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/cm2 for 8 minutes, 1 second on/1 second off) or continuous accelerated crosslinking (30 mW/cm2 for 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.