Conventional Versus Accelerated Collagen Cross-Linking for Keratoconus: A Comparison of Visual, Refractive, Topographic and Biomechanical Outcomes

Abstract

Objective:The aim was to compare the visual, refractive, topographic and biomechanical outcomes in patients with progressive keratoconus treated with either conventional or accelerated crosslinking at one year follow up.Methods:It is a prospective, non-randomised interventional study of 76 patients who underwent conventional (CXL; 3mW/cm2 for 30 minutes) or accelerated cross linking (KXL; 30mW/cm2 for 4 minutes) for progressive keratoconus. Baseline and postoperative visual acuity, manifest refraction, corneal topography, pachymetry, endothelial cell density and biomechanical parameters of corneal hysteresis and corneal resistance factor were evaluated and compared.Results:The 2 groups were comparable in terms of uncorrected and best corrected visual acuity and spherical equivalent. Both groups showed no significant increase in K1, K2 and Kmean from baseline at 12 months. There was also no difference between the CXL and KXL group for postoperative corneal topography as well as central and minimal pachymetry up to 12 months. There was a significant increase in both corneal hysteresis (0.62mm Hg, P=0.04) and corneal resistance factor (0.91mm Hg, P=0.003) in the KXL group at 12 months but not in the CXL group. There was no significant endothelial cell loss throughout follow up in both the groups.Conclusion:We have established comparability of the 2 protocols in stabilizing the progression of keratoconus. Our findings also suggested an added biomechanical advantage of accelerated crosslinking at 1 year follow up.

Comparison of Standard Versus Accelerated Corneal Collagen Cross-Linking for Keratoconus: A Meta-Analysis

“…However, other studies have demonstrated that both procedures have a comparable effect in stabilizing keratometry. 51,52 It is of note that typically both SCXL and ACXL are generally preceded with epithelial removal (epithelium-off CXL), although investigations have been conducted to explore the potential influence on clinical outcomes between epithelium-off and transepithelial (epithelium-on) procedures using both SXCL and ACXL protocols. 53,54 In an attempt to try to clarify the potential benefits of CXL, we undertook this current meta-analysis to compare the effectiveness and safety of ACXL in comparison to SCXL.…”

Comparison of High Intensity Accelerated Corneal Cross Linking Protocols in Treatment of Progressive Keratoconus;

“…The decrease in CCT is an indirect marker of efficacy of AXL, confirming compactness of collagen fibrils, apoptosis of stromal keratocytes and improved biomechanical stability 8,9,15 . Hashemi et al 8,9 identified a statistically significant decrease in CCT at 18 months following AXL with 18 mWatt/cm 2 for 5minutes.…”

Accelerated (18 mW/cm2 for 5 Minutes) Corneal Collagen Cross-Linking for Progressive Keratoconus: Two-Year Results

“…In a comparison study between conventional and accelerated CXL, both groups showed a significant decrease in CCT and Thin at 1 month, but the maximum decrease was shown in the accelerated CXL group at 3 months and the increase in corneal thickness was slower during postoperative period in that group. 31 In another study, Razmjoo et al compared these two CXL methods and showed that the Thin was further reduced by accelerated CXL. 32 The use of high ultraviolet intensity may be another reason for the decrease in CCT, Thin and CV seen in our study.…”