The design of the Infiniti System (Alcon Laboratories, Inc., Fort Worth, TX) was based on extensive studies of phacoemulsification, including IOP and anterior chamber depth, fluid flow during lens removal, and other variables. This new instrument incorporates several major advances in lens removal technology.
FLUIDICSThe Fluid Management System
The ability of an instrument to alter the flow and vauum parameters within milliseconds is crucial to lens removal, more so than most of us realize. Without excellent fluidics, extracting a cataract is analogous to having a superb automobile that lacks tires; there is excellent potential but an inability to execute the job. Ideal phacoemulsification requires the correct amount of flow and vacuum at each moment, and those parameters must change continuously throughout the procedure. The Infiniti's Fluid Management System samples the vacuum precisely and responds to both directional and quantitative changes in pressure by altering the flow rate. The system can drop the flow rate from 100 cc/min to zero in several milliseconds (Figure 1). When no nuclear material is on the phaco tip, having a great deal of flow and vacuum is counterproductive, and excessive turbulence is created for no purpose. By hitting the brakes or the accelerator, so to speak, in accordance with the surgeon's needs, the unique fluidics of the Infiniti increase the safety of the phacoemulsification procedure and also dramatically improve surgical efficiency.
Impact of Vacuum
The ability to apply vacuum force to the lens greatly reduces the need to apply mechanical forces in order to remove the lens. The fluidics of previous systems have limited our ability to apply vacuum; I am referring to the ability of a given system to maintain pressure within the eye immediately after vacuum force has successfully removed the lens. The Infiniti has fluidic abilities never before witnessed by our profession. With this technology and the 1.1-mm Flared Tip, I routinely use 600 to 700 mm Hg of vacuum (Figure 2) to remove nuclei, and I normally require no ultrasonic energy to extract cataracts of up to grade 2. On other machines, with higher compliance tubing and cassettes, those parameters would collapse the anterior chamber upon successful aspiration of the lens material. Avoiding this complication requires a machine that can (1) nearly or completely eliminate incisional leakage and (2) instantly shut off the pump and prevent the aspiration system from continuing to create a vacuum. In other words, there should be the least possible compliance or elasticity in the aspiration system. The Infiniti meets all these criteria.
Ultrasound
The Infiniti possesses a tri-modal energy delivery platform. The surgeon may select any of the three different means available for removing the lens. The first method is ultrasonic, and the Infiniti has the same ultrasonic power as the Advantec Legacy (Alcon Laboratories, Inc.). I have used the latter technology on a weekly basis to remove red or black nuclei with ultrasonic times of approximately 1.5 minutes and an average power of approximately 40%. I do not believe that any other instrument can remove these types of nuclei more efficiently. This system not only provides a stroke length that is sufficient to remove a nucleus of any density, but it will consistently maintain the stroke length regardless of the load at the tip.
The Infiniti also permits the surgeon to apply microbursts of energy as short as 5 milliseconds or as long as 500 milliseconds. These applications may be performed as infrequently as once per 2.5 seconds, as often as 100 times per second (5-millisecond bursts and a 50% duty cycle), or anything in between. The ability to apply microbursts is not new, but the shortest available bursts on the Legacy were 30 milliseconds.
NeoSoniX
The unique sonic oscillatory energy of this technology will benefit many surgeons. Some will find that, during sculpting, NeoSoniX widens the trough more quickly. When removing nuclear segments of certain densities, other surgeons using NeoSoniX will notice that the fragments remain on the phaco tip, reorient themselves, and are removed more readily than they would be if impaled, particularly if high vacuum is prohibited by intraocular conditions or the surgeon's preference. Oscillation automatically breaks occlusion and thereby causes the nucleus to ?dance? on the phaco tip, thereby changing its orientation. This is particularly valuable for surgeons who use a one-handed technique and therefore do not have a second instrument within the eye.
AquaLase Liquefaction Device
AquaLase propels short bursts of warmed balanced salt solution against lens material. This action appears to have no effect elsewhere in the eye. For example, there is no radiating ultrasonic pressure wave. With the exception of high vacuum, AquaLase may prove to be the gentlest manner in which to remove lens material. Currently, the device removes nuclear cataracts of up to grade 2+ with reasonable efficiency. Because it is exceedingly difficult to rupture the posterior capsule while using AquaLase, the technology may also have applications in polishing the capsule, removing lens equatorial cells, and resident training. AquaLase technology is still evolving. It is certain to offer wider applications within a few years.
Ultrasonic handpiece
Physicians interface with lens-removal instruments through their hands and feet. The handpiece must be comfortable, but most are too heavy. The ultrasonic handpiece of the Advantec Legacy and other machines weigh approximately 98 g, but that of the Infiniti is approximately 41 g and is therefore easy to maneuver. Surgeons need not hold the handpiece in a death grip in order to retain control. As a result, they receive more tactile feedback and are able to execute more precise movements.
Improved Footswitch
The footswitch has been designed so that the surgeon may easily move it on the floor, rather than rely on a nurse to reposition the pedal. In addition, the footswitch can be adjusted to accommodate small, as well as large, feet with regard to length and width.
SETUP TIME
Whereas the Legacy's setup time requires nearly 2 minutes, the Infiniti completes priming and tuning in approximately 50 seconds. I find its prompts and icons to be foolproof. On a busy day, all these attributes are especially valuable.
RISE TIME
Some surgeons favor the classic peristaltic system, which slowly raises the flow rate and vacuum in response to pedal depression and/or tip occlusion. Others are accustomed to the “live vacuum” of a venturi system, which typically has a lag time on the order of 120 milliseconds between pedal movement and machine response. The Infiniti has an adjustable rise time of seven settings that span these response times. In fact, this system can function with a rise time that is faster than that which is available on any other machine including the Accurus (Alcon Laboratories, Inc.). Surgeons should set the rise time to correspond with their own comfort zone, and they may adjust it thereafter as they wish.
CONCLUSION
Justifiably, ophthalmic surgeons often approach new technologies with the fear that, if used improperly, a serious surgical complication will result. This is not the case with NeoSoniX or AquaLase. The learning curve is neither steep nor dangerous, unlike that involved in learning how to perform phacoemulsification.
Surgeons have been phacoemulsifying nuclei for the past 35 years, and I would argue that we have refined the procedure more in the past 2 to 3 years than in all the previous years combined. It is impossible to know what the latest technologies will enable us to accomplish in the future, but we can expect ever-increasing levels of safety and efficiency to evolve.
