September 2009 Advertorial Return to Homepage

Flow Control with the Constellation

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The design of the new CONSTELLATION Vision System (Alcon Laboratories, Inc., Fort Worth, TX) expands on the ACCURUS Surgical Systems (Alcon Laboratories, Inc.) integration theme. The CONSTELLATION system builds on the ACCURUS platform and has improved cutting, better fluidics, an advanced illumination system, and enhanced tool performance. Additional significant improvements on the CONSTELLATION system include new component technologies, an integrated laser system (PUREPOINT, Alcon Laboratories, Inc.), and efficiency components (V-LOCITY, Alcon Laboratories, Inc.).

The aspiration control system not only provides control of vacuum, cutting, and variable duty cycle, but also has flowsensing capabilities. Thus, the surgeon can operate in a true flow mode or flow limiting mode. There is a distinct difference when you can push the foot pedal down and know that flow can be controlled to an exact level through the port. Flow control utilizes a digital feedback loop and an actual flow sensor.

Flow Limiting
Peristaltic pumps produce pulsatile vacuum and work without a feedback loop or flow sensing capabilities. They produce slower vacuum rise times as well as footpedal-commanded flow and/or vacuum decrease. The CONSTELLATION system utilizes a peristaltic pump and allows for 3-D cutting and proportional vacuum control. Additionally, the CONSTELLATION can utilize both flow limiting mechanisms and true flow control.

In addition to flow control the 5000 cpm high-speed cutting rate of the ULTRAVIT probe (Alcon Laboratories, Inc.) coupled with variable duty cycle control produces port-based flow limiting, which I have presented numerous times as a vehicle to decrease pulsatile vitreoretinal traction on both detached and attached retina.

Steve Charles, MD, is the founder of the Charles Retina Institute in Memphis, and is a member of the Retina Today Editorial Board. He is a paid consultant for Alcon Laboratories, Inc. Dr. Charles can be reached at +1 901 767 4499; or via e-mail:

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