-: Hi, this is Chris Sales at the University of Iowa.
I'd like to show you a technique
for augmenting the posterior pressure in DMEK surgery when
there is not enough pressure
to shallow the chamber sufficiently.
After removing the Descemet's membrane, I like
to inject a bubble so I can see if there's any
retained fragments.
When I remove the bubble, I can then see if the cornea is
indenting towards the iris
or whether the cornea is remaining a relatively normal
shape, and the iris is coming forward due
to posterior pressure to shallow the chamber.
In this particular case,
the cornea was indenting towards the iris,
so I placed three tips of Weck-Cel sponges
beneath the specula, and that seems like an odd thing to do,
but what it does is push on the sclera,
which then in turn creates more posterior pressure.
And here you can see that the bubble
that's still in the anterior chamber stays at the corneal
apex because there's no dent there anymore,
whereas here, it's off to the side because there is a dent.
Although I don't normally use OCT my surgeries,
it's probably an easier way to see
what I'm talking about.
Here you can tell that if I place posterior sponges
beneath the specula and then shallow the chamber,
it shallows quite a bit more readily than without the
sponges back to our case.
Once the sponges are in place, I deepen the chamber,
do a final cleanup, inject the tissue, open the tissue,
place a bubble,
and then refill the anterior chamber with BSS. At this point,
once we're pressurized again, I remove all three sponges
and it could be two sponges,
it can be one sponge, sometimes four.
I then further fill the anterior chamber with BSS
and do a final bubble titration.
I like this technique because it gets me out of jams when I
wish I was doing a pull-through technique
where I did not have to rely on posterior pressure.
But obviously I can't exchange the
preloaded tissue that I have.
And so in the situations where I realize
that I'm going to need more posterior pressure than I have,
I can augment it with some sponges.