Yes. Cross-linking (also known as CXL, CCR, CCL and KXL) is a surgical treatment for keratoconus.
Corneal collagen cross-linking is a process whereby bonds form between collagen molecules within the structure of the cornea to stiffen its structure. Collagen is the main structural protein of the cornea. Corneal collagen cross-linkage occurs naturally with age and this process can be accelerated using a combination of riboflavin (vitamin B) eye drops and ultraviolet light shone at the cornea. It has been shown to strengthen the cornea. In keratoconus, it appears to prevent progression and may occasionally reverse the corneal bowing to a certain extent.
Cross linking was first developed in Germany in 2000 and clinical trials started the same year. In Italy, this has also been successfully performed since 2002. The procedure has been in routine use in Europe for a number of years with trials showing greater than 95% success rate. Results from an Australian study published in 2008 showed stabilisation in all treated eyes, and a slight correction in visual acuity in most patients.
The aim is to stabilise the cornea and prevent progression of the keratoconus. In a small portion of people, there is a slight improvement in the shape of the cornea and hence the vision but this is not guaranteed.
Other options include corneal ring segment inserts (Intacs or Ferrara rings), or topography-guided laser only to remove slight irregularity (not to remove prescription) and phakic implants. These are for people with stable keratoconus
However, keratoconus typically progresses up to the age of 30 necessitating changes in contact lenses and ultimately it is possible that contact lenses are no longer effective in restoring sight.
The only option is then to consider corneal transplantation (replacing the central cornea with donated corneal tissue). This is a major surgical procedure on the eye needing life long review with a risk of 1 in 500 of blindness and hence avoided if at all possible.
There are risks transplant rejection, unpredictable visual outcomes, and development of high astigmatism. The advantages of postponing a transplant are many; even following a successful procedure, the mean survival rate of a penetrating transplant is about 17 years (many have to repeat the procedure).
Keratoconus can cause substantial distortion of vision, with multiple images, streaking and sensitivity to light. If afflicting both eyes, the deterioration in vision can affect the patient’s ability to drive a car or read normal print.
It is typically diagnosed in the adolescent years and attains its most severe state by the age of 30 (although this is variable).
Keratoconus affects around one person in a thousand. It seems to occur in populations throughout the world, although it is observed more frequently in certain ethnic groups, such as Asians. Environmental and genetic factors are considered possible causes, but the exact cause is uncertain. It is more common in patients with asthma, eczema and hayfever.