Accelerated versus conventional corneal collagen cross-linking in patients with keratoconus: an intrapatient comparative study

Purpose To compare the outcomes of the conventional and accelerated corneal collagen cross-linking (CXL) in patients with bilateral progressive keratoconus (KC). Methods Fifteen consecutive patients with bilateral progressive KC were enrolled. In each patient, the fellow eyes were randomly assigned to the conventional CXL (3 mW/cm(2) for 30 min) or accelerated CXL (ACXL) (9 mW/cm(2) for 10 min) groups. Manifest refraction; uncorrected and corrected distant visual acuity; maximum and mean keratometry; corneal hysteresis and corneal resistance factor; endothelial cell density and morphology; central corneal thickness; and wavefront aberrations were measured before and 12 months after the CXL. Results Manifest refraction spherical equivalent and refractive cylinder improved significantly only in conventional group. Uncorrected and corrected distant visual acuity did not change significantly in either group. Also there was no significant change in the maximum and mean keratometry after 12 months. There was significant decrease in central corneal thickness in both groups which was more prominent in conventional group. Endothelial cell density reduced only in the conventional group which was not statistically significant (P = 0.147). CH, CRF, and wavefront aberrations did not change significantly in either group. We did not observe any significant difference in the changes of the variables between the two groups. Conclusions Accelerated CXL with 9 mW/cm(2) irradiation for 10 min had similar refractive, visual, keratometric, and aberrometric results and less adverse effects on the corneal thickness and endothelial cells as compared with the conventional method after 12 months follow-up. However, randomized clinical trials with longer follow-ups and larger sample sizes are needed.