Outcomes of standard corneal cross-linking for progressive keratoconus

Abstract

Purpose: Evaluating the clinical results of standard collagen cross-linking (CXL) in patients with progressive keratoconus. Methods: This prospective study comprised 80 eyes of 53 patients with progressive keratoconus. All eyes were treated by standard CXL with 5 year of follow-up. All patients underwent complete ophthalmologic testing that included pre- and postoperative uncorrected visual acuity, corrected visual acuity, spherical error, spherical equivalent, corneal astigmatism, simulated maximum, minimum, and average keratometry, pachymetry, endothelial cell density and Ocular Response Analyzer (ORA). To evaluate the visibility and the depth of the stromal demarcation line after CXL was using anterior segment optical coherence tomography (ASOCT). The solution used for standard CXL comprised riboflavin 0.1% and dextran 20.0%. ). Iso-osmolar riboflavin solution was used for corneas with thinnest pachymetry above 400 mm (after deepithelization), hypo-osmolar solution was used for thinner corneas (less than 400 after deepithelization). Ultraviolet-A treatment was performed with UV-X System at 3 mW/cm2 for 30 minutes. Results: Mean age was 35.5±6.9 years (range: 15–37 years). Mean preoperative UDVA was 0,4 (SD ±0.15). UDVA improvement observed at the 3-month postoperative time and became statistically significant at the 12-month. All topographic parameters (Kmin, Kmax, and mean K) showed a statistically significant improvement (reduction in steepest keratometry) at 12 months post-surgery. Topographic indices (SAI and SRI) showed minimal improvement. Mean depth of the corneal stromal demarcation line after CXL was 318,5±15,2 mm. Stromal demarcation line was visible for 85% of the crosslinked corneas. Pachymetry at the thinnest point decreased significantly (488±45 preoperatively, to 431±37 mm at 5 years). ORA measurements showed no significant differences in corneal hysteresis (CH) and corneal resistance factor (CRF) before and 1 year after treatment. Conclusion: These results demonstrate that traditional CXL is effective and safe option in stabilizing the progression of keratoconus. There was no intra- or postoperative complications except temporary corneal epithelial defect and haze. Corneal endothelial count remained stable without significant decrease. ASOCT showed the collagen cross linking effects in the stroma. There were no cases of progression after 5 years of epi-off CXL.