Keratoconus is a corneal ectatic disease responsible for a loss of visual acuity when the steepening increases. Corneal collagen crosslinking (CXL) is a procedure that appears to halt or slow down the progression and avoid the visual impairment. However, such a technique requires the epithelium debridement, wich can be responsible for severs complications.

This study evaluate the safety and efficacy of transepithelial corneal crosslinking with oxygen to halt or slow down the progression of keratoconus. Such a procedure avoids the epithelium debridement and the related complications.

Keratoconus is a common bilateral progressive corneal ectatic disease causing visual impairment by inducing irregular astigmatism and corneal opacities. This disorder typically begins during teenage years. Patients with severe forms may need a corneal transplantation. The CXL procedure, described in 1998, allows to halt or to slow down the disease progression and may avoid other surgeries, e.g. transplantation. This technique creates links between collagen fibrils in order to rigidify the corneal stroma. The corneal stroma is soaked with a riboflavin solution (vitamin B2) before being exposed to ultraviolet-A (UVA) radiations. In the current standard CXL, the central corneal epithelium must be debrided to allow the penetration of riboflavin into the cornea, with a risk of side effects, such as pain for the first two post-operative days, temporary loss of visual acuity during the first three months, and serious complications such as infections and stromal opacity due to corneal scarring Transepithelial crosslinking is a non-invasive technique in which benzalkonium chloride is used to enhance the penetration of riboflavin into the cornea. To improve the reaction, a device provides oxygen to the corneal surface. The transepithelial technique could allow intrastromal riboflavin diffusion, while keeping the corneal epithelium on, conserving the efficiency of the standard procedure without the complications induced by epithelial debridement.

Patient with progressive keratoconus will be included and treated with the transepithelial procedure. The follow-up will last for one year. Every follow-up visit will evaluate the security of the procedure and its efficacy to stop or slow down the progression of the disease. Interrogatory and slit lamp examination will be performed to investigate the potential adverse effects of the procedure.

Inclusion Criteria:

• Be at least 18 years of age
• Provide written informed consent
• Diagnosis of progressive keratoconus
• Best corrected visual acuity between 0,05 and 1 decimal scale
• Willingness to follow all instructions and comply with schedule for follow-up visits.
• Social security insurance or equivalent.

Exclusion Criteria:

• Hypersensitivity to local treatment
• Corneal pachymetry < 400 μm
• Non progressive keratoconus
• Aphakic eye or eye with cataract implant without UV filter
• Concomitant corneal disease
• History of corneal surgery
• History of crosslinking treatment
• Pregnancy or lactation
• Juridical protection