Conventional versus accelerated corneal collagen cross-linking in the treatment of keratoconus

This study aims to compare the effect of conventional corneal collagen cross-linking (CXL) with accelerated corneal collagen cross-linking in treatment of keratoconus.

A comparative interventional study was employed.

Participants were consecutive cases of progressive keratoconus receiving either conventional (3 mW/cm(2) irradiance for 30 min) or accelerated CXL (9 mW/cm(2) irradiance for 10 min).

Clinical and topographic parameters were compared between the two groups. Postoperative corneal stromal demarcation line was measured using anterior segment optical coherence tomography.

Clinical and topographic parameters such as corrected distant visual acuity (CDVA), maximum keratometry (Kmax), mean keratometry (Kmean), demarcation line depth were gathered from medical records.

There were a total of 26 eyes with an average follow up of 13.9 ± 6.3 months. Fourteen eyes received conventional CXL, and 12 eyes had accelerated CXL. In the conventional CXL group, CDVA improved significantly (P = 0.021). There was also a significant reduction in Kmax (P = 0.003) and Kmean (P = 0.002). In the accelerated CXL group, no significant changes were found in CDVA (P = 0.395), Kmax (P = 0.388) and Kmean (P = 0.952) postoperatively. A significantly greater reduction in Kmax and Kmean were seen in conventional CXL compared to its accelerated counterpart (P = 0.001 and 0.015, respectively). The demarcation line was deeper in eyes with conventional CXL (P = 0.013), and the depth correlated significantly with the change in Kmean (r = -0.432, P = 0.045).

Conventional and accelerated CXL are effective in stabilizing keratoconus progression after a mean of 12 months. Patients undergoing conventional CXL showed clinical improvement with greater corneal flattening, which correlated with a deeper corneal stromal demarcation line. This current study is the first to report such correlation.