/mm2and2933±216/mm2prior treatment,3months and6months after.Conclusion:During six months’follow-up after operation, the corneal thickness of the group was in stable state, BCVA was higher than that of preoperative slightly, corneal K value decreased, there was no obvious difference of corneal endothelium and the endothelial cells morphology. Our study shows by using hypo-osmotic riboflavin to swell thin cornea, UVA/riboflavin corneal crosslinking is safe and effective in the treatment of late keratoconus.