5.3 MICS with Different Platforms

Phacoemulsification Machines. AJO 145:1014–1017 [14]

Figure 1

19.Wade M, Isom R, Georgescu D, Olson RJ. (2007) The impact of Cruise Control on Millennium with the venturi pump is clearly evident. 33: 1071–1075 [13] Figure 3

20.Georgescu D, Kuo AF, Kinard KI, et al (2008) A fluidics comparison of Alcon Infiniti, Bausch & Lomb Stellaris, and Advanced Medical Optics Signature phacoemulsification machines. Am J Ophthalmology 145:1014–1017

21.Mackool RJ, Sirota MA (2005) Thermal comparison of the AdvanTec Legacy, Sovereign WhiteStar, and Millenium phacoemulsification systems. J Cataract Refract Surg 31:812–817

5.3 MICS with Different Platforms

5.3.1MICS with the Accurus Surgical System

Arturo Pèrez-Arteaga

Core Messages

ßWhile performing MICS with the Accurus machine, the fluidics are improved, because of

the advantages of fluidics control for posterior segment surgery in addition to those for anterior segment surgery.

ßThe use of internal forced infusion incorporated in the Accurus machine is a very efficient

tool, especially when using incision sizes of less than 1 mm.

ßThe internal forced infusion has the advantage of maintaining a constant positive intraocular

pressure, thereby avoiding the surge

ßThe key to using forced infusion is to obtain a fluid rate of 45 ml/min as a minimum, with the

irrigating chopper or cannula that the surgeon is accustomed to use. There is no single parameter for all devices. Settings must be individualized.

ßThe force of infusion can be preprogrammed and so the surgeon is able to switch between

two different forces with only the foot-pedal, avoiding the need for touching the panel or the remote control.

mainly for posterior segment surgery (vitreo-retinal procedures), but also the necessary characteristics to perform anterior segment procedures (cataract surgery and anterior vitrectomy). So when it was released in the surgical market for the first time, it was mainly used for the posterior segment surgery, and the features for cataract surgery were secondary, utilized as an accessory or auxiliary device.

When MICS was conceived for the first time by authors like Professor Jorge Aliò and Prof. Amar Agarwal, one trouble to solve was the amount of fluid incoming the eye during the phacoemulsification procedure, because the irrigating chopper has less irrigation rate than the irrigation sleeve (it has small diameter) [1–6]. So for the first time, some systems were adopted, like elevation of the bottle, use of a wider irrigation line, or even a double-bottle system, with the objective to increase the fluid incoming inside the eye and avoid surge. At that time Sunita Agarwal, from India [7], described the use of an external air pump to “push” the air inside the eye in an active way, avoiding in this way, the use of passive methods (that utilize the gravity force) to increase the incoming fluid; this method was called external forced infusion [8]. Nevertheless, to incorporate an external air pump was not an easy approach, because it must be calibrated in an “empirical” way, according to the diameter of the instrumentation and the amount of vacuum utilized, until the exact amount of fluid to avoid surge was obtained; furthermore, most of the air pumps utilized to create external forced infusion were not created initially for ophthalmic purposes, creating this way less confidence among the ophthalmic surgeons. At that time, we realized that the Accurus machine contained an air pump inside (conceived for posterior segment surgery, but with the possibility to be incorporated to the anterior segment procedures); so we started to work with the objective to obtain the ideal pressure according to the instrumentation utilized to perform MICS. It worked, and it worked really nice. The use of an air pump that is inside the phaco machine to actively push the fluid inside the eye and avoid in this way the surge in MICS procedures was called internal forced infusion (Fig. 5.15) [8–12].

The main advantages of internal forced infusion are as follows:

1.It actively pushes fluid inside the air by creating an active air cushion inside the bottle (Fig. 5.16).

Fig. 5.15 Air Pump in the Accurus Surgical System. It is used in MICS to create Internal Forced Infusion

Fig. 5.16 Internal Forced Infusion active through an Alio’s Irrigating Chopper

2.It can be digitally controlled at the same panel that contains the phacoemulsification settings (Fig. 5.24).

3.The parameters can be modified during the procedure according to the particular needs of the case (Figs. 5.21, 5.23 and 5.24).

Fig. 5.18 Metal needle contained in the AVGFI System to avoid bubbles formation inside the bottle

4.The air pump is inside the same phaco machine; so there is no need to obtain it as an additional device (Fig. 5.17).

Internal forced infusion can be created with some other phaco machines that contain an air pump inside, like the Millenium Surgical System (Bausch & Lomb) [10] or the Oertly Phaco-Vitrectomy machine. Most of them are also hybrid systems, working for anterior and posterior segment surgery. Currently, new systems like Stellaris (Bausch & Lomb) are incorporating active air pump systems to improve fluidics performance.

5.3.1.2Surgical Features of the Accurus Surgical System Useful

for MICS Procedures

1. Internal air pump

The air pump is located inside the Accurus machine and the exit of air is located in the front panel in the lower portion of the machine (Fig. 5.17). An air filter must be placed to connect the air line to the bottle, with the objective to avoid contamination of the intraocular

metal needle that goes inside the bottle to avoid the formation of bubbles (Fig. 5.18), a drip chamber, and the plastic-tubing line for the infusion of intraocular solution.

The control of the amount of air expulsed by the air pump to create forced infusion is at the upper portion of the panel (Fig. 5.23); it can be digitally preset manually at the panel or at the remote control of the phaco machine. Two different settings can be programmed (Figs. 5.24 and 5.22) when starting; the Accurus machine has the advantage of allowing the surgeon to switch between both established forces of infusion during the surgery through the foot-pedal, with just a movement of the foot (Fig. 5.21), without the need to loose precious time changing the parameters at the panel or at the remote control [11].

With this system, the air exits from the air pump through the air filter, goes through the air tubing, enters to the bottle through the metal needle, forms a cushion inside the bottle according to the established force, and pushes the fluid through the drip chamber and the plastic line until the fluid reaches the irrigating device (chopper or cannula) located at the end of the line (Fig. 5.25). All of the mentioned parts of the system and their work conform to the system of internal forced infusion; it works with active hydrostatic force.

The rate of infusion will experience variations according to the force of air and the diameter of the irrigation device. The rate is measured by the amount of fluid that exits the irrigation device per unit of time (rate = ml × min). An ideal rate to perform a safe MICS procedure is around 45 ml/min (Fig. 5.20). The surgeon must keep in mind that when performing surgery, two more parameters must be taken into account (conforming both the outgoing fluid): the force of vacuum and the leakage through the incisions. So the surgeon must know the machine, the parameters, the instrumentation, and the construction of incisions, in order to maintain the surgery within the limits of safety [7, 8, 12, 13].

The air pressure is measured in the Accurus machine in centimeters of water (cmH2O), but can also be converted to millimeters of mercury (mmHg) according the preferences of the surgeon (Figs. 5.23 and 5.24). Also the surgeon must notice that for the creation of forced infusion, it is better to have the intraocular solution in a glass bottle (Fig. 5.18), so that the resistance of the material allows a true pressure; otherwise, the plastic bags have too much compliance in comparison

to the glass bottle and important differences in the hydrostatic pressure can be found, leading the possibility of surge during the surgery.

2. Phaco settings

The Accurus surgical system contains different phaco modalities, all of them corresponding to longitudinal energy. No torsional ultrasound has been incorporated to this machine by Alcon engineers until the time of writing this chapter; maybe this will happen in the near future. Nevertheless, the ultrasonic modalities are the same as that of other phaco machines; linear, continuous, pulsed, burst, or microburst, all depending on the software integrated in each machine.

The phaco tip can be used as the surgeon is accustomed to; nevertheless, we must remember that the ABS tips are not useful, because they may have leakage outside the eye, leading to important surge. An angled Kelman tip can be very useful; even if the Accurus machine does not have torsional ultrasound, the angle of the tip can facilitate the fragmentation of nuclear pieces [8].

New hand pieces, new tips, and new ultrasonic modalities are released time to time by the companies in order to increase the safety and efficacy of ultrasonic power; this parameter should always be updated.

3.Venturi-based aspiration system (so named because of Giovanni Battista Venturi)

Many surgeons worldwide are afraid to use venturi systems to create aspiration because they feel less controllable in comparison to peristaltic pumps. Many phaco machines have only peristaltic systems, but with time, the venturi system has been adopted by some other machines, and some of them are hybrid, containing both. The Accurus surgical system contains a venturi system to produce aspiration, and is very well digitally controlled; it has the advantage of being a direct system not depending on the compliance of the tubes and the movement of a peristaltic pump; when you want to stop, it really stops, and does not keep vacuum inside the tubes. Also the reflux does not depend upon the movement to the opposite side of the peristaltic pump, because it only pushes fluid in a reverse mode through the same aspirating tube; so it is a really controlled reflux, just exactly like the vitreoretinal surgeons are accustomed to use. Once the surgeon starts to work with venturi systems, he/she will