Keeping a clear view

Article of 27 July 2018 


A cataract is an eye condition where the eye lens becomes cloudy and vision is impaired. By means of an eye operation, full eyesight can often be restored these days. Operation systems with pneumatic valve technology help eye surgeons to provide precise and error-free treatment.

A cataract is an eye condition that may be congenital or develop over the course of someone’s life – most often in persons over 60 years old. An operation may well be unpleasant, but is perfectly feasible these days. During the procedure, the clouded eye lens of a patient is fragmented using ultrasound. The operating surgeons then take out the old lens fragments, remove the tissue remnants and finally insert a new, artificial clear lens.

Rinsing eyes with the help of piezo valves

Operation systems help surgeons with the various operation steps. After fragmenting the old lens, the operating surgeons use a special device to completely remove the lens fragments. The device sucks liquid and lens remains from the eye and rinses the eye out at the same time. What is particularly important here is that the pressure used to suck out the liquid and spray it into the eye must be precisely controlled in order not to damage the highly sensitive inside of the patient’s eye.

The precise regulation of the pressure in the operation system is made possible by piezo technology. With piezo valves, a voltage is applied to two plates made of ceramic materials that are bonded to each other, making them bend in a certain direction. With the help of the tiny bonded plate (also called a transducer), the valves can be opened and closed. When electricity is applied to the transducer, the ceramic layer contracts and thus bends the tiny plate upwards – the valve opens. When the power is switched off, it returns to its original shape and then closes the valve. The higher the voltage, the wider the valve opens – in this way, the pressure can be exactly controlled.

How a piezo valve works
How a piezo valve works

Tissue removal helped by quick-acting valves

Besides the suction and rinsing process, the surgeons remove tissue at the back of the eye axis near the retina during the cataract operation. For this, they use a cutter. This is a cutting tool that enables fast and small incisions. The more incisions per minute are possible, the better the doctor can work.

Pneumatic valve technology is also useful for this function. The required cutting rates of up to 7,500 incisions per minute are able to be achieved with the help of quick-acting valves. The valves contain a magnet, into which a relatively high current is introduced for a very short time. This builds up the required magnetic forces very quickly, which attract the valve body and the valve opens. The current is then rapidly turned down to a minimum and finally turned off, causing the valve to close again. Quickly reducing the current makes very high cycle rates possible, in other words a constant opening and closing of the valve, without the magnet overheating and the valve failing. The valve also switches very uniformly during each cycle, meaning that the operating surgeon can make very precise incisions – and the patient soon has full eyesight again.

  • Byetec

    The QUBE pro operation system developed by the company BYTEC Medizintechnik with suction/rinsing device and cutter

  • Byetec

    Pneumatic valve technology integrated in the system: VEAB piezo valve and MHA2 quick-acting valve produced by Festo