A patient with a pterygium that induced three diopters of corneal astigmatism presented for surgery. This was the first case Ashley Brissette, MD, performed with the NGENUITY System (Alcon) which was particularly helpful in keeping everything in focus. Dr. Brissette prefers amniotic membrane in pterygia cases to prevent reoccurrence and preserve the conjunctiva for future procedures.
Alcon Ngenuity • Amniotic membrane graft • Cornea • Pterygium
Hi, I'm Dr. Ashley Brissette from Weill Cornell Medicine in New York City. And I'm presenting a case of a progressive pterygium, that I presented at ASCRS 2019. So, this patient came to see me with visual disturbance. He had over three diopters of corneal astigmatism induced by this progressive pterygium. And, also cosmetically, it was bothersome to him. This was the first case that I had ever done with the NGenuity System (Alcon). The 3-D projection was really great for this case because everything was in focus, so all the way from the central part of the cornea to the very periphery in the screen was completely in focus during the entire case, which really speaks to the visualization of the system. So the first thing that I did here was to avulse the head of the pterygium from the cornea. So I just use a .12 forceps to grab it and you'll see that it peels really easily off of the cornea.
After marking the extent of the pterygium, I excised the lesion. It's really important to always send these lesions for pathology to make sure that there's nothing abnormal within the sample. I then, pull up on the Tenon's and excise. This is a really important step in terms of preventing recurrence from pterygia, to make sure that you're not only excising the conjunctiva, but also that Tenon's. And then you'll see that the conjunctiva actually lays very flat down over this area. The next thing I do is, just using a blade here, is to remove the epithelium from the surface of the cornea. And I also like to go over it with a burr as well. Again, this can help prevent recurrence and just also helps with re-epithelialization over the cornea, so that it can heal quite nicely for these patients.
You might have a little bit of bleeding, and it's okay to do some light cautery, in these cases, as well. I don't need to be too aggressive, because actually a little blood might help with the graft in terms of it sticking down. I then use Mitomycin C soaked sponges, and I just apply them underneath the area of the conjunctiva, just for about 20 seconds, and then irrigate very well with balanced salt solution. The next thing I do is just measure out the extent of my defects. For these cases I like to use amniotic membrane. The reason being is that it actually shows really low rates of recurrence across studies, so only about 0.3 to 3% of a rate of recurrence by using amniotic membrane.
The other thing that's really nice about it is that it preserves the conjunctiva for future procedures. So I've kind of come away from doing conjunctival autographs, and more using this amniotic membrane. So I lay it down, and you can see that there's a little bit of excess, so I'm just trimming the excess. It's really important to make sure that you're having the edge of the amniotic membrane abutting the limbus. So once I've measured it out to the appropriate size, I then lift it up and reflect it back onto the cornea.
I use Tisseel glue here, applying the component to the bed and then also to the graft. And then I actually use two non-tooth forceps to just gently replace the graft over the area of the defect. Once I've put the graft down, I make sure to smooth it out completely over the area of the stromal bed and then tuck the edges of the amniotic membrane. With that tuck technique it is really important to have the amniotic membrane adjacent to the limbus and also into the area of the semilunar fold and caruncle.
And so you can see here, I'm making sure that it really abuts the limbus and then I'm smoothing it out over the area of the scleral bed. And then what I'm going to do is actually tuck those edges underneath my defect. And again, what's nice about this, as I mentioned, is it really preserves the rest of the integrity of the conjunctiva.
And what you want to do is actually go around and make sure that there's no Tisseel glue strands that are attached to either the drape or to the speculum itself. You can see here I find a little one. So I'm actually just going to use the Vannas scissors to snip it, because the last thing you want to do is remove the speculum when it's attached to your graft and you remove inadvertently everything. I like to use a collagen shield in these patients, just for that corneal defect, and that'll disappear after about the first 24 hours. So again, this is the preoperative photo and then this is one month postoperative. So you can see it has great cosmesis, very low rates of recurrence, and really easy procedure to do. Thank you.