CXL -- Potential Risks and Benefits

[Andrew MacLean]

End of what?

Yes, rapid progression of Keratoconus can be called aggressive. That is a given, but the diagnosis of keratoconus cannot predict whether it will progress rapidly or slowly or even if it will progress at all. I think that the point that was being made is that there is no diagnosis of a form of keratoconus that will turn out to be 'aggressive'.

Would that there were!

In my case my condition progressed very rapidly (even aggressively) for a time then stabilised for years and then progressed rapidly again and stabilised. In the end the thing that led to my needing a graft was not that my KC was aggressive, but that my eyes just stopped accepting lenses.

Andrew

[harker]

Exactly - thanks Andrew.

[Lynn White]

Interesting debate and I will plonk myself down on both sides of the fence here.

Andrew is quite right - there is no official definition of "aggressive" keratoconus.

Harker is quite right - it is a term used very freely by professionals.

A major benefit of CXL is that it has opened up the discussion on keratoconus. We now know that we hardly understand the condition at all. This leads to a multitude of opinions on the subject that will eventually distil into real knowledge.

Going back to this term aggressive. It is generally used when progression can be demonstrated over a period of weeks and months rather than years. As Andrew says, at diagnosis, one can't predict whether it will be aggressive or not.

However, once it is monitored and changes are noted over a very short period of time, that is when professionals start talking about the condition being aggressive.

Lynn

[harker]

Thanks Lynn - Andrew and I were in agreement, however. I think you've confused me with Mousework.

I didn't intend to start an argument. I just wanted to make clear to Carol that there aren't different "types" of KC, as such. One of her replies in the original thread, where she said "I'll find out from the consultant if it's aggressive keratoconus", made me think she might have had that idea.

[Lynn White]

Actually, I wasn't thinking this was an argument - in my mind its a very interesting discussion.

Part of the debate about cross linking is whether to monitor KC to see if it is progressing quickly (i.e. "aggressive") or not. The idea is that, if you are not progressing, then there is no need to do CXL.

The problem then becomes how often do you check the cornea?

Its a really difficult issue because, of course, if it never progresses, you may never need to have CXL. However, if you leave it a while to see what happens and it IS rapidly progressing, the cornea can thin so quickly that by the time the progression is discovered, its too late to cross link. Even if you can still do CXL, the cornea may now be significantly distorted and require more complex contact lenses whereas, with wonderful hindsight, you could have done it earlier and still been able to see with normal contacts or glasses.

Unfortunately, there is no test for KC that can give the answer to this dilemma yet. Additionally, we have no idea of the number of corneas that develop mild KC and never really progress because they generally go undetected. Until we screen a large number of the population and follow them up over years, we really can't find the indicators that will tell us how to recognise an "aggressive case".

This is precisely why some people wish to have CXL as a prophylactic measure. It removes the uncertainty.

Just another thought for consideration: the NHS, in a effort to promote general well being and good health, undertakes a good deal of prophylactic treatment. If you are deemed to be at risk of having heart problems, you may be prescribed statins, apsirin and blood pressure related medication even if you are currently healthy and only have mildly elevated blood pressure or cholesterol. These drugs are usually prescribed for life and are seen as a valuable tool in reducing heart related health problems.

My point is, these drugs are given at the "first sign of trouble" rather than waiting to see if blood pressure or cholesterol levels rise to health threatening levels. The reason for this is that you don't want to wait until irreversible damage is done.

On the other side of this balancing act is the increasing concern that such medication can induce long term problems of their own. Apsirin is the most contentious one as it can cause stomach ulceration and it wasn't that long ago that people were told to take it automatically on a daily basis once you reached 40. Statins can also have undesirable side effects - in some cases, they can cause severe leg cramps.

My father suffered from these and his GP bluntly said "do you want the cramps or the heart attack?" In the end, he reckoned his quality of life was so restricted (as he couldn't even walk to the local shop and back) that it was worth the risk and he stopped using them. Interestingly, his cholesterol didn't go up afterwards.

So, this discussion about CXL is not easy or straightforward. We still don't know what happens to the eye 30 or 40 years after CXL. We do know what happens to an eye that suffers rapidly progressing KC. We don't know how to identify those patients at greatest risk, except that earlier onset is more likely to be associated with more progressive KC.

We did not think, a few years ago, that it was even worth researching how to detect types of KC, as there was nothing you could do about it anyway. All you could do is manage it with contact lenses and then a graft if it progressed beyond a certain point.

What CXL has done is open up this discussion wide open. There is now a very good reason to research types of KC and to do screening, if only to say which people do NOT need CXL.

And again, if CXL has to be repeated 2 or 3 times or even more in a lifetime, compare that with having to take prophylactic medications, every day, for periods of 30 years or more. This is what we do to the older members of our population!

On a slightly off piste point, I know that professionals can be seen as "pushing" treatments.This goes right across the board for all medical conditions, as seen by the blunt approach to my father re statins. This often comes about because professionals see a LOT of patients with the same condition and have to deal with seeing health deteriorate when it could have been prevented by timely intervention. They see a LOT of grief cases - the healthy ones don't come into the surgery. Therefore, there is often an almost palpable evangelical zeal when a new treatment comes along to stop anyone having to suffer through lack of access to it.

People with a condition, though, generally only know their own case in detail. If they manage brilliantly without intervention, they can't see the point in rushing into treatment or, if they have had a bad experience, they can feel the downsides outweigh the general good.

Interesting times...

Lynn

[Anne Klepacz]

Many thanks, Lynn, for setting out the risks and benefits so clearly. For those of you interested in this debate (and within striking distance of London) our next London meeting on 13th October will be including discussion of CXL. So do come along if you can (details in a post I put up a few weeks ago, which may be a few pages back by now!) And on the 'events' ticker on the home page www.keratoconus-group.org.uk
Anne

[Lynn White]

Hi All

Just browsing today and found this link to Pub Med articles on CXL

http://www.ncbi.nlm.nih.gov/pmc/?term=corneal+collagen+crosslinking

There are 337 articles here on cross linking that you might find interesting. Some are pretty academic whereas some are more suitable for general readership.

Some papers set out the risks and benefits and there are many study results: Here are a couple of interesting ones. You can't post more than 3 urls on this forum so I will post again with some more.

Collagen Crosslinking for Keratoconus

Complications of Corneal Collagen Cross-Linking

[Lynn White]

Here are 3 more

Corneal collagen crosslinking for corneal ectasia of post-LASIK: one-year results

Collagen Cross-Linking: Current Status and Future Directions

Corneal Collagen Cross-Linking

Lynn

[Lynn White]

and 3 more

Corneal Cross-Linking and Safety Issues

Safety and Efficacy of Epithelium-On Corneal Collagen Cross-Linking Using a Multifactorial Approach to Achieve Proper Stromal Riboflavin Saturation

Correlation between epithelial thickness in normal corneas, untreated ectatic corneas, and ectatic corneas previously treated with CXL; is overall epithelial thickness a very early ectasia prognostic factor?

This is just a selection of what is out there in academia. You can also search on this website for keratoconus which comes back with about 1400 articles!

Just 10 years ago, you would barely find 20 decent articles with something new to say about the condition, other than contact lens management and grafts.

It shows what advances have been made in understanding the condition but even so, there is still so much we don't know.

The only way to be informed is to seek out information.....

Lynn