A monocentric, parallel-arm, prospective, randomized therapeutic trial that compares the efficacy of two curative keratoconus treatment techniques by cross-linking collagen (accelerated conventional technique or iontophoresis). The primary endpoint will be the depth of the demarcation line measured by confocal microscopy and OCT at 1 month. This line represents the limit depth between treated and untreated stroma.

A two-arm, parallel, open-label, prospective, randomized therapeutic trial comparing two management strategies. The goal is to describe and compare, thanks to in vivo confocal microscopy and optical coherence tomography (OCT), the structural modifications observed postoperatively on evolutive keratoconus treated by cross-linking of collagen in accelerated procedure and iontophoresis. The study will be monocentric and will take place in the ophthalmology department of Clermont-Ferrand University Hospital. Patients will be recruited through consultation dedicated to keratoconus (The ophthalmology department of Clermont-Ferrand is one of the 9 French centers of expertise for this pathology). Inclusion will be offered to all patients over 18 years old who meet the scalability criteria and who will benefit from a cross-linking procedure. Blind randomization will be performed between iontophoresis and accelerated procedure. The dates of the visits will be fixed, with a preoperative evaluation, and a follow-up follow-up on 6 months with controls at 1 month, 3 months and 6 months. Confocal microscopy imaging and OCT will be performed during the preoperative visit and during visits at 1 month, 3 months and 6 months.

Inclusion Criteria:

• Pachymetry greater than 400μm

Topographic criteria for keratoconus evolution:

Variation over a period of 6 months of the following parameters:

An increase equal to or greater than 1D of maximum keratometry (Kmax) And / or an increase in mean keratometry (Kmean) greater than or equal to 0.75D And / or an increase in the difference between the most arched and the least arched meridian (Kmax-Kmin) greater than or equal to 0.75D And / or a decrease in corneal central thickness greater than or equal to 2%

Exclusion Criteria:

Ectasies post LASIK Pregnant women breastfeeding Major corneal opacities Absence of consent to participate in the study No affiliation to social security or State Medical Aid (AME) or Universal Medical Coverage (CMU)

No masking