MICS phaco machines: how far have they come?

Key Points

Following the initial insight of Dr Amar Agarwal,¹ microincision cataract surgery (MICS) has been undergoing a steady evolution regarding new technologies, the aim being to optimize the capabilities of this minimally invasive technique. We describe below how new instruments and technologies have now been developed to manage the main problems of fluidics and ultrasound - factors that had particularly plagued those surgeons who practiced bimanual MICS.

WhiteStar Signature System

AMO

The WhiteStar ICE technology has been developed to reduce total ultrasound time by modifying the interval between the ON and OFF phase.

With the new Variable White Star software it is possible to choose, with the pedal, from four different duty cycles, allowing the surgeon to cater specifically for different cataract types. We believe, however, the real benefit of this software can be seen in its ability to create micropulses of 4 millisecond each (hyperpulses), thus reducing ultrasound emission.

The new ICE technology has also been modified to improve ultrasound management: the Pulse Shape program allows the remodelling of the classic ultrasound square wave creating an amplitude extension in the first millisecond ("Kick"). This creates a micro-space between the phaco tip and the cataractous material, through which the BSS penetrates thus increasing the cavitational effect. Consequently, greater ultrasound efficiency and a reduction in the number of mechanical manipulations can be achieved.

Stellaris Vision Enhancement System

Bausch & Lomb

Bausch & Lomb's latest unveiling, the Stellaris Vision Enhancement System, hit the market in September 2007. It's an extremely functional machine with a futuristic design, and presents several advantages over other systems: an easy package assembling system that is assisted by a video on the TouchScreen monitor; the double-linear pedal that is, for the first time, wireless, thus reducing clutter in the surgery room; streaming video making it possible to visualize the surgery on screen. The fluidics are managed by a double-pump system, which is interchangeable during surgery, through EQ fluidics technology. EQ stands for 'equalizing', which means that infusion and aspiration work in mutual equilibrium. The Advanced Flow System is a new generation peristaltic pump that allows very good surge control, thanks to the presence of a hybrid venting system (working with both air or fluids), and to the greater material rigidity of the pipes and transducer.

But the real innovation of this phaco machine is the Advanced Vacuum System. This is an advanced vacuum control system that is based on a centrifugal pump with a venturi valve. This pump is linked to an inner pressure applicator, and offers the same performance as that of a venturi pump (from 0 to 600 mmHg in 1.3 secs), but with the safety of constant fluid aspiration, and the stability of the StableChamber pack, which provides improved holding power from high vacuum settings, and restricted flow, thus preventing loss of chamber stability and reducing post-occlusion surge.

The new Stellaris Custom Control System II allows the surgeon to choose from different modes of ultrasound emission: continuous, pulsed or in bursts (single or multiple). The phaco probe is extremely innovative; it is smaller and lighter, with a practical and ergonomic design. This phaco probe represents a clear evolution in technology, mainly because of the presence of six piezo-electric crystals (instead of four) that work at 28.5 kHz versus 40 kHz of the common probes, thus allowing greater elongation of ultrasound with the generation of less electric energy, greater efficiency and less thermal dispersion. The connections for irrigation and aspiration lines now have a luer lock to prevent disconnection during surgery.