How does corneal cross-linking work?
The cornea is made up of layers of collagen fibres held together by cross-links. Corneal cross-linking works by increasing the number of cross-links between the collagen fibres in the cornea, thereby strengthening the cornea.
Corneal cross-linking uses ultra-violet light and Vitamin B2 (riboflavin) drops to stiffen the cornea. The photochemical reaction between the vitamin B2 drops and UV light increases the cross-links between collagen fibres in the cornea and causes them to bond more tightly. This treatment mimics the normal age-related stiffening of the cornea that occurs from exposure to the sun’s UV rays, which is known as natural cross-linking.
What evidence is there that corneal cross-linking works?
Corneal cross-linking is the only treatment currently available that stops keratoconus from getting worse. Evidence from three randomised clinical trials one year after corneal cross-linking showed success in stopping keratoconus progression in over 90% of treated eyes, with over 45% of eyes also gaining an improvement in corneal shape. Longer term results (up to five years) from a different study suggest a similarly high success rate in preventing keratoconus progression. Vision is better after treatment than before in about 50% of eyes treated with corneal cross-linking.
Other studies have also shown that corneal cross-linking increases corneal strength by up to 300%. Without corneal cross-linking, 20% of patients with keratoconus will eventually require a corneal transplant to restore vision. However, only 3% of patients who undergo cross-linking will require corneal grafting.
Is corneal cross-linking safe?
Corneal cross-linking is safe, however, like all operations, your eye needs time to heal and problems may rarely occur. About 3% of patients will lose some vision in the treated eye s a result of corneal haze, scarring, infection or corneal shape irregularity. In the rare event that the cornea becomes scarred affecting vision, a corneal transplant may be needed to replace the cornea.
Will corneal cross-linking improve my vision?
The aim of corneal cross-linking is to stabilise keratoconus. Some patients may have a modest improvement in both corneal shape and vision. Most patients, however, will still need their glasses and/or contact lenses after treatment to achieve best corrected vision.
Some patients will qualify for laser refractive corneal cross-linking. This treatment involves laser resurfacing (re-shaping) combined with corneal cross-linking. The aim of this treatment is to improve the overall shape of your cornea and reduce the optical aberrations of the cornea, resulting in improved spectacle corrected vision. Patients with early keratoconus may even find that their vision improves enough such that they are much less dependent on glasses and contact lenses. This is a relatively new treatment that has shown impressive results in a select group of patients who meet the strict treatment criteria.
What happens after corneal cross-linking?
At the end of the procedure, your vision will be quite blurry. We recommend that you have someone to drive you home. You will be given antibiotic and anti-inflammatory drops to prevent infection and assist with healing. You will have an appointment 3-4 days after the procedure to have the bandage contact lens removed. If the bandage contact lens falls out before that, please throw it away – do not attempt to re-insert it.
Your eyes will be gritty, watery and light sensitive for the first 48 to 72 hours after the procedure. You will be given eye drops and tablets to help with pain relief. Everyone’s experience of pain is different, with some patient reporting very little discomfort and others describing the first few days as very painful.
Although vision is hazy at first, most patients can return to work after one week. Vision will gradually improve over 6 to 8 weeks and it may take up to 3 months for your refraction to stabilise.
Is corneal cross-linking safe?
Corneal cross-linking is safe, however, as with any operation, problems do occasionally occur. There is a 3% chance of worse vision afterwards due to complications such as corneal haze, scarring, infection or surface shape abnormalities. In the rare event where the cornea becomes scarred affecting vision, a corneal transplant may be needed to replace the cornea.
Will I need to have both eyes treated?
Keratoconus typically affects both eyes. You may therefore need to have cross-linking on both eyes if your keratoconus is progressing in both eyes. Treating both eyes on the same day however is not recommended due to the risks.