What is Collagen Cross Linking?

The human cornea consists of a number of layers of which the stroma is responsible for strength. The stroma consists of millions of collagen fibres in close contact with each other. Cross-linking is a medical procedure that combines the use of ultra-violet light and Riboflavin eye drops.  During cross-linking vitamin B2 is dripped onto the cornea and then exposed to ultra-violet light. The UV light light catalyses a chemical reaction which  leads to the formation of bonds between collagen molecules or collagen cross-linking.The Avedro KXL Accelerated Cross-linking procedure is performed in minutes, while traditional procedures typically take one hour.



Why you should consider corneal collagen cross-linking if you have keratoconus

Keratoconus is a progressive condition that starts as a teenager and gets worse into the 20s and 30s. The progression of keratoconus leads to increasing bulging of the cornea causing increasing astigmatism and worsening vision. As keratoconus progresses it becomes increasingly difficult to correct the patient's vision with glasses, and toric or hard contact lenses are required. As we age the tissues in our body form natural cross-links. This same age related cross-linking occurs in the cornea, which is why it is unusual to see progression of keratoconus in patients after the age of 40. Unfortunately, the changes that happen in keratoconus patients up till the age of 40 are irreversible. In severe cases this can lead to the need for corneal transplantation. Collagen cross-linking is currently the only effective treatment that prevents progression of keratoconus and performed early enough avoids many of the problems associated with keratoconus.

Ophthalmologists have seen a marked increase in the prominence of corneal collagen cross-linking as a treatment strategy for progressive keratoconus and post-lasik ectasia. This interest has arisen from a body of evidence documenting the biomechanical and cellular changes induced by cross-linking. The findings of this research provide a rationale for its use in keratoconus to retard the progression of this disease.  A rapidly growing number of clinical reports suggest a consistent stabilising effect of cross-linking along with a variable improvement in corneal shape and visual function in some patients[1].   As a treatment the first aim of cross-linking is to reduce and stop keratoconus in the early phase of the condition, and to prevent the progressive vision loss that occurs which can lead to corneal transplantation.

[1] Grant R Snibson FRANZCO; Collagen cross-linking: a new treatment paradigm in corneal disease – a review; Clinical and Experimental Ophthalmology 2010; 38: 141–153 doi: 10.1111/j.1442-9071.2010.02228.x


Corneal Collagen Cross-linking at Moorfields Eye Hospital

Mr Angunawela offers cutting edge high fluence Avedro Collagen Crosslinking. The main advantage of this technology is that the treatment takes just a few minutes to perform on each eye making the whole experience more pleasant. Conventional non-Avedro treatments take up to an hour for each eye.

Based on NICE guidelines, all treatments are performed after epithelial removal. There is currently very little convincing evidence that epithelium on procedures are as effective using available technologies.


Why you should consider having cross-linking combined with laser epithelial removal

Keratoconus causes progressive bulging of part of the cornea that leads to increasing astigmatism and worsening vision. Whilst some patients notice an improvement in their vision after cross-linking and a reduction in astigmatism, this is usually not very marked. These changes occur due an overall flattening of the cornea after cross-linking. By using a laser to remove the epithelial layer before performing cross linking it is possible to preferentially flatten the bulging part of the cornea, thereby causing a greater reduction in astigmatism after the cross-linking procedure. This leads to a better correction of vision. It is not possible to do this by simply scraping the epithelium away which is the common practice.


What the National Institute for Clinical Excellence (NICE) say about corneal collagen cross-linking

NICE is the national agency that evaluates medical technologies and treatments to ensure that they are safe for patients. Treatments available from the NHS are based on NICE recommendations. Corneal collagen cross-linking was first developed in the late 1990's and is now widely used as a treatment for keratoconus.

Click the Link to read the latest NICE guidelines for cross-linking


To arrange a consultation with Mr Angunawela for corneal collagen cross-linking at Moorfields Eye Hospital or to assess your keratoconus please complete the form and we'll get in touch with you.

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