Kerasoft IC and K3 Trial

[Andrew MacLean]

Lynn

Thank you for that most lucid account of the importance of clinical trials.

All the best.

Andrew

[private104]

You are welcome Gareth. Truth is I don't think I could have coped with this year without the support you and Andrew and Lynn and the others have given me.

Andrew - I was in earlier and saw pepe's post. I think you were right to edit it, although I didn't know you could do that. I think you are very patient. I'd have started 'editing' way back .

I am very interested in this string. I know that I may not always be able to manage with my hard lenses and it is good to know that there will be other choices.

AJ

[Andrew MacLean]

AJ

The moderators in this forum are generally reluctant to intervene in exchanges between members, and we try not to step in too soon. Sometimes we can be accused of erring on the side of being a little laissez faire.

That said, everybody who signs up for the forum makes certain undertakings and this includes an agreement that unacceptable posts will be removed.

Thank you for your understanding post. It is because this string still holds the capacity for offering informed support that we have not locked it.

Andrew

[pepepepe]

Its not true I insulted anyone, if the post was not removed people would know this.

And besides Lynn replied to me. Also I showed a post where two very opposing answers to the question I put to Gareth.

To reply to the post I copy below, are we saying that no measure can be put on Kerasofts claims other than the company it self ? There are other Soft lenses for KC and also other new contacts, why arn't they discussed the same by those who say they are not biased ?

A forum is to discuss by the many and that's what I am doing, when I ask why their is a post code lottery (for example) and why it continues, its the UK charity I must ask, why that has to be censored I don't know, but its not charitable.

I copy below Lynns last post for conveniance.

You raise an interesting point there Pepe, about the difference between clinical and scientific trials.

In my post above, I refer to the trials I do as clinical and I am a (clinical) keratoconus consultant (not a "sales" consultant). I referred to Gareth's contributions as "scientific" because he approaches his reporting in an unbiased scientific manner, equally listing pros and cons. I referred to adding to scientific knowledge, because his (and others in the trials) observations supplied information that is useful for designing future clinical/scientific trials. Ideas for scientific study do not come out of thin air. Work in the field tends to go hand in hand with scientific study and compliments each other.

A randomised double blind trial to explore whether Silicone Hydrogel contact lenses correcting keratoconus are "better or worse" than other KC lenses would be difficult to design. Such scientific trials have to face the difficult task of hiding from the subject and the contact lens fitter what lens is being worn in each eye. Only the researcher knows which eye is getting which lens. So we can immediately eliminate comparing them to RGPs/sclerals/piggy backing/hybrids and so on as it is patently obvious which lens is in which eye! In fact, for the same reason, you cannot do a randomised double blind on sclerals vs RGP, Synergeyes vs RGP and so on. Even if you tried to do a RGP vs RGP of different design, this would be difficult as the size of the lenses would most likely be different and the fitting method would be different. Thus the fitter would soon get an inkling of what lens they were fitting to each eye.

So you are left with comparing soft lens with soft lens. OK, you may think one soft lens looks much like another but all the soft lenses for keratoconus on the market at the moment all have different designs and materials which mean the fitting methods are different, so the fitter cannot remain ignorant of which lens he is fitting. Added to this is the fact you are fitting keratoconics who are all different to each other and usually have one eye markedly different to the other. Randomised double blind contact lens trials in the normal population rely on fitting Lens A to the right and and Lens B to the left and comparing the performance. So how can we do this with a keratoconic who may only have KC in one eye? Or a graft in one eye and INTACS in the other?

OK then, perhaps we split the subjects into two groups and have one set of fitters fitting one type of lens and another fitting the other and compare the group results. Subjects are then allocated to the groups randomly. But without any sort of control over the groups, one may end up with a lot more PMD and post grafts in one group and classical KC and subclinical KC in the other. Any one individual's eye may have unique chracteristics, so we are not comparing like with like.

So perhaps we screen the subjects first to try and get the two groups as similar as possible. Apart from this being almost impossible (I have yet to see any two keratoconic eyes that are identical enough for such a study) you would end up comparing lens performance on a very small sample of keratoconus subjects and although the results may be scientifically interesting - after a period of a couple of years or so, you would be no nearer knowing if the new lens type would benefit the wide range of KC out there than you were before.

Double blind trials explore, scientifically, products that have already been designed and manufactured. They cannot create products. Initial research has to invent products and make sure that they do not cause harm BEFORE they are entered into double blind trials and there are government controls in place to ensure this.

What can be done, once the material the lens is made from has passed required safety tests, is compare its performance against other materials in a double blind trial as long as the design is reasonably similar. As I have said before, the material from which KeraSoft is made is currently undergoing several double blind scientific trials. These are not my studies, however, and the the results will take time to work through the peer review system.

The clinical trial I was conducting concentrated on the material/design combination and how it performed and also provided case studies to use as an aid to creating fitting guides for practitioners. Any company producing ANY kind of contact lens conducts these sort of trials. The KeraSoft3 trial incidentally led to the design of the new KeraSoft IC (Irregular Cornea) as it became clear that there are many complicated corneas, many post surgical, which require a more customised lens. Those for whom the KeraSoft3 lens did not work are now being fitted with KeraSoft IC in a new set of trials. This lens design customises the back surface to better fit very irregular corneas and I have been looking at different methods of customisation and comparing how successful they are.

The information gained from such trials feeds back into the pool of scientific knowledge and will be collated and presented in journals for peer review in the future - not as double blind trials but as scientific papers based on the data gathered. This information may be as diverse as corneal shape types, aberrations in KC eyes, dry eye problems or fluctuating vision after CXL - none of which may have any direct connection to contact lenses.

It is in this way that clinical trials designed to aid manufacture of new contact lenses adds to scientific knowledge and very often inspires scientific trials which clarify and refine that knowledge.

[Andrew MacLean]

pepe

I am not going to get into an exchange with you about what you said about Lynn. You were notified that your post was unacceptable, and after consulting with the other moderators the decision to remove the text was mine.

You were notified that in the event of any further personal attacks or insults against other users you would be suspended. That caution stands. People on the forum have been very patient with you, but just as there are boundaries to acceptable discourse, there are limits also to the patience of other users.

I hope that this string can continue to offer supportive information to people who are trying to find their way through the labyrinth of lenses. If you are not prepared to allow that to happen, the topic can be locked.

Andrew

[rosemary johnson]

Getting back on topic ......
I'm interested indeed to read that one of the findings of this trial, with Gareth at least, is the length of time it takes for an eye to adjust away from having been wearing hard lenses.
I might have expected a few days, but a month surprised me.
Is this coming outof the study as something common to many/most of the subjects, or does it vary a lot between people? - and does the fitting of the hard lens (tight/less tight/more tight) make a difference?
And have you had the same finding with someone moving to the erasoft lenses from sclerals as from corneal lenses?
Rosemary

[Lynn White]

Hi Rosemary,

The difficulty of coming out of RGPs is something well known about - and not just for keratoconics. Many years ago, when soft lenses were new and almost everyone wore RGP lenses, it was a big issue. We were taught at Uni to tell patients to leave lenses out for a fortnight before they had a test for glasses and I still hear that now, though to be honest I never saw the point. Do you wait 2 weeks before you put your glasses on? No, you come home, take your lenses out and put them on.

The reason for this somewhat apparently illogical idea is that the normal cornea rends to do the bulk of its unmoulding in the first 2 weeks of discontinuing wear. The corneal shape often ends up where it began having done a few "flip flops " in between. Why? Because of mechanical compression. The early rigid lenses particularly did not really match corneal shape and were fitted steep, so in essence bent the cornea to their will. Once released from this restriction, the cornea would fluctuate in shape before settling.

Fast forward to recent years, and modern RGPs have much better shapes and are fitted much better, the aim is to get minimal impact on the cornea, so with normal eyes, there is often quite a short "demoulding time" if any. However, that is with normal corneas. Keratoconic eyes are a different kettle of fish. When we talk of KC, we talk of the steepness of the cone. This tends to give the impression that its just the front bit getting more pointy but its more than that. If you pinch your arm, say, you pull up part of the flesh but simultaneously "dent"the flesh each side of the pinch. In the same way, keratoconic corneas not only have very steep areas, but also very flat areas and it is this factor that makes fitting with RGPs sometime so difficult. They have a regular back curve and either skate all over this weird shape or bed down and mould the cornea to ITS shape. This can happen fairly easily because KC corneas are thinner and softer than normal ones.

Thus moulding is an issue with RGP lenses. With Gareth, his demoulding wasn't that much of a problem in itself.. just that it simply took so long to completely stabilise. It meant that his vision was around 6/9 or a bit less for some of the time and the difficulty was working out when it was finally stable. As I said, his lenses were fitted really well but in essence his cornea is not that regular!

Sclerals... well the issues are less of a problem in that the lens surface vaults the cornea. However, depending on the fit, type and sensitivity of the cornea, there can be oxygen transmission issues and corneas that have been subject to oedema can also take a while to settle down.

I have found that with a cornea that has been well and truly squashed by an RGP, getting decent vision at first out of a KC soft lens can be a bit of a challenge and my advice would always be to do one eye at a time. However, patients are notoriously "impatient" and often just go for it for both eyes.

Lynn

[Andrew MacLean]

Lynn

That is really interesting. Can I ask you to develop your 'pinch' metaphor a little? When we were younger, pinched skin would snap back very quickly on being released; now (for me at least) it seems to rather like the new shape into which I have pinched it, and its return to 'normal' is a far more leisurely affair.

My question; is age an issue with 'demoulding'?

Andrew

[GarethB]

In addition to Lynns post, my right eye is the steepest and was fitted with a toric lens and the left eye is a lot flatter and fitted with a Rose K. The result was the left eye did settle very quickly so through most of the demoulding process I was coping with good vision in the left eye and slightly worse on the right.

This is the sort of information that interested my hospital and they have said they would like to discuss it further as they think thay may have been to premature in dismissing the use of soft lenses.

Regarding other lens types it would be inappropriate for me to discuss them as I have no information on them or experience. I have however been intouch with other contact lens manufacturers to ask if they would allow this group to evaluate their products and all stated that they get there information from the hospital optoms they work with. We do have representatives from other lens manufacturers registered with this forum and there is nothing stopping them from asking for volunteers to try any lenses they are developing.

Only two manufacturers said it is beneficial working with us, one we know about being discussed here and the other we all know for the work done regarding sclerals.

If anynoe else has experience of any otehr lens types it would beinteresting to know how they have helped.

[rosemary johnson]

Lynn

That is really interesting. Can I ask you to develop your 'pinch' metaphor a little? When we were younger, pinched skin would snap back very quickly on being released; now (for me at least) it seems to rather like the new shape into which I have pinched it, and its return to 'normal' is a far more leisurely affair.

My question; is age an issue with 'demoulding'?

Andrew

ANdrew:
If you pinch your skin and it stays pinched, this is a sign of dehydration.
It is oneo f the tests to do on a horse who is off-colour - or after exertions, like a race or a cross-country course, as they can easily sweat out too much water and get dehydrated.
We had a pony at our yard not so long ago who was on medication after an injury in the field and wouldn't drink and it happened to him - very dehydrated for a while.
Yes, skin does lose natural elasticity with age, but it shouldn't take all that long to go back after a pinch.
Rosemary