Accelerated Versus Conventional Cross Linking: Which Eyes See Better In The Long Term?

To compare long term outcomes between conventional and accelerated corneal collagen crosslinking (CXL) for progressive keratoconus.

Envision Eye Centre

Comparative study of 25 eyes that underwent conventional CXL (C-CXL at 3 mW/cm² ultraviolet-A light irradiance for 30 minutes) versus 25 eyes that had accelerated CXL (A-CXL at 9 mW/cm² for 10 minutes), with minimum 24 month follow up. Post-CXL changes including best spectacle corrected visual acuity (BSCVA), root mean square higher order aberrations (HOA), corneal clarity (densitometry), and maximal keratometry (Kmax) were analysed at final follow up. 

Mean follow up for C-CXL and A-CXL eyes were 46.28 ± 14.28 months and 40.64 ± 10.92 months respectively. After C-CXL, LogMAR BSCVA improved by mean -0.07 ± 0.17 (P = 0.14) and HOA reduced by -0.24 ± 0.72 (p = 0.12). In comparison, larger improvements in LogMAR BSCVA by -0.11 ± 0.18 (P = 0.03) and RMS HOA by -0.34 ± 0.61 (p = 0.01) were noted after A-CXL.

A significant increase in corneal densitometry was observed after C-CXL (p < 0.0001) wheras a non significant increase in values was seen after A-CXL (p = 0.07). A significant Kmax reduction by -1.79 ± 2.41 D (p = 0.004) was noted after C-CXL whereas Kmax reduction by  -0.84 ± 2.10 D (p = 0.098) was seen after A-CXL.

In our study, both conventional and accelerated CXL significantly reduced the risk of keratoconus progression. The A-CXL group had better BCVA, reduced higher order aberrations and less disturbance of corneal clarity.