UK Keratoconus Self-Help and Support Association
A correspondent to the discussion group, Sajeev, wrote:
I would not denigrate any mode of treatment out of hand, but any new option departing from mainstream methods requires some kind of independent evaluation. I am not sure how this can be achieved with a new procedure, but I believe it is necessary to say that any takers should exercise caution at this stage. The Lombardi clinic is advocating asymmetric radial keratotomy to modify the shape of the cornea, and to prevent further changes as part of the natural history of KC. Radial keratometry (RK) requires cutting non-penetrative slits into the peripheral cornea, attempting to modify the corneal topography by the controlled creation of scar tissue. It was one of the earlier refractive surgery procedures for regular myopia but has largely been superseded by laser surgery, which has drawbacks, but is generally accepted to be more accurate and predictable. Laser refractive surgery procedures are deemed to be generally unsuitable for KC because of the already thin cornea and unstable topography. RK has been tried previously for KC, and I don't think the results could be called encouraging. Presumably the Lombardi clinic is carrying out these procedures in a modified way.
The Lombardi clinic web site is highly disparaging about the alternative well established treatment modalities. The comments about contact lens management and corneal transplantation for KC should not be taken as reliable information by the KC self help group.
Contact lens management
Exacerbation of the condition
Any minor problems with the mechanical actions of rigid contact lenses on the cornea pale into insignificance when compared to anything caused by surgery, including RK. Some degree of corneal scarring occurs as part of the natural history of KC. It is virtually impossible to prove exacerbation by rigid lens wear because very few people would agree to leaving even moderately advanced KC uncorrected, so there just is not a non contact lens wearing group to be compared with the lens wearing group. Occasionally people with KC leave one eye uncorrected over a long period, and these eyes are not always scar free. Conversely, there are cases of nearly perfectly clear corneas after many years of rigid lens wear.
It is true that contact lenses are a barrier to oxygen, but many well controlled scientific experiments carried out by responsible clinical scientists have shown maintenance of a healthy level of corneal metabolism with RGP contact lens wear. The great visual advantages of contact lens wear in KC easily outweigh the minor reduction in corneal metabolic activity. There is no evidence that contact lenses act as a suction pump, with the implication that this makes the cornea more distended. Rigid contact lenses are being used to reduce normal regular myopia, a procedure called orthokeratology (OK), but it is reversible: the effect lasting a few days at the most.
Everyone is, or should be, aware that corneal transplants have potential problems, but that is not a reason to not proceed when contact lenses are no longer providing a successful solution. Data relating to the success of transplants is not clear, simply because it is difficult to define a successful outcome. The great majority of keratoconus indicated transplants (95 or 96%) survive five years, but this does not mean they fail at this point. Survival means that the new cornea remains clear, defining success is a more complex issue. The fact is that keeping a track on follow up is more difficult than is commonly thought, so a percentage that survive 10 years, or 15 years is not exactly known. However, I personally know dozens of people whose transplants have survived over 20 years, and they are still going strong. The current thinking in every institution with which I am connected is that the chances of a favourable long term outcome are far higher than the chances of a poor outcome. The Lombardi clinic cites a report in an Italian congress in year 2000 suggesting the survival is on average only 10 years. I'll try to check that out, but it hasn't come up in any coffee time discussions I have joined.
Post transplant corneal astigmatism
It is true that post transplant corneal astigmatism remains a problem, and it can be as much as 12.00 dioptres or more. Spectacles, rigid corneal contact lenses, or maybe a combination of both correct most post transplant astigmatism very effectively. A transplant is not a contraindication for contact lens wear. There may be difficulties fitting RGP corneal lenses to a highly astigmatic cornea, but scleral lenses correct post transplant astigmatism if it is over 20.00 dioptres and can be fitted to virtually any corneal topography. Some further refractive surgical procedures are also commonly used. In any case, even quite high post transplant astigmatism is usually a considerable improvement over uncorrected pre-op KC, unless the transplant has been carried out at an early stage of KC.
It could be that the procedures referred to as alternatives have some applications, but they should not be promoted by overstating clinical drawbacks of contact lenses or by further confusing the issue of corneal transplant outcome.