Comparison of pulsed and continuous accelerated corneal crosslinking for keratoconus: 1-year results at a single center

Purpose: To compare the clinical outcomes between pulsed and continuous accelerated crosslinking (CXL) for keratoconus. Setting: Hospital. Design: Retrospective comparison study. Methods: Korean patients who were treated for keratoconus between September 2015 and January 2018 at Seoul St. Mary's Hospital were included. Eyes were subjected to pulsed accelerated crosslinking (30 mW/cm²for 8 minutes, 1 second on/1 second off) or continuous accelerated crosslinking (30 mW/cm²for 4 minutes; delivering 7.2 J/cm²). Outcomes were evaluated after 1 year. Results: At 1 year, the 2 groups did not exhibit changes in their corrected and uncorrected distance visual acuity values. The pulsed group (25 eyes in 25 patients) exhibited significantly improved values for sphere (P =.009) and spherical equivalent (P =.033), although no statistically significant difference was observed in the continuous group (20 eyes in 20 patients). All keratometry (k)values (SimKf, SimKs, SimKmean, and Kmax) improved in both groups (all P <.05), although the pulsed group had significantly greater changes in the SimKmean value (P =.036) and the Kmax value (P =.03). Both groups had significantly decreased central and thinnest corneal thicknesses (all P <.001), although the pulsed group had a substantially lower thinnest corneal thickness (P =.017). Corneal densitometry measured using the Pentacam device increased in both groups (all P <.001), with a higher densitometry value in the pulsed group (P =.013). Furthermore, the depth of the demarcation line was deeper in the pulsed group (P =.015). Conclusions: Pulsed accelerated crosslinking might provide better postcrosslinking effects than continuous accelerated crosslinking.