Corneal-cross linking

What is corneal cross‑linking?

Corneal cross‑linking (CXL) is a treatment designed to slow or stop the progression of corneal weakening.

The most common condition treated with corneal cross‑linking is keratoconus. Keratoconus is a condition in which the cornea (the clear front surface of the eye) becomes thinner and gradually changes shape, leading to blurred or distorted vision.

While glasses and contact lenses can improve vision, they do not stop keratoconus from worsening. Corneal cross‑linking is currently the only treatment proven to reduce or halt progression of the condition.

How does corneal cross‑linking work?

The cornea is largely made up of collagen fibres. In keratoconus these fibres are weaker, allowing the cornea to change shape.

Corneal cross‑linking uses:

Riboflavin (vitamin B2) eye drops, and
Ultraviolet (UV‑A) light

Together, these create additional links (“cross‑links”) between the collagen fibres in the cornea. This strengthens and stiffens the cornea, helping it to remain stable.

This process mimics the natural stiffening that occurs with ageing, which is why keratoconus often stabilises later in life.

Who is suitable for corneal cross‑linking?

Corneal cross‑linking is usually recommended for patients who show signs that their condition is progressing, based on:

Changes in vision or prescription, and
Corneal scans showing worsening shape or thinning.

The cornea must be of sufficient thickness for the procedure to be performed safely. Cross‑linking may not be suitable, or modifications might be required, if the cornea is very thin or if there are other eye conditions that increase risk.

To obtain accurate corneal scans, you may be asked to stop wearing contact lenses before assessment:

Soft lenses – usually one week
Rigid gas‑permeable lenses – usually two weeks

Your clinician will advise you based on your individual circumstances.

Where can I get corneal cross-linking?

Birmingham

Nottingham

What are the benefits of corneal cross‑linking?

The main benefit of corneal cross‑linking is to reduce or stop further progression of keratoconus or corneal weakening

In some patients, small improvements in corneal shape may occur, but the aim of treatment is stability, not immediate improvement in vision.

Most patients will still need glasses or contact lenses after treatment

By stabilising the cornea, cross‑linking can reduce the likelihood of requiring more invasive treatments, such as corneal transplantation, in the future.

Are there any risks or side effects?

Corneal cross‑linking is generally a safe procedure, but all medical treatments carry some risks. Possible risks include:

Eye pain, light sensitivity and grittiness while the surface of the eye heals
Temporary blurred vision
Corneal haze (usually temporary)
Infection or delayed healing (uncommon)

Rarely, scarring or longer‑term vision changes can occur. Your clinician will discuss the risks in detail and answer any questions before you decide whether to proceed.

Corneal-cross linking the procedure

Before your procedure:

Eat and drink normally
Wear comfortable clothing
Arrange transport home, particularly if treatment is planned for both eyes or your better‑seeing eye
Stop wearing contact lenses as advised
Arrange help with eye drops if needed in the first few days

What happens during the procedure:

Your eye will be examined before treatment
Anaesthetic eye drops will be used to numb the eye
The surface layer of the cornea is gently removed to allow the riboflavin drops to penetrate
Riboflavin drops are applied, followed by controlled UV light exposure
A soft bandage contact lens is placed on the eye at the end of the procedure

After the procedure:

Following treatment, the eye is often sore, gritty and sensitive to light for several days. Vision is usually blurred at first and improves as the surface heals. The bandage contact lens remains in place until healing occurs (usually 3–7 days)

You will be prescribed antibiotic, steroid and lubricating eye drops.

Recovery and returning to normal activities:

Most people take at least one week off work (longer if both eyes are treated or if computer use is heavy)

You should avoid swimming until advised that healing is complete.

Driving should only resume once your vision meets legal standards and this will be checked at follow‑up appointments.

Contact lenses are usually restarted once healing is confirmed. Glasses prescriptions are best reviewed several months after treatment once the cornea has stabilised