Corneal Cross Linking

What is corneal cross linking?

Corneal cross-linking is a minimally invasive procedure designed to strengthen the cornea and slow or stop the progression of corneal thinning and bulging. It is most commonly performed to treat keratoconus, a condition in which the cornea gradually becomes weaker and more cone-shaped, leading to distorted vision. Historically, keratoconus often progressed during the teenage and young adult years, and many patients eventually required rigid contact lenses or corneal transplantation.

Corneal cross-linking uses riboflavin (vitamin B2) eye drops combined with controlled ultraviolet (UV) light to create new bonds between collagen fibers in the cornea, increasing its stiffness and stability. While the procedure does not reverse keratoconus, it is highly effective at halting progression, especially when performed early. The introduction of cross-linking has fundamentally changed the management of keratoconus, particularly in younger patients, by allowing doctors to intervene before significant vision loss occurs and greatly reducing the need for corneal transplants later in life.

Corneal cross-linking (CXL) is a medical procedure designed to strengthen and stabilize the cornea, the clear front surface of the eye. It is most commonly used to treat conditions in which the cornea becomes progressively thinner and weaker, such as keratoconus or corneal ectasia after refractive surgery. The goal of corneal cross-linking is not to improve vision directly, but to slow or stop disease progression and preserve existing vision by increasing the mechanical strength of the corneal tissue.

During the procedure, riboflavin (vitamin B2) eye drops are applied to the cornea, allowing the medication to penetrate the corneal tissue. The cornea is then exposed to a controlled ultraviolet (UV) light. When the riboflavin is activated by the UV light, it creates new chemical bonds—called “cross-links”—between collagen fibers within the cornea. These additional cross-links reinforce the corneal structure, making it stiffer and more resistant to further thinning or bulging.

There are different techniques for corneal cross-linking. In the traditional epithelium-off (epi-off) approach, the thin outer layer of the cornea is gently removed to allow better absorption of riboflavin. In some cases, an epithelium-on (epi-on) or “transepithelial” technique may be used, which leaves the surface layer intact, though penetration may be less robust. The choice of technique depends on corneal thickness, disease severity, and physician preference.

Corneal cross-linking is typically performed as an outpatient procedure and usually takes about one hour. Recovery involves temporary light sensitivity, irritation, and blurred vision as the cornea heals. While vision may fluctuate during the healing process, the long-term benefit is improved corneal stability. Many patients continue to wear glasses or contact lenses after cross-linking, and some may later be candidates for additional vision-correcting treatments once the cornea is stable.

Overall, corneal cross-linking is an important treatment that helps protect vision over time by preventing further corneal weakening and reducing the likelihood of needing more invasive procedures, such as corneal transplantation, in the future.