Standard corneal collagen crosslinking versus transepithelial iontophoresis-assisted corneal crosslinking, 24 months follow-up: randomized control trial

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To compare the results of standard corneal crosslinking (CXL) and transepithelial iontophoresis-assisted CXL after 24 months follow-up.

Material and 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.


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 ± 14μm after 14 days and 172 ± 16μm 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.


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.

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