Mini A.R.K Database

[Prue B]

Statistics can be used to show varying "facts". They can be scewed to prove your mindset. This is not in most cases fraud, but is more if you believe something, or want to believe something you can read statistics differently than a person who does not beliieve it. I can remember a study that showed. 95% of Australians who had heart attacks ate vegemite as children. So should I go out and stop eating vegemite. Or should I consider what percentage of Australian children ate vegemite as children. 95% would be pretty close to the mark.
Talking about vegemite, the stories from India make me wonder if nutrition and or good eye care slow down the progress of KC. I cannot really see what the eye care I recieved would do to slow it down, but maybe wearing glasses, or lenses means you dont squint quite as mjuch so put less pressure on the eye. Nutrition is self explanitory imo.

[Hari Navarro]

I think that what Prue is saying is very true. We all try our best to understand Keratoconus, we dig and dig for that tiny piece of information that will provide us a cure. The problem is the majority of us are not doctors and here we are pouring over advanced medical journal extracts trying to make sence of them.
Statistics pop up all the time and it very easy, as Prue rightly said, to attribute whatever meaning you like to them.
The often posted 96% success rate following PK is one that I have always had a lot of trouble with. I personally feel that it is misleading to those new to KC but that it is waved to easily as a banner for many a corneal specialist.
I think that the prevalence of keratoconus on the sub -continent is a vast issue that will have any number of factors contributing to it. But it is too easy to say that the fact that many of these people do not use RGP's yet still have scarring - and that this in itself is proof in some part that they do not have such a detrimental affect on our eyes.
I think the squinting issue is overlooked but very important, the added daily pressure on the eye within populations that do not have access to correction should not be underestimated. We on the other hand do have access to these modalities, but what is the trade off? Corrected vision yet possible increased scarring. I know this is debateable but it is an issue non the less.
Diet, climate even altitude have all at one time or another been indicated in the progression of KC, I personally feel that it is a combination of factors.
There is no easy answer - I am originally from New Zealand so maybe some sort of Vegemite treatment might be just what we are looking for

Hari

[jayuk]

Hari

I completely agree with you 100%

The 96% figure used for PK is just utter rubbish and nonsense. More to the point, its even worse when its been given to those that are being recommended the Transplants; as this gives the patient a sense of relief (yet completely false!)

Speaking of research, it would be amazing to see how many KC sufferers have gone through a PK that didnt need it!....Impossible task I guess!!

I beleive that this is where websites like this add there value and allow existing sufferers to ask these very questions!

But we need to get over this mind set in KC that Grafts are the answer....as right now they are far from it until key areas of the treatment and procedure are addressed!

J

[Andrew MacLean]

I'm not sure that I agree that statistics are misleading, but I do believe tha people who want to mislead can use numbers in an irresponsible way.

Somebody once said that statistics lie. I am entirely persuaded that this is untrue, but I have no doubt that liars use statistics!

Andrew

[Hari Navarro]

Statistics are just numbers, they mean nothing untill they are put in context.
They can be exploited and so become misleading. If a percentage appears within an independant medical study concerning the success rate of corneal transplants then that's one thing-- but for it to then appear on a keratoconus educational website, or doctors homepage it's quite another. It may not be strickly true that statistics lie but they can in many instances be moulded into telling half truths.

Hari

[GarethB]

I remember a questions on the statistsics module when I was at Uni.

Basically if you used the wrong statistical model, you actually prved the statistically statistics are completely wrong.

Yes liars use statistics, but is possible that in complete inocense, the wrong statistical model/tool is used and unfortunatly the conclusions drawn are misleading.

It is getting more and more common that a statistician is given the data from the research team to correctly analyse the data. The research team then look at the analysed data from which conclusions are drawn.

[Hari Navarro]

To avoid diluting the point I'll ask the question straight:
Is the 96% success rate for PK misleading? It is not used in isolated instances and is the first statistic that many come across when first researching Keratoconus. If it is misleading then why has it not been universally challenged by the Keratoconus community?
Many that I have spoken to have found comfort in the fact that if their KC progresses past the point where correction is useful then they can have graft with only a tiny (4%) cause for concern. This is just straight out not true - Education of the true characteristics of any of the treatments we choose is essential.
Ask a corneal surgeon what it is he uses to judge success and then ask a patient, I'm sure the two will differ.

Hari

[jayuk]

Hari

The 96% value given is incorrect as far as I can see; and those that have a keen interest (both patients, sufferers,etc) are probably more real to this than the average KC sufferer.

But I think you are also answering your own queston and further addressing your concerns.

What a patient deems successful; a consultant may not

Consultant :
Clear Cornea
No signs of Rejection
Sutures Aligned
No Keratoconus

Patient :
Comforable
Improved VA (most likely 6/12 and above)
Can Function
No Pain
Has there life back

As far as changing things and perception...this does take a while.....none of us here are Michael Knight and I am afraird in this case "One man CANNOT make a difference".

Which goes back to my initial comment that its web sites like this that can make the difference and allow sufferers to air their concerns.

Rather than be flippant and out right say "Oh no Grafts are bad bad bad no no no; this is some wild global conspiracy, all Consultants are barbarians etc"; as a select few other sites do; there needs to be reason and understanding as to why a PK is NOT the solution for the large majority of KC patients.

However, there also needs to be a reason WHEN and WHY PK is the right treatment!

Sadly, it seems many are falling into the the prior rather than the latter!

You need to understand that a Optham stems from a Medical and Surgical background therefore majority of them are keen to address the KC via surgery! This is a global issue...and one that can only be addressed via information, experience and dilligence

J

[Andrew MacLean]

It can be not misleading and still not significant. This is the difference between data and statistics.

Data are numbers. they become statistics after the application of a statistical examination, or analysis.

for my part I'd be interested in the population that was studied, how many eyes were included in the study and what controls were applied.

My question is this "Is the claim statistically significant?" As nobody has ever seemed to suggest that it is, my conclusion is that while the claim may be accurate it is based on a population either so small or so selective that it is probably impossible to base any conclusions on it.

Andrew

[GarethB]

Andrew,

You have hit the nail on the head there.

The same applies to C3R, it has an extremely high success rate, but the population of KC people who have been treated have had to have met strict selection criterea. There for the sample population for statistical analysis is very small, but of that small population the changes in visual aquity are statistically significant as are the changes in the K values.

The research into C3R has been very acreful to avoud suggesting that it is a cure for all cases of KC whcih was once the claim for grafts.

To be honest I think PK is yet another management startegy which has high success as long as certain criteria are met prior to surgery as is the case with C3R and what is happening more and more with grafts. Penetrating or partial are now being determined by several factars regarding the patient as opposed to the preferred technique of the surgeon.