Non-wetting Issues, Surface Treatments & Hyper Dk Materials
Hello again and welcome to another Contacts with Conway.
My name is Martin Conway, and in this edition, I continue my conversation with
Pat Caroline from Pacific University. We start the conversation by looking at the
non-wetting issues associated with high Dk gas permeable materials, and then we
move on to the possible use of Tangible Hydra-PEG surface treatment for those materials.
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Martin: Most of these lenses at the
moment – I can’t remember what the SCOPE study was, it’s somewhere
like 64% or 74% - 74% are going onto irregular corneas.
Obviously, a lot of these keratoconics have dry eye issues
along with their main problem which is the keratoconus. How are you dealing with
non-wetting of these materials, and have the materials improved since we first
started looking at them 10 years ago?
Pat: Yeah, I’ve got to admit, when we first started working with higher Dk lens materials,
wetting was a pretty significant issue, and I don’t want to trivialise it.
We still have individual patients with issues, but one of the things we have now that we
we didn’t have then, is the Tangible Hydra-PEG system.
And in certain individuals, it has really been a game changer. It’s been a
life saver for some of these patients. Now, of course, the
question that’s always asked is “How long does it last?”
I think the best way I’ve dealt with that
is the fact that it lasts long enough. And what I mean by long enough –
it’s almost like once a patient has been wearing a
lens 2,3,4,5,6 months, their own personal biofilm gets
covered across that lens. Once that happens, we have oftentimes
improved wetting properties, so I think the Hydra-PEG lasts
long enough that it allows the patient’s own biofilm to
kind of take over. Once that’s in place, our wetting issues are
surprisingly minimal today compared to what they were 5 or 6 years ago.
Martin: What sort of percentage of patients
are you actually applying the Hydra-PEG treatment to?
Pat: I think now, we routinely do it on all of our patients with ocular surface disease
that we’re placing into scleral lenses.
But we don’t use it routinely, just on that population we routinely
do it. On our keratoconics, on our post
corneal transplant patients; it’s kind of a wait and see situation.
Do we have some wetting issues that need to be addressed?
It does seem to be a very individual phenomenon.
Martin: We took a brief break at that point and we now re-join the conversation as we
start to discuss the introduction of a new material from Contamac called Optimum Infinite.
Martin: You know, following our work at Pacific
on the high Dk materials, we went on to develop the
hyper Dk material that we now call Optimum Infinite.
And I just wonder whether you could just share with us
any of your experience with it so far.
Pat: Yeah, we’ve done quite a bit of work with the Infinite material,
in the fact that our primary concern was: were we going to be able to
have reasonable wetting properties and
I’ve got to admit, the Infinite wetted very, very well for our patients.
There was this cohort of individuals that really benefitted from the higher Dk,
and that’s those following penetrating keratoplasty.
Our clinical experience has shown us that
individuals with normal, functioning endothelium,
surface disease patients, keratoconics, and so on,
they seem to do well with any material with a Dk of 100 or greater.
But it’s those individuals with compromised endothelium,
the post penetrating keratoplasty patients
that have always required that extra level of permeability.
And that’s what we get with the Infinite material, we get the added oxygen
permeability, without losing any of the other
performance properties in the scleral lens.
Martin: Good to hear, so you’re using it principally as a problem solver?
Pat: Right now, that is the truth. We are using it primarily as a problem solver,
but as with many of our problem solvers,
they eventually evolve into our primary material of choice.
If the Infinite continues to perform like it does,
I think we’re going to see ourselves evolving in that direction.
Martin: That’s good to hear. I’ll pass it onto the guys that developed it,
they’ll be pleased to hear the feedback. I mean, we did develop it
with the aim of boosting the Dk above and beyond what was available on
the market to date. But also, not to require any
additional surface treatment in the lab. And the other thing we built into it,
we hoped, was the fact that it
withstood handling better. Some of these hyper Dk
materials have been very prone to scratching.
The feedback we’ve had is that
it stands up to patients handling over the period, and also within the lab.
Obviously with some of its predecessors, materials of this range of hyper Dk levels
– it was very difficult to get them through the lab even, in one piece. They required that extra
special handling. And this we hear doesn’t appear to
to have that issue. But thanks very much for your feedback on that,
I’ll certainly pass it onto the guys in the lab.
Pat: Thank you
Thank you for watching
Martin: Well thank you very much for your attention once more.
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