A New Year – A New Outlook: C3-R

Happy New Year to all blog readers!!

At the New Year, I made a decision not to make any resolutions as I never keep them. However, to use political jargon, I did make some pledges:

• I pledged to complete all appropriate forms on time, to keep the reception staff happy
• I pledged to keep up to date with my CET
• I pledged to try and learn something new every week

So after finishing one keratoconic RGP fit, I was surprised when I was told

“ I’ve booked a patient next week wanting to know about C3-R treatment for her eyes�

So for those of you who maybe missed this subject in the journals or who have grey matter (like mine) that is just taking a while to get going in the New Year, here is an overview to C3-R treatment for keratoconus.

Keratoconus is a progressive degenerative ectasia of the cornea, characterised by the formation of a cone on the cornea, an oil droplet red reflex, the presence of Munson’s sign and Vogt’s lines in the cornea.  It is thought to affect 1 in 2000 of the population, with onset usually around puberty.  Usual therapies include spectacles to correct astigmatism in early stages, with RGP and some soft contact lenses, and newer surgical techniques such as INTACS also being used.  At present around 20% of cases progress to needing a corneal graft.

C-3R treatment uses riboflavin drops, a photosensitizer, to cross-link the collagen fibres in the cornea, providing more “anchors� between the collagen strands, thereby increasing the intrinsic strength of the tissue and stopping the bulging of the cornea.

The riboflavin drops are applied to the eye, 1 drop every 2 minutes once the epithelial tissue has been removed. UVA light (wavelength 365nm) is then radiated over the central 7mm of the cornea for 30 minutes.

To date the results have been very promising with virtually all eyes treated showing no further progression. 65-70% of treated eyes are also showing regression of the keratoconus with flattening of the k readings by around 2 dioptres. In some studies 85% of patients report an increase in best-corrected visual acuity. There have been no reported adverse reactions to the retina, lens or corneal endothelium as long as correct protocols are followed.

C3-R is not a cure for keratoconus but is intended to halt the progression to enable better management. Suitable patients are generally:

• Those who have pachymetry readings greater than 400 nm (although thinner cornea’s maybe treated using hypotonic drops)
• Having keratometry readings less than 70D
• Having no corneal scarring
• Not pregnant
• Under 40 years of age

Image of Vogt’s striae, above, reproduced from Kanski’s Clinical Ophthalmology. Reproduced with persmission, Elsevier Health Ltd.

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