The Evolution of Vitrectomy Technology: Do We Really Need Another Machine?
KIRK H. PACKO, MD
Since Robert Machemer introduced the VISC as the first commercial vitrectomy system in 1972, the technology for safe vitreous removal has changed substantially. The original VISC cut at speeds of 60 cpm, used a probe requiring a 2.5 mm incision, provided very crude fluidics, and often caused as much ocular damage as ocular therapy. Still, it was a landmark instrument that launched a specialty of extraordinary abilities in combating blinding diseases.
Our probes have become smaller and smaller. Cut speeds have gotten faster and faster. Fluidics control has become exquisitely responsive. Complication rates have fallen, and visual results have climbed. Current vitrectomy consoles are now marvelously integrated machines achieving safe tissue removal in ways retinal surgeons only dreamed of 35 years ago. It staggers the mind to reflect on how air travel has evolved since Kitty Hawk's historic flight just over 100 years ago. The three decades of vitrectomy machine evolution has the same evolutionary slope.
Urban legend records a quote from Charles Duell, the U.S. Commissioner of Patents, in 1899: "Everything that can be invented has been invented." Yet, a few important inventions did take place after 1899. Although the statement was probably fiction, it does point out that consumers often assess new technology as the end-all for our needs. Our imagination often cannot keep up with our abilities. Free enterprise also breeds "me too" products once new technology is invented. When one manufacturer hits on a useful idea, other companies are quick to make small tweaks and then market them as new concepts.
While evolution should be based on "survival of the fittest," technology evolution is often driven by "survival of the best marketing department." Cloth towels were followed by paper towels with "Quicker Picker Upper" abilities. Enter now the era of "ShamWow" with enough absorbency to drain Lake Michigan with a single swipe. Hoping to cash in on the craze, there are now ShamWow me-toos. ShamWow claims 20 times the absorbency of paper towels — Zorbeez claims 27 times the absorbency. Does this remind you of a vitrectomy cutter that can cut at 1500 cpm and another that cuts at 2500 cpm? Let's get real here. What is really new vitrectomy technology and what is a "Zorbeez"?
In the fall of 2008, Alcon Surgical launched the new CONSTELLATION® Vision System, boasting the marketing tag line, "One Giant Leap for Vitreous Surgery" with Neil Armstrong-esque fanfare. Current systems such the Alcon ACCURUS® and the Bausch & Lomb MILLENNIUM® have become reliable workhorses with spectacular fluidics and surgeon control. Are we seeing a true evolution in our technology, or is this new machine merely souped-up bells and whistles with unnecessarily higher cutting rates, and even more unnecessarily higher price tags?
The Alcon CONSTELLATION® Vision System does indeed bring to the surgical suite new technology, and is not merely a new box full of prettier replacement technologies. The biggest paradigm change is the ability to control duty cycle as a means of flow control. The past 30 years of probe evolution has demonstrated the value of high-speed cutting as a means of decreasing tissue traction and minimizing vitreous turbulence. Retinal tears have become less common, accordingly. But high cutting rates with pneumatic probes have a double-edge sword in that flow rates have fallen off considerably due to the inherent reduction in duty cycle with high blade closure rates.
The CONSTELLATION® Vision System technology offers the ability to choose either open priority or closed priority duty cycles regardless of the cut rate, and this is indeed a new approach to flow control. Now, the cut rates can be decreased again even to levels allowing the surgeon eyehand reaction times to be operant. With a closed priority cycle, the probe is closed between each cut and flow is absent. Tissue movement is then only apparent for the brief moment that the blade is actually opening and closing. Cutting on the retinal surface can thus be very controlled, and with scales even better than our current systems.
Another exciting new technology never achieved in prior systems is IOP control. By incorporating the infusion into the eye through the machine, the infusion can be constantly modified during fluid removal. The process is dynamic and rapid, allowing the ocular pressure to remain more stable during the procedure. This should possibly allow a lower initial setting of the ocular pressure, providing safer perfusion to the retina. The avoidance of huge pressure swings during instrument exchanges and other maneuvers may cut down on intraocular hemorrhages, corneal and pupil problems, and ultimately provides potentially better visual outcomes. This technology opens a new parameter to be studied, and the specialty will learn just how advantageous this concept actually is over the next few years.
In addition, there are multiple areas of improved technology that are welcomed enhancements to our prior evolutionary developments. These include even higher cutting rates of 5000 cpm, which minimize tissue traction even further while still maintaining adequate flow. The xenon illumination is even brighter, but also more efficient through the use of RFID-recognized probes that automatically regulate maximum levels of luminance. An auto-gas delivery system provides greater sterile delivery technique, while increasing efficiency and minimizing waste. Limitless reflux with proportional control allows the ability to irrigate tissues within the eye with ease.
Finally, there are the "bells and whistles," too. But just because they are more creature comforts for the surgeon, they are still welcomed enhancements to the surgeon and staff alike. Bar code recognition of products, RFID recognition of key consumables, removal of stopcocks to allow auto-infusion changes, rapid push-priming rather than pull-priming the tubings, variable mapping of the foot pedal per surgical mode, an integrated laser with foot pedal control of parameters, and video assist set-up screens are only a few of the enhancements that make the CONSTELLATION® Vision System amazingly user friendly. And while user friendliness alone may be enough, the time savings achieved in an otherwise expensive OR setting may be equally of value.
As new vitrectomy technology was evolving particularly during its heyday in the 1980s, it was common for surgeons to utilize lots of toys and products during a case. Machines were stacked one on top of the other, and individual probes, fibers, and gizmos abounded. Retinal surgeons certainly did their part in fueling the rapidly rising cost of medicine by embracing the use of these new toys. As the world's economy has tightened and the cost of providing medical care has become critical, retinal surgeons in the new millennium are now charged with being more cost conscious.
As new technologies enter our OR, they often enter with hefty price tags. It must be our responsibility to be critical of what the marketing claims offer. Is this truly a new technology? Will it allow me to operate with greater safety and with methods that I can't achieve with my present machine? Or is this a fancy retinal ShamWow? The Alcon CONSTELLATION® Vision System brings us more than just a ShamWow window dressing.
Experts in this special issue of Retinal Physician discuss how this new technology may have value to us, to our hospitals, and to our patients. During the next several years we will learn the nuances of this new technology and how best to use it. In my initial use of the CONSTELLATION® Vision System, it does indeed appear to be worthy of the "One Giant Leap for Vitreous Surgery" tag. The community will now decide for itself. RP
|Kirk H. Packo, MD, is professor and chairman of ophthalmology at Rush Medical College, and assistant professor and chairman of ophthalmology at Illinois Eye and Ear Infirmary, both in Chicago. He has served as a consultant and has received research funding from Alcon Laboratories, Inc., Fort Worth, Texas|