 So, I'm Brian Zog, I'm one of the senior residents and today we're going to hear from some of our, a couple of visiting medical students and then a medical student from the University of Utah that's rotating with us. And we're going to start with Kim Lavin and she comes to us from Creighton and she's been on the retina rotation as you can see recently. And she's going to talk about the advantages and disadvantages of a small gauge bit rectomy. Thank you. Alright, well first off I'd like to say thank you to everyone for being here and a special thank you to Dr. Teske for helping me with this presentation and Dr. Mifflin for kind of helping me get the idea for it initially. So, to begin, I like to start with really simple things, what does the word rectomy mean? So if we're broken down into two different words, vrit and actomy, vrit standing for vitreous humor and actomy the new Latin word for ectomia and we speak English so we have to reverse everything. So vritrectomy actually means excision of the vitreous humor. So just some anatomy, the vitreous humor resides in the vitreous chamber, it's composed primarily of hyaluronic acid, some collagen fibers and the dilute saline solution. The only thing I want to point out is the paris plana. This is the area where we actually insert our instruments during vritrectomy and the reason we insert it there is because it's kind of posterior to the ciliary body and anterior to the retina so we won't do much damage. So, start with some history. The first person to kind of describe the procedure of ectomy was Mackamer and he described a 17 gauge cannula that he inserted through a two millimeter sclerotomy site, just one port. A few years later, O'Malley came along and kind of advanced and made this procedure a little better. He introduced the three cannula systems. You actually have three different cannulas, one that you use for infusion and two that you use for instrumentation. And then he also had a smaller gauge. And this is actually kind of the standard vritrectomy that I'm going to be talking about today. Chen came along and tried to introduce this suturalist approach, but it didn't really catch on until 2002 when Fuji introduced the 25 gauge, a smaller cannula that truly was transconcentival suturalist. People still weren't completely happy though and they decided to make a best of both worlds type cannula, the 23 gauge which is in between the size of the 20 and 25, but is still suturalist. And then finally, the most recent advancement in this field has been the 27 gauge. And that's, I nicknamed it the super small gauge vritrectomy. Today though, what I'm going to be focusing on is the 23 gauge and the 25 gauge. And when I refer to small gauge vritrectomy, that's what I'm referring to. And I'm comparing it to the 20 gauge vritrectomy, which has been the standard of vritrectomies for a while. At the very end, I'll give a quick little tidbit about the 27 gauge. So, for completeness sake, I just wanted to include a slide for the indications of vritrectomy, which are many between vitreous hemorrhage to retinal detachment. So, what are the procedures that are different between the 20 gauge and the small gauge? For a 20 gauge, you actually have to make a congenital incision, followed by a sclera incision, insert your cannula, do the vritrectomy after suturing the cannula to the sclera. And then when you're done, you actually have to remove the cannula's suture, the sclera, and then suture the conjunctiva, which makes a airtight seal, but requires a lot of time. And instead of talking about the small gauge vritrectomy, I'm just going to show you a video of how it's slightly different. Wait, there we go. So, to begin the procedure, to insert the cannulas, you insert three millimeters from the limbus, displace the conjunctiva, and then insert the trocar, trocar-guided cannula at an oblique angle through the conjunctiva, through the sclera, and then into the vitreous humor. Once your ports are placed, you'll be able to remove and insert your instruments as needed. And here I'm just showing endo-elimination and cutter being inserted. And then up next, I'm going to show you a picture of what it looks like to look through the wide-angle microscope or lens that we use, just the back of the eye. And then when the procedure is over, you simply remove the cannulas, re-displace the conjunctiva, and you're done. Simple as that, no suture is required. So, what are some of the advantages and disadvantages of using a small gauge vritrectomy? This slide is just a general overview. As far as advantages, it's been proven that there's improved patient comfort afterwards. Having sutures in your eyes is uncomfortable because it's a highly innervated area of our body, so not having sutures is beneficial to the patient. Also, the wounds are self-sealing, and because the actual cannules are smaller, there's less scarring on the conjunctiva. And finally, there's a decreased intraocular inflammation. They believe this is due to the decreased manipulation of the tissue. Some of the disadvantages, the main one I saw in kind of just the literature throughout, was there's a higher incidence of hypotony, and what that means is that postoperative intraocular pressure of less than five or seven, depending on which paper you're reading. And so, the only caveat to this is that they found that after several days, the hypotony completely disappears, and if it is due to a wound leak, is the reason for having the low intraocular pressure. On post-up day one, if you put a suture in, it solves it. Some of the other disadvantages I saw were just related to the instruments themselves. Because they're smaller, they're more flexible. Also, because you're inserting the instruments at an oblique angle, there's an intraocular pressure spike. They measured in rabbits that got up to 63 millimeters of mercury, so quite high. And then also, during the surgery, sometimes the cannulas can fall out. And then, the last kind of thing relating to the instrument, just design, is in order to make them rigid enough, some of the shafts are a little shorter. So if you have a truly myopic eye, it may be a little bit difficult to get to the back, the posterior pull. So just going through some of the topics, as far as advantage and disadvantages. The big one I want to talk about is the laminar flow. So flow, or the amount of suction, you're going to be able to have as related to the change in pressure times the radius of the force divided by length. So with a smaller cannula, you're going to have less power with using your tools. Now, there's two options you can have. But this is one, you can either just be OK with having a slower vitreous removal, or two, you can actually increase the pressure within the eye with a higher infusion aspiration rates, but you have to remember you're also going to be increasing the interocular pressure, so you have to balance how much you want to actually increase that pressure. The only advantage I saw in one paper, they mentioned that some surgeons like the low flow, because you can nibble kind of at the vitreous without worrying about the vitreous being sucked into your instrument. Another important topic is operative time. So in one paper I read, they said that the overall operative time is shorter with the small-gauge vitrectomy. Now the caveat to that is it's shorter because you don't do the sutures, but it will take longer when you're actually performing the vitrectomy. But overall, I think it's an advantage because shorter operative time is better. Also relating to that is cost. So disadvantage is the actual cost of each individual pack is more expensive for the small gauge vitrectomy. But since you have shorter OR time, labor is roughly 70% of the cost of the procedure. So it may overall win as far as reducing the cost for our patients. As far as the pediatric population, the only reason I said that this was an advantage, even though you can seem to think it would be more of a disadvantage, is sometimes the 20 gauge cannulas are just too large with the little eyes. So your only option are a 23 or 25 gauge vitrectomy. And with using the, this is the one little point I want to mention as kids, since there's no sutures, you're going to tell them don't rub their eyes, but a little baby isn't going to listen to you because they don't know what you're saying. So you're increasing the likelihood of wound distortion or they could cause an infection or they could actually cause the wound to leak by messing with their eyes as well. And then the last thing I want to talk about is best corrected visual acuity. So as far as advantage of this, they found in the papers that patients best corrected visual acuity was better at roughly one week to one month compared to the 20 gauge vitrectomy. The only caveat to this is that at six months to 12 months, the best corrected visual acuity is the same. They just, I still think it's better though because if you get your vision better faster, that would be ideal to me at least. And then there's no statistical difference between the two procedures as far as retinal tears or progression of cataracts. Those are complications of a vitrectomy, not necessarily small gauge or 20 gauge. And then the last thing I want to mention is acute postoperative endophthalmitis. Two studies showed that there was increase in endophthalmitis in 2007, 2008, but since that time there's been four studies and there's shown no statistical difference between the two procedures. So in my opinion, small gauge vitrectomy is the superior modality for performing a vitrectomy. And that's primarily because the OR time is less. There's faster visual recovery. There's improved patient comfort and less post op inflammation. And like I mentioned, real quick, 27 gauge is the new kind of instrument tool out there. The reason they decided to test it out was that we've been using 27 gauge needles for many years to do fluid, fluid exchanges, post vitrectomy. So Oshima actually decided to do a study on this. They came up with an instrument pack. They did 31 eyes with various pathologies. And they ended up finding that similar to the 25 gauge, the fluid dynamics and the cutting efficiency was less, even more than the 25 gauge, but 100% of their wounds self-sealed and they were able to actually insert perpendicularly. And there was no hypotony from post op day one. So it kind of solved that one major disadvantage I talked about earlier with the 23 and 25 gauge instruments. So here's my references. And are there any questions? I actually didn't. No, I didn't actually, I didn't actually find, all I found was literature reviews that were just people commenting on their experience as to why they would use a 20 gauge versus 25 gauge. From various institutions throughout the world. And some of them still attest those 20 gauges the best and some still say the 25 is. Dr. Fettie? So my question is, did you come across anything about the gauge? So, sorry, that's the back. So I didn't find anything specific with relation to end ophthalmitis. It varied from anywhere from like 5% to like 25% in the papers I was reading as far as how often it was occurring based on the institution it was done at. They never really specified like exactly if there was a wound like what was the incidence of the, or at least I hadn't come across it in the literature for that specific scenario. I think as we've learned to bevel our entrance site and stuff, those links are really common now. And usually the ones that are gonna leak are very obvious. And usually you have to cut down the content.