Iontophoresis corneal cross-linking with enhanced fluence and pulsed UV-A light: 3-year clinical results

PURPOSE: To assess 3-year safety and efficacy of enhanced-fluence pulsed-light iontophoresis cross-linking (EF I-CXL) in patients with progressive keratoconus. METHODS: This prospective interventional pilot study included 24 eyes of 20 patients, with a mean age of 23.9 years (range: 15 to 36 years). Iontophoresis with riboflavin solution was used for stromal imbibition. The treatment energy was optimized at 30% (7 J/cm2) and ultraviolet-A power set at 18 mW/cm2 × 6.28 minutes of pulsed-light on-off exposure, with a total irradiation time of 12.56 minutes. Uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), corneal tomography, and corneal optical coherence tomography (OCT) at baseline and 1, 3, 6, 12, 24, and 3 years postoperatively were evaluated. RESULTS: At 3 years, average UDVA decreased from 0.50 ± 0.10 to 0.36 ± 0.08 logMAR (P <.05), average maximum keratometry decreased from 52.94 ± 1.34 to 51.4 ± 1.49 diopters (D) (Delta: -1.40 ± 0.80 D; P <.05), average coma improved from 0.24 ± 0.05 to 0.12 ± 0.02 µm (P =.001), and symmetry index decreased from 4.22 ± 1.01 to 3.53 ± 0.90 D. Corneal OCT showed demarcation line detection at 285.8 ± 20.2 µm average depth in more than 80% at 1 month postoperatively. CONCLUSIONS: The 3-year results of EF I-CXL showed satisfactory I-CXL functional outcomes, increasing the visibility and the depth of demarcation line closer to epithelium-off standard CXL.