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A retina specialist explains why vitrectomy surgery is safer and more efficient using a new ultra-high-speed vitrectomy cutting probe combined with 27+ gauge instrumentation.
By Cheryl Guttman Krader; Reviewed by Pravin Dugel, MD
Los Angeles-A new ultra-high-speed vitrectomy cutting probe operating at 7,500 cuts per minute (Ultravit High Speed Vitrectomy Probe, Alcon Laboratories) combined with use of 27+ gauge instrumentation enables safer and more efficient vitrectomy surgery, according to Pravin Dugel, MD.
“Cutting at a faster rate creates less traction on the collagen fibrils that in turn reduces the chance of iatrogenic tears and retina incarceration, while use of smaller-gauge instrumentation allows a smaller incision size but more importantly improves precision for greater safety and efficiency,” said Dr. Dugel, managing partner, Retinal Consultants of Arizona, Phoenix, and clinical professor, Department of Ophthalmology, Keck School of Medicine, University of Southern California, Los Angeles.
“The 27+ gauge instrumentation with the ultra-high-speed cutter is an appealing combination, because it allows me to remove fibrous tissue safely and effectively in a complicated traction detachment without the need for multiple instrument exchanges,” Dr. Dugel said.
The benefit of smaller-gauge instrumentation is understood on a concept Dr. Dugel named “the sphere of influence” that relates to area of fluidic collateral damage. As instrument gauge size becomes smaller, so does the sphere of influence, and this decreases the amount of flow needed to attract tissue. Less flow translates into less collateral fluidic damage and therefore greater surgical precision.
Dr. Dugel explained this concept using different size vacuum cleaners to retrieve a certain color candy-coated chocolate from a group of candies. The ability to pick up the single-color candy by itself was improved using a hose with a smaller diameter. (See videos this page)
“If the candy of interest represents fibrous tissue and the other candies represent normal retina, it is clear that using a vitrectomy instrument with a larger gauge that has a larger sphere of influence causes more collateral damage and is associated with increased chance of incarcerating normal retinal tissue,” Dr. Dugel said. “Thus, surgical precision is improved with the use of smaller-gauge instrumentation.”
Dr. Dugel acknowledged that concerns have been raised regarding the stiffness and procedural speed of 27-gauge instrumentation. He noted that the flexibility of the instrumentation increases with decreasing gauge size (i.e., 27 gauge is slightly more flexible than 25 gauge).
“However, the clinically relevant issue is whether there is sufficient stiffness, and for me, with the use of wide-angle viewing and reinforcement of the shaft, the stiffness of the 27+ gauge instrumentation is absolutely adequate for what I need to do,” he said.
In terms of how gauge size affects procedural speed, Dr. Dugel noted that flow rate is lower using smaller-gauge instrumentation.
However, maximizing flow rate is not a goal for improving vitrectomy surgery because it introduces the increased risk of iatrogenic retinal tears and retinal incarceration.
“What we are aiming for is to have an adequate and appropriate amount of flow, and that is achievable using the 27+ gauge instrumentation,” Dr. Dugel said.
“Available studies show that by increasing vacuum when operating with the 27+gauge probe, we can increase the flow rate so that it is the same as with 25-gauge instrumentation and very close to that of 23-gauge instrumentation,” he said.
Pravin Dugel, MD
This article was adapted from Dr. Dugel’s presentation at the 2014 meeting of the American Society of Retina Specialists. Dr. Dugel is a consultant to Alcon Laboratories and Novartis.