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

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

Design: A comparative interventional study was employed.

Participants: 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).

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

Main Outcome Measures: 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.

Results: 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).

Conclusion: 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.