title: Standard corneal collagen crosslinking versus transepithelial iontophoresis-assisted corneal crosslinking, 24 months follow-up: randomized control trial.
abstract: OBJECTIVE
  To compare the results of standard corneal crosslinking (CXL) and transepithelial iontophoresis-assisted CXL after 24 months follow-up.
  
  
  METHODS
  Corneal crosslinking (CXL) was performed in a series of 149 eyes of 119 patients with keratoconus I-II of Amsler classification. Depending on the CXL method, patients were divided into two groups: (1) 73 eyes with standard CXL and (2) 76 eyes with transepithelial iontophoresis-assisted CXL. Depending on the group, epithelium removal or administration of riboflavin solution by iontophoresis for 10 min was performed, after which standard surface UVA irradiation (370 nm, 3 mW/cm2) was performed at a 5-cm distance for 30 min.
  
  
  RESULTS
  A statistically significant difference in corrected distance visual acuity (CDVA) was observed between the two groups, with a better outcome in the second group after 6 months (p = 0.037); however, no significant difference was found 24 months after treatment (p = 0.829). Stabilization and regression of keratometry values were achieved in both groups, but standard CXL was more effective. The average demarcation line depth in the standard CXL group was 292 ± 14 μm after 14 days and 172 ± 16 μm in the transepithelial iontophoresis-assisted CXL group. No demarcation line was detected after 1 month and 3 months in 45% and 100% of the eyes in the second group respectively.
  
  
  CONCLUSIONS
  Transepithelial iontophoresis-assisted collagen crosslinking showed to be less effective than standard CXL after 24 months of follow-up, possibly due to a more superficial formation of corneal collagen crosslinks, however the stopping of disease progression was achieved 24 months after procedure.
authors.affiliation: Ufa Eye Research Institute, Ufa, Russia. Gbikbova@gmail.com.|Department of Ophthalmology and Visual Science, Chiba University Graduate School of Medicine, Chiba, Japan. Gbikbova@gmail.com.
authors.forename: Guzel
authors.initials: G
authors.lastname: Bikbova
authors.affiliation: Ufa Eye Research Institute, Ufa, Russia.
authors.forename: Mukharram
authors.initials: M
authors.lastname: Bikbov
mesh_terms: D000293:Adolescent; D000328:Adult; D003094:Collagen / Q000378:metabolism*; D063171:Corneal Pachymetry; D003319:Corneal Stroma / Q000378:metabolism*; D003432:Cross-Linking Reagents; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007478:Iontophoresis / Q000379:methods*; D007640:Keratoconus / Q000188:drug therapy* / Q000378:metabolism; D008297:Male; D018613:Microscopy, Confocal; D008875:Middle Aged; D010778:Photochemotherapy / Q000379:methods*; D017319:Photosensitizing Agents / Q000627:therapeutic use*; D012256:Riboflavin / Q000627:therapeutic use; D014466:Ultraviolet Rays; D014792:Visual Acuity / Q000502:physiology; D055815:Young Adult
chemical_list: D003432:Cross-Linking Reagents; D017319:Photosensitizing Agents; D003094:Collagen; D012256:Riboflavin
keywords: crosslinking; iontophoresis; keratoconus; riboflavin