Corneal collagen cross-linking aims to increase the biomechanical stability of the layers of corneal stroma by creating and increasing cross-linkage between the collagen fibres. As a result the cornea is strengthened and progression of the condition is halted. In a significant number of patients the ectasia has been reduced, in turn reducing the degree of astigmatism.
This is a new procedure which is still under evaluation but offers the potential to minimise the impact of keratoconus so that patients achieve a stable prescription that can be corrected by spectacle or soft contact lens wear.
How Treatment is Applied
Corneal collagen cross-linking is carried out as an outpatient procedure in the operating theatre under topical anaesthetic.
- The eye to be treated is anaesthetised with eyedrops.
- The area around the eye is thoroughly cleaned.
- A clip is inserted to support the lids and hold the eye open.
- The corneal epithelium is gently removed. A solution is applied to soften the epithelial cells which can then be wiped away.
- Drops of a riboflavin solution are applied to the exposed cornea at regular intervals until the cornea is fully permeated.
- The thickness of the cornea is checked to ensure that the UV light can be applied safely. Ultraviolet A light is applied to the cornea for 30 minutes during which time further riboflavin drops are applied together with artificial tears to keep the eye well lubricated.
- On completion of the UVA irradiation antibiotic eyedrops are applied and a bandage contact lens is fitted to protect the cornea and keep the eye as comfortable as possible while the corneal epithelium heals.
- A protective shield is worn for the remainder of the day of treatment and overnight for the first three nights.
Following the treatment there is some discomfort and the eye is likely to be gritty, watery and light sensitive until the corneal epithelium has healed. This can be helped by plenty of sleep or resting with the eye gently closed in a darkened room. A course of antibiotic and steroid drops is given to ensure the eye heals safely. The bandage contact lens will be removed a few days after treatment.
Further follow up consultations are held at intervals until the treated cornea has stabilised. If both eyes are affected by keratoconus then the second eye can be treated at this stage.
Risks of Corneal Collagen Cross-Linking
Until the corneal epithelium heals there is a risk of infection and the antibiotic drops supplied must be used as prescribed. There may be some corneal oedema following the treatment and this will be controlled by using the steroid drops given.
The ultraviolet A light used is applied in a carefully measured and even pattern over the cornea and the thickness of the cornea is checked to ensure that the irradiation will be absorbed by the riboflavin and will not damage the deeper structures of the eye.