Kerasoft IC and K3 Trial

[Lynn White]

Now then Andrew.... metaphors can be taken too far hehe!

My metaphor in using the pinched skin was to try and give a more 3D appreciation of the corneal shape i.e. you can't have protrusion or "bulging" (I really do NOT like that word!) without it affecting other areas of the cornea.

However, I do take your point and indeed an ageing cornea parallels CXL to a certain extent so in fact yes, older corneas may indeed de-mould slower than young ones...

Lynn

[rosemary johnson]

Hallo Lynn, and thanks for the detailed answer.
I did know that having a hard lens in does affect the shape of the eye - and remember when I was about 17 a friend on ther receiving end of the advice you mention holding forth with what you say: "I want my glasses to put on when my lenses play up and I've just taken them out - not three days later once my eyes ahve changed shape!" so the 3 days he'd toldher she had to laave the lenses out before he'd test her eyes for new glasses was ridiculous. But it was only 3 days, so I'd no idea it could take so long to unmould.
I'm also well aware that the vision is quite different when I take out my RGP scleral lens from how it is the following day - though have never left a lens out for a monthto try out the full scale of demoulding over that long. Nor even left it out of my own eyes for anything like 2 weeks since I was about 20. Or 1 and hiving a hydrops..... And of course they were PMMA in those days.
I'm guessing that the moulding effect of sclerals will depend on whether they fit truly well clear of the cornea, in which case there's a pinch effect but no central pressure, or whether they fit with central contact zones, as mine have always had in my own eyes, in which case, less pinch but more pressure.
BTW, when you say "RGP", are you meaning "corneal"? - I was reading you as meaning all lenses made of RGP materials, and these days synonymous with "hard" lenses, until you mentioned sclerals specifically.
Rosemary

[pepepepe]

All good laser surgery web sites tell you how long it takes for your cornea to come to its final resting place when wearing contacts, as they need to know what it is so that the laser correction can be accurate. For RGPS its one month or more, for soft lenses its a week or more. Kerasofts pushes back the KC cone (with a use of a band around the lens puching back towards the cornea, thats the trick behind them) unlike other soft lenses so the time is probably more longer an for ordinary soft lenses.

Contacts causes corneal warpage and to do topography with this warpage will not give correct results unless the contact lens is left out long enough. Its well know about, even in contact lens fitting which can be effected.

[Lynn White]

Hmm Pepe..

Laser contact lens sites are not the best place to look to re advice on KC and contact lens wear as they do not laser keratoconics. They deal with normal eyes. Eyes with KC have corneas that are structurally weaker than normal eyes and are thus affected diferently.

For your information, KeraSoft does NOT push back the cone. Neither does best practice RGP fitting, scleral fitting, Synergeyes fitting, hybrid fitting etc. Modern KC lens fitting relies on NOT doing this as it causes more problems than it solves.

And "with a use of a band around the lens puching back towards the cornea, thats the trick behind them" - is news to me. Where did you find this misinformation?

Rosemary,

The term RGP is generally accepted as meaning corneal rigid lenses - usually meaning a diameter of around 9.00mm give or take a bit. As you rightly point out, other lenses ARE made out of RGP material but they have other names/definitions such as Apex, Scleral, semi-scleral and so on.

To clarify, the common usage of the term RGP means a corneal lens of approx 9.00 plus or minus a few mm. However, RGP also means Rigid Gas Permeable as in a hard plastic material that allows oxygen to permeate through it. As such, many different lens designs can be made from this material.

As you also say, scleral demoulding depends very much on the type of fit.

In the end analysis..... demoulding is complete when the topography/spectacle prescription is stable.

Lynn

[Andrew MacLean]

Lynn

How many similar readings would you need before you would decide that a cornea was stable? two, three ...

[Lynn White]

Hi Andrew

Its like ..... how long is a piece of string? Because you don't know exactly what is happening until you start following someone through? Usually, it 2 or 3 measurements. But practically speaking, its when your gut feeling tells you it's right. There are so many factors involved that this really depends on the individual's history!


Lynn

[Andrew MacLean]

In spite of a number of warnings, pepe continued to send posts that were personally insulting of other users.

His posts have been removed and has been suspended.

Andrew MacLean

[GarethB]

Just a quick update on the K3 lenses and the whole demoulding of the cornea so we are going to follow this up a lot more closely. I'm going to see if I get a more moder graphics package than I used to have so I can have a go at animating the process.

Had another trip to London which proved very interesting and as soon as I have the topographies and video I'll post them. Basically the topography shows that my cornea is becoming flatter still and we are now three months with no RGP wear. It raised an interesting question in that how come I see better than 6/6 in a lens that was fitted for a steeper cornea?

For me from a patient perspective this is potentially good news in that useable vision can be obtained and as the eye demoulds vision is not lost too much and life can carry on pretty much as normal. This may be unique to my eyes but as we have seen it in me, from a research perspective I'd go and see if the same was aparent in others. So this I feel is really helping to understand the demoulding process of a keratoconic eye and hence if a patient changes from an RGP to soft lens the process is better understood so the transition can be managed in a controlled strucured way.

My personall theory which I put forward (and I'm still mulling it over so might change my mind ) is that the zone of the lens where all the optical correction is on, that area is thicker than the outer edge of the lens. When handling the lens you can feel this, so I think it is thick enough to maintain much of its shape and tears are filling the gap like they would in an RGP, hence I can see very well.

It has been mentioned to me that in a 'normal eye' that has had an RGP lens on it for 20 years would take upto 3 yeasr to demould. If this is linear and a keratoconic eye follows the same process, then I might be looking at 6 - 7 months hence following this closely to see if it is true or not. So i might be half way through the process.

Still getting better than 6/6 in each eye and I have worn these on one day for 18 hours with no problems.

It was interesting to actually see how a lens moves on my eye and what a graft looks like 20 years on.

Left


Right


So in summary, two places have obtained the same readings from looking at my eyes with the K3 lenses in, cornea is healthy so for me no change from a day to day perspective.

[Lynn White]

Hi Gareth!!

First of all, let me say thank you! You came for a check up but ended up doing your bit as a representative of this group by helping to counsel a fellow keratoconic in my clinic. You did an amazing job in reassurance and missed your train in the process - thank you again.

Now... as to your comments.... this was an entirely interesting visit. I have always felt your RGP lenses were an excellent fit and there was nothing I could see that implied otherwise. So when we were swapping you to KeraSoft, I really didn't see an issue with "demoulding" - I really thought a couple of weeks and you would be settled. But as you say, the measurements of your cornea today suggested significant flattening off over the last month or so. Yet your vision has been entirely stable. The only problem at the moment is that the left lens has rotated slightly due to it fitting tighter due to your corneal changes, and that has only dropped you to 6/6+.

This is actually not what I would have expected. However, on second thought, I do know that people who have had CXL can wear KeraSoft and see quite well while their corneas are settling.

I am off to give this more thought.....

Lynn