Straight From the Cutter’s Mouth: A Retina Podcast, hosted by Dr. Jay Sridhar, is a wonderful weekly podcast for ophthalmologists, featuring insights from both prominent, as well as up-and-coming retina specialists, about their lives, passions, and work.
In this episode, Dr. Fisher discusses a variety of tips for employing the endoscopic vitrectomy, his favorite gauge to use, and the top scenarios for when endoscopes are more useful than microscopes. For the link to the full episode, click here.
What are your best tips for using the endoscope for endoscopic vitrectomy?
The endoscopy is really helpful at times when you can’t see with a microscope. Most of the time we can see. However, there are moments in time when the microscope is less advantageous.
Here are a few example scenarios related to endoscopic vitrectomy. The cornea suddenly becomes clouded and you can’t clear it. You’re doing an air fluid exchange and you suddenly lose track of where your vision is, because a small bubble gets into the anterior chamber; you have to stop and displace it. Sometimes, you can displace it and then another one comes up. Or you fill the anterior chamber with some products so that you can displace the bubbles away.
Initially, all you needed to do was be able to finish an air fluid exchange and put a little laser in. Now you’re frustrated by the pupil coming down, the bubbles in the anterior chamber; everyone is tired, and everything suddenly becomes much more difficult. During these moments, if you have an endoscope and know how to use it, it can save both you and your patient a great deal of effort, extra surgical time, and extra surgical procedures, to try and re-establish a view.
Tip #1: Start in a laboratory and understand the machine.
I always tell people if they’re going to start to do endoscopy, you should start in a laboratory and understand the machine. Endoscopies have been around since the time of Harvey Thorpe in the 30s, and those endoscopes were enormous, they were like 6mm wide and you had to lean over because there was no flexibility, and people didn’t want to deal with them.
It wasn’t until the 1990s that fused fibers and GRIN endoscopes came out. The GRIN scope was a glass rod and the fused fiber was a pulled series of fibers usually between 10 and 30,000 pixels. They’re all made basically by various companies — some in Japan, some in other places — and then they’re put into instruments that you can easily hold in your hand, and give you both light and vision.
Usually about 10% light goes down the endoscope and about 90% is upviewing. So you can get a fairly good image. It’s not as good as a microscope, but it’s pretty good if you can’t see through the microscope, because now you can see, and before you couldn’t.
The only thing you need to learn with endoscopic vitrectomy is the learning curve. There aren’t many instruments out there — I built one myself with a company from Canada years ago, and we used it for a very long time, and the other one was made in New Jersey, not from me, by another physician, and that’s the one currently available. That comes in either 20 or 23 gauge.
20 gauge is what I’m used to; the 23 gauge came out some years ago, but it’s not as strong and not as capable of torquing. So if you’re going to move it, it more easily breaks. They’ve reinforced it, but if you’re not careful, you’ll break it.
Tip #2: Study our courses on OphthalmicEdge and practice with eye bank eyes.
It has to do with registration. You’re looking at everything on a high-resolution TV, high-definition, and you’re imaging the interior of the eye again with an instrument that you’re not used to. It’s disconcerting in the beginning, so I recommend that if you’re going to start with endoscopy — number one: go look at our courses on OphthalmicEdge, and then arrange to get some eye bank eyes.
It allows you to get a feel for what it’s going to be like in an operating room. It’s really, really hard to just start cold with endoscopic vitrectomy. The time you need is not the time to learn how to use it. The time to learn it is in a laboratory setting with eye bank eyes, if you can. Then progress to using it on clear media cases, recognizing that if you’re using it at 20, which gives you a little better image — not terribly better — and a little bit more view, you’re going to need to enlarge one of your ports.
Tip #3: Gain clarity on how you’re planning to use the endoscopy.
It’s a decision-making process of when you’re going to use it, what you’re using it for, are you going to place it nasally or temporally, and then how you’re going to use it.
Meaning, are you just using it for viewing? Like, to determine whether or not you should even go on with a case?
Are you going to use it with a laser that’s internalized and it’s usually an 8/10 laser inside of it — not my fondest laser, and I don’t like it as much, because it’s infrared and its burn is more difficult to control — I would prefer a frequency doubled green, a 5/32 or something like it, and I usually put it either on a working channel on the scope, or I put it in my other hand, and that’s the second thing that you have to learn, which is how do you arrange to view with one hand, and learn how to manipulate it in a non-stereo fashion on a screen, with your other hand.
How you move around the eye, not to lose the tip of your second working instrument, does require a little bit of knowledge; like learning how to use chopsticks. You can’t move your working hand until you can view where you are with your endoscope. That’s the learning curve. But once you learn it, you get quite comfortable.
Tip #4: Learn how to work on the retina.
The last part of it is learning how to work on the retina. Not laser, which you can apply from a distance, and I usually will light the instruments in my working hand, and I use basically the flashlight effect, because as you approach the surface of the retina, the image of your working hand light gets narrower or smaller — less of a circle — and that means you’re getting closer, and closer, and closer to the surface.
There’s all these monocular clues that you have to learn when you’re doing monocular surgery, and not stereoscopic surgery. But it’s very, very helpful in tense situations when you suddenly lose a microscopic view.
OphthalmicEdge is a free, educational two-portal site with one goal: to provide valuable resources and a better understanding of ophthalmic subjects for both professionals and visually-impaired patients dealing with changes.