Daniil Peshkov/Dreamstime
Fig. 1

Pneumatic Valves Control Cataract Surgical Tool

Dec. 21, 2020
The valves let the new device make fast, accurate cuts and simplify adjustments for doctor preferences.

Cataracts is an age-related condition that creates a growing cloudy area on the lens of the eye and degrade a person’s vision. They are quite common among older people. In fact, The American Eye Institute estimates that half of all Americans 80 or older either have cataracts or have had surgery to remove them. Cataracts can also be caused by eye injuries or other eye problems such as glaucoma.

There is only one treatment for cataracts: surgery. It can eliminate the cataract and correct much of the vision problems they cause. That is why the procedure is one of the most common forms of surgery.

To make cataract surgery even safer and “more routine,” engineers at BYTEC Medizintechnik in Germany developed QUBE and QUBE Pro, two devices that let eye surgeons carry out operations error-free. They also let the doctors adjust the devices to match their requirements and preferences in surgical technique.

During cataract surgery with QUBE, an ultrasound probe breaks up the cloudy lens. The lens fragments are then removed by cutting them into small pieces and using a suction/rinsing device. A closed-loop, proportional MPYE flow valve from Festo quickly responds to the surgeon’s inputs so that flow is tightly controlled. The reliable valve has industry-leading response and flow control needed for this demanding surgical application.

The eye is then infused and cleaned. Infusion pressure needs to be accurately regulated to maintain the structure of the eye during surgery. The fast response of the piezo valves is well-suited for this application. They also do not generate heat, use little power, and are lightweight and small, making it easier to build a compact surgical device. The Festo VEAB proportional precision regulator combines piezo valves with closed loop sensing and electronic control in a small package.

Most other QUBE functions are pneumatically controlled using solenoid valves. They drive the surgical tools, the vacuum-assisted suction, and the delivery or infusion of liquids. Festo provides a broad range of specialized valves to meet each specific application requirement. For example, to get a high cutting rate (up to 7,500 cuts per minute), which lets the surgeon work more precisely and cleanly, BYTEC uses fast-switching MHA2 valves from Festo to get these speeds.

BYTEC also had the design team at Festo develop a compact valve control block for the QUBE pro. It resulted in a manifold duct plate which contains  all the pneumatic connections and protects them in a tubeless supply that uses ducts instead.

The manifold design also includes hollow spaces and silencers that otherwise would have required separate components. This made the control block half the size of a conventional control block with numerous individual tubing connections for each pneumatic component. The manifold duct plate is also equipped with a common electrical interface for all solenoid coils and sensor signals.

About the Author

Stephen Mraz

Steve serves as Senior Editor of Machine Design. He has 23 years of service and has a B.S. Biomedical Engineering from Steve was a Flight officer in the U.S. Navy. He is currently responsible for areas such as aerospace and medical.

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