Article Date: 2/1/2009

Architecture of a New Vitrectomy System
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Architecture of a New Vitrectomy System

STEVE CHARLES, MD

The CONSTELLATION® Vision System (Alcon Laboratories Inc., Fort Worth, Texas) is the culmination of more than 3 decades of evolutionary development of vitreous cutters and fluidics, new and improved tools, illumination sources, phaco technology, systems integration, efficiency systems, and advanced user interface design.

To appreciate how far we've come, I'll review the key advances along that evolutionary timeline and discuss the refinements and new features that make up the CONSTELLATION® system.

BUILDING ON EARLIER INNOVATIONS

The CONSTELLATION® Vision System incorporates improved designs of all the technologies from the Ocular Connection Machine (OCM) and the ACCURUS® Surgical System, and adds many new capabilities. Some key features include:

Vitreous cutter. This is the pivotal component of any vitreoretinal surgery system. The CONSTELLATION® ULTRAVIT® cutter uses dual pneumatic actuation and operates at 5000 cpm. The cutter is driven using proprietary variable duty cycle technology to control the dual actuation system. Variable duty cycle control enables a "Shave" (port biased closed) setting to produce increased port-based flow limiting when working close to the retina for vitreous shaving. Alternatively, port-based flow limiting can be decreased by using a "Core" (port biased open) approach, enabling greater flow rates during core vitrectomy.

Aspiration system. A dual chamber cassette design and a dual proportional valve aspiration system ensure a low latency response time to foot-pedal commands to decrease or increase vacuum. Sensor-based digital flow control and flow limiting facilitate working safely near the retina. The aspiration system provides linear (proportional) reflux, as well as microreflux for all aspiration tools.

Illumination. The system includes 2 dual-port xenon illumination sources to facilitate use of illuminated tools, chandeliers, and torpedoes. The new xenon illuminator has a proprietary design that produces a consistent light output for 200 hours. The xenon bulb is monitored to provide total lamp hours and colored indicator feedback on lamp life. Green denotes 0 to 200 hours, yellow denotes 201 to 400 hours, and orange denotes 401 to 800 hours. The ENGAUGE® radio frequency identification device (RFID) connectors on the illumination tools automatically adjust the initial xenon source intensity, depending on specific tool characteristics, such as light throughput, typical working distance, and divergence angle. The set-point is 8 to 10 lumens, which is optimal intensity for all 20-, 23-, and 25-gauge tools. When necessary, the surgeon can increase illumination to the maximum output allowed by the FDA.

IOP control. Integrated pressurized infusion and servo control of the intraocular pressure (IOP) is unique to the CONSTELLATION® system and is invaluable in high-flow scenarios, such as pars plana removal of dislocated dense lens fragments using the fragmenter and 23- or 25-gauge infusion. IOP control reduces sudden IOP decreases and resultant bleeding after dense epiretinal membrane deforms through the cutter port. It is likely that IOP control will enable lower average infusion pressures. The infusion system has an automatic "bottle out" warning and enables bottle change with no interruption in fluid flow and no need to reprime the system.

Computer operating system. The CONSTELLATION® system uses a real-time operating system and distributed processor architecture, ensuring reliability and fast response times. The electronics have power backup in case of power failure in the operating room. The console was designed to allow for easy upgradeability as new modules, tools, and software are developed.

Steve Charles, MD, is director of Charles Retina Institute in Memphis, TN. He is clinical professor of ophthalmology at the University of Tennessee and an adjunct professor at Columbia University College of Physicians and Surgeons in New York. Dr. Charles reports significant financial interest in Alcon Laboratories Inc. (consultant).

ADDITIONAL NOTEWORTHY FEATURES

Designed for efficient, safe vitreoretinal surgery, the CONSTELLATION® Vision System also incorporates V-LOCITY® Efficiency Components, designed to optimize OR set-up, enhance the surgical experience and increase OR productivity.

A barcode scanner included with the system allows the staff to quickly scan vitrectomy packs or related consumables at any time during the surgical procedure to track inventory and assist in case set-up.

As previously mentioned, the CONSTELLATION® system employs ENGAUGE® RFID technology in the tool connectors to activate parameter and mode setup, decreasing setup time, as well as work-load and training requirements for the scrub and circulator.

A sterile draped articulated arm with a tubing management system enables priming and testing of all infusion and aspiration components before the patient is anesthetized, prepped, and draped, significantly decreasing setup time. Embedded wizards and video help facilitate faster setup, even when using less experienced personnel.

The CONSTELLATION® system can be configured with an embedded PUREPOINT® 532 nm laser incorporating a thin-disk laser engine, which is the newest, most reliable diode-pumped source available. A separate foot pedal controls laser power and standby/ready with voice verification, eliminating dependence on the circulator. An auto-infusion valve replaces the stopcock for fluidair exchange, allowing rapid transitions between fluid and air. This valve can be controlled by the surgeon's foot or the scrub tech, using the CONSTELLATION® system's graphical user interface.

An auto gas fill system enables filling a syringe with undiluted gas from attached tanks of SF6 and C3F8. This reduces gas waste, ensures sterility, and eliminates the need for the circulator to assist the scrub tech. A software-based calculation applet helps determine how much air to add to the gas to produce the desired concentration. The final step in mixing the gas is done manually, according to conventional practices.

The CONSTELLATION® system has proportional control of a new, higher-frequency diathermy system to produce a more focused lesion, possibly reducing retinal damage.

Power forceps with linear (proportional) control and power scissors with single-cut and multi-cut modes support disposable ALCON® GRIESHABER® DSP forceps and scissors tips. Bimanual surgery is supported by single-pedal linear control of power forceps to grasp and stabilize the epiretinal membrane during the initial segment of pedal travel, followed by control of the power scissors or vitrectomy probe with further depression of the pedal.

Surgical parameters, laser log and consumable use data are generated automatically for analysis or incorporation into an operative note, which can be transmitted to a wireless printer for patient record inclusion, inventory control, cost accounting, and billing.

ROBUST PLATFORM

The CONSTELLATION® Vision System heralds a new era in vitreoretinal surgery. Advanced technologies support innumerable surgical tasks, approaches and procedures. The system will enable experienced surgeons to efficiently perform technically challenging and potentially new procedures. What's more, in my opinion, the CONSTELLATION® system is easier to set up and operate than any other vitreoretinal system, facilitating use by less experienced surgeons. The incorporation of many technologies designed to increase efficiency and decrease turnover time will reduce labor costs and save OR and surgeon time. RP



Retinal Physician, Volume: , Issue: February 2009, page(s):