5.3.2Using the Alcon Infiniti and AMO Signature for MICS

Richard Packard

Core Messages

ßBoth the Infiniti and the Signature will allow the surgeon to perform CMICS and BMICS.

ßUnderstand the ultrasound delivery technology and choose a phaco needle suitable for your

needs. The Infiniti has Ozil and the Signature has Ellips.

ßFluidics requirements will depend on the phaco tip in use and so adjust them accordingly to

achieve best results. Smaller needles need higher settings.

ßRemember about leakage from incisions which is critical in both CMICS and BMICS. Excessive

leakage will cause the surgeon to alter fluidics settings unnecessarily.

ßOnce the cataract has been removed, woundassisted lens insertion is necessary to enable

incision size to be kept at a minimum.

5.3.2.1 Introduction

With the improvements in modulated ultrasound delivery and fluidics, smaller and smaller incisions for cataract surgery have become a reality for most surgeons. This chapter describes the way this author uses two of the machines (Alcon Infiniti and AMO Signature) that have been leading the move to MICS, whether it is biaxial or coaxial. The technology for ultrasound and fluidics as well as phaco tips available on these two machines will be discussed in different clinical situations using these smaller incisions.

5.3.2.2 Technology on the Alcon Infiniti

The Infiniti was introduced in 2003 with micropulsing and microburst capability, which means that ultrasound

R. Packard

Prince Charles Eye Unit, Windsor, England e-mail: mpacker@finemd.com

energy could be delivered in pulses of a few milliseconds. These could be used either as a continuous stream of these very short pulses of variable length and interval or at an increasing frequency up to a predetermined level. Both micropulse and microburst can be used in a linear manner to preset maximum power. The longitudinal tip movement which is traditional had torsional movement added to it in 2005. This appears to be a more efficient way of removing tissue, as there is almost no repulsion and better followability with lower aspiration flow settings. In addition, Alcon have now added the ability to set a lower as well as a higher threshold for power. This torsional phaco called Ozil is delivered in a linear manner but is measured differently from traditional phaco power; therefore, the power used is recorded as CDE (cumulative delivered energy). Ozil can be used as a continuous stream or in micropulse or burst mode. The author has reported that least energy is used in Ozil microburst mode at the expense of slightly increased foot pedal time in foot position three when compared with continuous Ozil. Micropulse Ozil seems to be the least efficient of the three modes. Although some recommend the use of a burst of longitudinal power in front of the torsional for denser nuclei, this author has not found it necessary. In order for Ozil to work effectively, some form of curved phaco needle is required to allow for the rotatory movement of the tip.

5.3.2.3 Setting Up the Infiniti for MICS

The parameters used depend on a number of different factors; the most import are, however, the phaco tip and the preferred irrigating chopper in case BMICS is used. Of course the height of the irrigation bottle will also influence the amount of fluid available to keep the anterior chamber stable. This author usually keeps the setting at 110 mm but the actual height, to be fully accurate, must be related to the position of the patient’s eye.

5.3.2.4Importance of Tip Size on Machine Fluidics Settings with the Infiniti

Alcon are offering a number of tip options for the Infiniti to be used for MICS and Ozil. However, the company is aiming at 2.2 mm incisions using CMICS as its flagship approach. Accordingly, there are both tips and sleeves

matched for this. The Ultra sleeve comes in two versions, a green one for the 1.1mm Flared Kelman tip and a pink one for the 0.9 mm Tapered Kelman, Mini-flared Kelman, Mini-flared 12° with up and down bevel tips. These are all ABS (aspiration bypass system) tips with a small hole drilled on the side that is supposed to assist in occlusion break control. These are not suitable for BMICS, however, because of the ABS port which may suck up the iris. All of the above tips have some sort of restriction in their diameter along the shaft to increase resistance to lessen the impact of occlusion break on the anterior chamber stability. The need for these sorts of changes is driven by the lower amounts of irrigation fluid entering the eye due to smaller incision sizes. The selection of CMICS tip becomes even more complicated as the 0.9 mm tips are available in both a 30 and 45° bevel. One of the disadvantages of restricted tips is clogging, particularly when harder cataracts are emulsified. In order to overcome this, a 45° tip which is a more efficient cutter works best. This author prefers to use a 30° Kelman non ABS non restricted tip for CMICS using the green Ultra sleeve (Fig. 5.28). The reasons for this are:

1.No clogging

2.Better tissue hold with less vacuum due to no leakage by the tip

3.Easier occlusion of 30° tip for chopping

4.Excellent cutting with Ozil

In order to improve fluid flow into the eye through the smaller incision, the author has designed a new tip for CMICS which can also be used for BMICS; it works

Fig. 5.28 0.9 mm Kelman tip in 2.2mm incision

with all phaco platforms. The basic shape is the standard 0.9 mm Kelman tip, but the overall diameter is reduced to 700 μm and the wall is very thin with an internal diameter of 570μm.

Owing to different internal diameters and the presence or absence of ABS with these different tips, the fluidics settings will vary to achieve the most efficient tissue removal and at the same time a stable anterior chamber. Table 5.4 summarizes the settings, this author uses for CMICS with these tips. The Infiniti has a function called Dynamic Rise which speeds or slows the pump speed on occlusion, according to the surgeon’s preference for a particular case or their skill level. The

Table 5.4 Settings for the Infiniti using a variety of tips available for CMICS and BMICS

settings that this author uses are included in the table. A Dynamic Rise of 3 will cause the pump speed to go up by 100% on occlusion to speed the time taken to reach maximum preset vacuum.

There is going to be a new sleeve called the Nano sleeve for CMICS at 1.8 mm, which the author has used extensively, and works very well with the same fluidics settings when the Mini-flared and 700μm tips are used (Fig. 5.29).

In order to assist further with minimizing the effects of post occlusion surge, Alcon have introduced new thicker, less compliant tubing as part of a whole package called Intrepid.

As with all MICS, getting the incision size right to minimize fluid leakage is critical which applies as much to CMICS as BMICS. The main source of leakage in CMICS is the side port incision. Accordingly, the author has designed a special, double ended, second instrument with a thickened shaft (Fat Boy Chopper, Duckworth and Kent, England) to fill the side port and lessen leakage (Fig. 5.30).

Fig. 5.29 700 μm Kelman tip in action with Fat Boy chopper

Fig. 5.30 Fat Boy chopper

This instrument is very versatile for cracking and chopping all sorts of hardness of cataract.

5.3.2.5Setting the Ultrasound Power and Modulation with the Infiniti for MICS

In order to perform both types of MICS safely, it is important to use some form of power modulation to minimize heat rise in the wound. Although this is more important in BMICS, it becomes more of an issue in CMICS than conventional coaxial phaco because of the thinner sleeve and tighter wound. Ozil, even in continuous form, produces much less heat rise in the tip than longitudinal phaco. The author uses it in continuous linear form with a preset maximum of 50% for soft and medium nuclei and 100% for dense ones. This is just to sculpt a small hole in the nucleus to allow the Kelman tip to bury deep in the nucleus for chopping. For the actual chopping and segment removal the settings are changed to microburst Ozil as mentioned above. The on time for the burst is 35 ms and the off time when the foot pedal is fully depressed is 40 ms. The maximum power is set at 100%. This sort of setting will produce CDE readings of the order of 2–3 for soft cataracts, 6–7 for medium and up to 25 for really dense ones. Using continuous Ozil for segment removal will lead to much higher energy usage which is not necessary.

5.3.2.6 The Infiniti and BMICS

Although Alcon as a company have been much more active in pushing the CMICS agenda with a 2.2 mm incision, the Infiniti can be used perfectly well for BMICS. The author first used it in that way in 2004 and it works well with Ozil also using the non ABS 0.9 mm Kelman tip. As with all BMICS, an irrigating chopper is required and the design and size of this is critical to the machine settings (Fig. 5.31). Irrigating choppers vary considerably as to the amount of irrigating fluid that they are capable of releasing. It is important to choose a chopper that gives at least 60 ml/min. With less than this, the machine fluidics settings will need to be considerably reduced to maintain a stable anterior chamber. This author has designed a chopper with a flow rate of over 80 ml/min, thus the fluidics settings as in Table 5.4 do not need altering.

Fig. 5.31 Packard irrigating chopper (Duckworth and Kent, England)

As with all BMICS, part of the balance is about getting the incision sizes right for the instruments going into the eye. The 0.9 mm phaco needle goes through 1.4 mm incision and the chopper through 1.6 mm both of these being the internal diameter of the wound. Ideally a trapezoidal wound should be created to allow instrument movement without damaging the wound and making closure at the end of the operation an issue.

5.3.2.7Technology for MICS on the AMO Signature

In 2001 on the AMO Sovereign phaco machine, the previous model to the Signature, White Star power modulation using micropulsing was introduced for the first time. This was then further modified 2 years ago with ICE (increased control and efficiency). This was a means of adding a 1 ms punch at the beginning of each pulse of phaco energy at a higher power. The punch could be programmed to stay the same as the energy increases, or be either increased or decreased as the rest of the energy is increased. The object was to allow for enhanced cavitation by pushing a piece of nucleus away and allowing BSS (balanced salt solution) to enter the space created. Since cavitation largely occurs above 70% power settings and certainly this author uses only 40% power settings, it is debatable whether, even if this actually takes place, it is beneficial. It would be difficult to show any difference between the various settings for ICE that would help this debate. As on the Sovereign there is a range of pulse settings. It is useful to be able to use different settings for the tip in both occluded and unoccluded

modes. The note of ultrasound delivery changes as the tip occludes and long before the maximum preset vacuum is reached. There is no dedicated sleeve for CMICS available for the Signature; however, the existing yellow sleeve works well with an incision size of 2.2 mm. This is of course not important for BMICS where the sleeve is irrelevant, except to reduce spray from the phaco needle.

Issues around repulsion of nuclear material which had been a driver for other systems have also been addressed on the Signature by the introduction of a lateral movement of the phaco needle; here, it is also accompanied by a longitudinal movement. 50% of the available power goes to longitudinal and 50% to lateral movement. This is called Ellips™ to describe the sort of movement that the tip is making. It does not require a Kelman style needle to work unlike torsional movement on the Infiniti. The division of the power delivered into two components means that the settingsneedtobealteredconsiderably.Approximately double the settings are recommended, i.e., if the longitudinal setting is for 40% power, raise this to 80% for Ellips. Further, the pulse settings need to be altered to have a much higher duty cycle to be able to sculpt hard nuclei and get good burying of the tip for chopping, to remove hard nuclei. This author’s initial experience has indicated good followability compared to longitudinal alone and reduced repulsion. However the ability to cut into dense nuclei and bury the tip even with a Kelman phaco tip does not, with current settings, seem to be as good as conventional longitudinal phaco on the Signature, when pulse settings with White Star are used. As with Ozil on the Infiniti, using the Ellips technology in continuous mode works better for some parts of nuclear removal, such as sculpting and starting to bury the phaco needle for chopping.

The Signature has a development of the fluidics control seen originally on the Sovereign called CASE (chamber stabilization environment). Here in order to help post occlusion surge, the chosen vacuum in segment removal mode can be held for a time limited period of up to 3 s. Various thresholds can be set for different events in the raising and lowering of vacuum. This can be done on the screen of the Signature in an active manner by moving a cursor. It customizes the machine responses to the individual surgeon’s technique and needs in a given operative situation (Fig. 5.32).