Timothy G. Murray, MD, MBA (00:16):
Welcome. I'm Dr. Tim Murray coming to you from Snowmass Mountain for the Aspen Retinal Detachment Society's 54th annual meeting. It's my pleasure to introduce Dr. David Chow, who spoke with us on surgical tips and techniques. Dr. Chow, let me ask you what you think some of the clinical pearls were to take home from today's presentation.

David R. Chow, MD (00:39):
Thanks, Tim. So I tried to share with the audience the highlights of a course I've done for a bunch of years now on like an advanced Constellation users course. And I've given the course around the world and what's happened as a result is I figured out what not beginning surgeons, but expert surgeons don't know about the technology they're using and how I can educate to them to help them be safer surgeons. And so the first tip I shared with the audience was the importance of patient eye level on your aspiration and your IOP. And as I've asked around the world, most surgeons never even look at patient eye level as an issue as they set up for surgery. And the impact of that is, for example, if your patient is 10 inches below the connectors on the constellation, you're creating about 19 millimeters of mercury effect that you have to overcome as you hit your foot pedal on vacuum.

(01:39):
And that would explain why surgeons will sometimes say, I go in the eyes, start pressing the foot pedal and I get regurgitation. Why is stuff coming out of my cutter port? So that helps them understand, oh, look at where your eyes are relative to the connectors. The second effect is on your IOP. And so again, if you're 10 inches below, you're adding 19 millimeters of mercury to the IOP you thought you were operating on. So if you'd set it at 25, you're actually operating at what, 43. That could explain some of the clinical consequences you see during that case. So that was tip one was to go onto that. Tip two was on IOP compensation, a very innovative, creative thing that was added to the Constellation, but there was a lot of confusion as it came out. There were some issues that came out and they still exist to this date.

(02:26):
A lot of surgeons around the world are uncomfortable with it even to this point. And I shared with them a complication that had occurred when a surgeon had gone from an air-filled eye back to fluid and the infusion had kicked on and it created a jet of fluid as IOP compensation tried to catch up and it induced a retinal break and a subsequent retinal detachment. And what most surgeons around the world don't recognize is that a number of years ago, there was a piece of technology added to the software such that when you go from air back to fluid, you can delay the onset of when IOP compensation kicks in. And so what the message is, is make sure you go home. And if you are someone who likes to go from air back to fluid for whatever it is, get out residual oil bubbles, eye dye staining, whatever your reasons or logics are, please set that IOP delay to 15 seconds, 30 seconds, because by doing so, you allow fluid to drip in the eye, form meniscus up so that by the time IOP compensation kicks in, you will not have a jet of fluid go across the eye and create a retinal break or tear.

(03:41):
And I guess the third point I would share is a pet peeve of mine, which is related to surgeons using shave mode with their vitrectomy cutters. And so our modern generation of cutters were dual pneumatic probes - burst of air to close it, burst of air to open it. And as a result, the engineers were able to customize the timing of that burst and customize the duty cycle. So they gave us an option of shave mode, fifty/fifty mode or core mode, which basically meant the proportion of the time the cutter was open. And what kind of drives me nuts is all around the world, surgeons will still talk about using shave mode all the time, but when you ask them, "Do you use your cutter at its full cutting potential?" They'll say, "Yeah". "Do you ever lower your cut rate?" They say, "No." And the problem with that is when you look at the data for all high speed cutters, 10K, 20K, 30K, the lines on the duty cycle all converge.

(04:40):
And so essentially it's a myth or a fallacy that using shave mode, if you use your cutter at its full cutting potential, is doing anything. The only little pearl you could add to that is if you are someone who likes to use your cutter to remove retained lens fragments and you lower your cut rate down to 600 or 800 cuts per minute to get lens material out, the curves do separate. And now you could say, "Okay, I'm going to use core mode so I can engage the lens material and pull it into my cutter at a lower cut rate so I can deform it and cut it and remove it. " So those would be my three pearls that I tried to educate the audience with.

Timothy G. Murray, MD, MBA (05:19):
It was a great talk in its entirety, but that was a wonderful summary. So David, thank you very much for joining us here at Aspen Rental Detachment.

David R. Chow, MD (05:28):
Thank you, Tim, for inviting me.