Ophthalmology is a product-centric market so this month Ophthalmology Times Europe decided to ask for a doctor's in depth verdict on one of the latest available technologies for cataract surgery.

WhiteStar Signature is the latest brainchild from AMO phacoemulsification technology. It has been designed to combine and improves the ultrasonic performances and fluidics safety of a product line that began with Prestige and was followed by Sovereign.

The importance of fluidics

Signature was designed to optimize the performances of fluid equilibrium, a key safety aspect in phacoemulsification, by maintaining the volume of the anterior chamber. In technical terms, Fusion Fluidics, the new integrated programme, lowers the vacuum before the occlusion breaks, thus making it possible to optimize the absence of risk of pressure collapse (surge) during phases of phacoemulsification of quarters, even for high vacuum levels. The principle is that of recognition of the occlusion followed by an automatic reaction of the peristaltic pump, to the effect that its direction of rotation reverses as soon as a target value is attained. The vacuum is then reduced within a delay of 20 milliseconds.

Signature is equipped with two aspiration systems: peristaltic and venturi. This double-pump system permits on-the-fly switching between true peristaltic and venturi pumps using one cassette. The pump choice can be preprogrammed by mode or submode. The venturi mode provides additional vacuum and holding power.

Table 1: Settings used in standard ultrasonic mode.

The aspiration capabilities depend on the mode (peristaltic flow up to 60 cc/minl peristaltic maximum vacuum of 650 mm Hg and venturi vacuum up to 600 mmHg). The ability to use both modalities in one system offers flexibility and could be particularly useful in multi-surgeon environments and teaching institutions.

Energy matters

The ultrasound-delivery system is based on Whitestar technology, which distributes 6-ms micropulses separated by 12-ms pauses. In this way, the tip efficacy can be increased for lower energy consumption, thus limiting the risk of temperature elevation (similar to the action of an anti-brake-lock system). These characteristics have been carefully studied as they relate to the risks of heating and corneal burns and the comparative results have been very favorable.

Whitestar Ice adds an initial 1-ms power peak to the micropulse to intensify the cavitation effect (similar to the kick effect during acceleration with an automatic transmission). In this way, the effect is enhanced with only minimal increase of delivered energy. This 'punch' physically separates nuclear material from the phaco tip and permits creation of a 'microvoid' between the occluded tip and the nuclear material. The microvoid allows fresh balanced salt solution (BSS) to flow between the phaco tip and the nuclear material. This fresh BSS interacts with the ultrasonic power to accelerate cavitational emulsification. The efficiency of ultrasonic power is increased.

A new component of the WhiteStar is the Ellips. This is the first phaco technology to simultaneously blend longitudinal and transversal ultrasonic modes in proportions of 50% each. The constant emulsification reduces trapping of nuclear fragments in the tip and thus prevents clogging the aspiration line, even with hard nuclei. It does not necessitate any modification of technique and it functions with any tip style – straight or curved – although a curved tip will amplify the efficacy of the system.

With Ellips, the maximal longitudinal amplitude at the tip is 25 µm at present and it is also 25 µm in transversal mode. In pure longitudinal mode, the maximal amplitude at the tip is 100 µm.

The advantages depend on the phase of surgery, on the tip and on the type of nucleus.

Ergonomics

Improvements have been made to the ergonomics of the machine. For example, a cassette that can be set up with a single 'click' and an intuitive touch screen with an interface that can be programmed in multiple languages. The screen is interactive for easy modification of parameters and it provides access to a text-based mode of use.

Phase changes are validated by acoustic confirmations: a pedal with programmable functions; peripherals (remote controller) with Bluetooth wireless technology and voice confirmation.

The new handpiece can be used in traditional mode or in Ellips, peristaltic or venturi mode.

Surgical Media Center (SMC)

This is a tool for simultaneously recording the video film and real-time information about the parameters used on the hard disk of a portable computer.

The first step consists of separately recording the surgical film and Signature data. The second step permits personalisation of overlaid information. The third step comprises creation of one or more different end-user files for use on different media (DVD, PPT, Web). These files can be transferred via a simple USB adapter.

Verdict

"In conclusion and in practice, Signature permits cataract surgery on nuclei of all grades under optimal safety conditions. As a rule, the technique I use for grade 1 nuclei is one of aspiration and minimal ultrasound, while it is best to use a stop & chop technique for grade 2 or 3 nuclei and a chop technique for hard nuclei.

"Depending on the nature of the implants, I routinely work with incisions of 2.8 or 2.2 mm; more rarely now, although we have done so in the past, we work with bimanual incisions of 1.4 mm and irrigators having a flowrate in excess of 48 cc/min.

"Regardless of the specific techniques, I have always been able to work under optimal conditions, using this technology.

"Furthermore, the Surgical Media Center could represents a potentially ideal teaching tool for analysis and instruction in the steps of phacoemulsification. The use of slow motion is an effective means of viewing and analysing a sequence or a perioperative event, especially in correlation with the machine parameters. The SMC can also act as a high-definition recording tool for subsequent presentations."