Routine Use of Microcoaxial Torsional Phaco

Since this past summer, my routine cataract procedure is 2.2-mm microcoaxial torsional phaco, using the Infiniti Vision System with the OZil handpiece (Alcon Laboratories, Inc., Fort Worth, Texas), an ultrasleeve mini-flared 45º Kelman tip (Alcon Laboratories, Inc.), and thin-walled bimanual I/A cannulas (Duckworth & Kent, Ltd., Hertfordshire, England).

MY ROUTINE PROCEDURE
Incisions. After creating (1) two 0.9-mm sideport incisions at 2 o'clock and 9 o'clock and (2) one half-depth initial groove for the main incision at 11 o'clock using a 22.5º knife, I inject Viscoat (Alcon Laboratories, Inc.) through one sideport. This provides me with the exact required IOP to create a perfect tunnel of the desired length and wound architecture. I use a HP2 2.2-mm double bevel nonside-cutting blade (Alcon Laboratories, Inc.).

Capsulorrhexis. After penetrating the anterior chamber, I make a capsulotomy with this sharp blade. You do not need another sharp instrument for the initial cut into the anterior capsule. The sharp blade does not have a stressing effect on the zonules. I then create an approximately 5.0-mm capsulorrhexis with the Inamura style capsulorrhexis forceps (Duckworth & Kent, Ltd.).

Hydrodissection. Hydrodissection is performed with a curved and tapered 25-gauge cannula (Steriseal, Oirschot, Netherlands). It is placed at 3 o'clock, with subsequent depression of the nucleus to loosen the anterior capsular fiber attachments at that location. At 180º apart from the hydrodissection, depression of the nucleus will loosen the opposite anterior fibers. In almost all cases, I can rotate the nucleus freely after this double depression maneuver. Loosening the nucleus from the anterior capsule is the key point of these maneuvers.

Fast Crack. I use the OZil handpiece and ultrasleeve mini-flared 45º Kelman tip, in continous mode with 80% linear torsional power; a 75 cm bottle height; 20 mL/min aspiration flow; and 90 mm Hg vacuum to sculpt a groove in two to three passes. Torsional ultrasound is extremely effective in cutting nuclear material. The mini-flared phaco tip (Alcon Laboratories, Inc.) has a 50% higher amplitude of swiping motion at the tip end, compared with the most widely used tapered tips for torsional ultrasound.

I perform a hemi-crack by placing the phaco tip and a Bechert fork (Wilhelm Julius Teufel GmbH, Stuttgart, Germany) deep in the center of the groove. Subsequently, I make a downward sweeping motion with the fork away from the phaco tip, cracking the nucleus in half. Turning the nucleus 90º clockwise, I embed the tip deep into the nucleus just below the center, and introduce the fork underneath the tip into the same space (ie, created when the tip is embedded). I sweep the fork sideways by gently rolling it between my fingers. Compared with traditional divide and conquer, this fast crack technique tremendously reduces ultrasound energy; it is actually not difficult to perform. I repeat this fast crack maneuver until I get four freely mobile quadrants.

Quadrant Removal. I have recently changed my settings for quadrant removal; I only use torsional ultrasound in burst mode (ie, 70% fixed torsional ultrasound power for 20 milliseconds), no longitudinal ultrasound, 75 cm bottle height, 25 mL/min aspiration flow, and 350 mm Hg fixed vacuum. These settings are much lower than my past settings during traditional ultrasound with the tapered tip, microsleeve, and 2.6-mm incision. For this procedure, I previously used 100 cm bottle, 450 mm Hg vacuum, and 45 mL/min flow.

Torsional ultrasound is more efficient compared with traditional longitudinal ultrasound, and my total procedure time is reduced by 25%, despite these low and conservative settings. Fluid turbulence is dramatically reduced, protective viscoelastic is much better retained during emulsification, and the corneal endothelium is better protected. Therefore, torsional ultrasound is beneficial for postoperative corneal clarity and patient outcome.

Ozil BURST MODE ADVANTAGE
When using only torsional ultrasound in burst mode with 70% fixed power (20 milliseconds), the difference between foot positions two and three are noticeable. With continuous linear torsional ultrasound, however, one cannot feel or hear this difference. Therefore, the surgeon may have difficulties maintaining holding power, because of inadvertent occlusion break when stepping on the footswitch in position three.

Until approximately 60% torsional power, it is not very noticeable that the torsional ultrasound is activated, but it does break up lens material effectively. To engage the first quadrant, I embed the nuclear piece from the side, holding the phaco tip sideways. With this horizontal approach, the tip does not approach the posterior capsule. With a few short 20 millisecond bursts, one can embed the tip quite easily; going back to foot position two, you can get a good grip with the 350 mm Hg fixed vacuum, and then pull the nuclear piece toward the center to be emulsified. The three remaining quadrants are evacuated in the same way.

Bimanual I/A. Cortex removal is performed with thin-walled cannulas (Duckworth & Kent, Ltd.). The aspirating cannula has a somewhat depressed and rounded aspiration port that reduces the risk of posterior capsular tear. I actually prefer silicone I/A for its safety profile (See Silicone-coated Soft VA Tip, page 26), but it is not yet available for a bimanual I/A technique. Fluidics settings have to be lower, because of the low irrigation flow (ie, approximately 25 mL/min with 75 cm bottle height). I use 500 mm Hg vacuum and 12 mL/min aspiration flow.

I use a separate low vacuum setting (ie, 50 mm Hg vacuum and 10 mL/min flow) to remove thin fibers. For posterior capsular polishing, I use 5 mm Hg and 10 mL/min linear flow.

IOL injection. Our routine IOL is the aspheric Acrysof SN60WF (Alcon Laboratories, Inc.). After loading the IOL into the Monarch II C-cartridge (Alcon Laboratories, Inc.) with the Grieshaber loading forceps (Alcon Laboratories, Inc.), a wound-assisted injection technique is performed with the Monarch II injector after injection of ProVisc (Alcon Laboratories, Inc.).

When operating from the superior position, counter traction is not needed for IOL injection, as the automatic upward movement of the globe provides sufficient counter force. If a temporal located incision is made, a single-hand injector with a second instrument for counter traction is probably a better option.

The wound-assisted technique through a 2.2-mm incision requires some understanding of potential pitfalls. Most frequently, a halted injection and subsequent decompression of the optic inside the wound, or a haptic or optic edge hitting Descemet's membrane, will prevent successful and smooth injection into the anterior chamber. Once the pearls and pitfalls are mastered, this technique is not very difficult. I would recommend that surgeons who wish to reduce their incision size gradually taper down wound size. Start at 2.8 mm, and take the next step to 2.6 mm, 2.4 mm, and finally 2.2 mm, after feeling comfortable with making that particular incision size (Figure 1).

Viscoelastic removal and IOL positioning. I remove the ProVisc from both anterior as well as posterior of the IOL. The flexible haptics of the Acrysof single-piece allow for easy manipulation and access to the space behind the optic of the IOL.

I always position the IOL in the center, with possibly the capsulorrhexis edge covering the entire optic. Finally, the two 0.9-mm sideport incisions need to be hydrated to ensure closure of these very small incisions. The main incision, however, generally requires no stromal hydration or stitch. The three-step architecture of the wound, in combination with no significant wound stretch by either phaco tip or IOL injection, results in safe and watertight incision closure (Figure 2).

MICROCOAXIAL TORSIONAL PHACO SUMMARY
The development of torsional ultrasound with the OZil handpiece, ultrasleeve, and mini-flared tip has converted me entirely to 2.2 mm surgery. I did not need to change my technique in any way or buy expensive instruments. My surgical procedure time has remained the same, and my feeling of safety has increased, due to the possibility of significantly reducing fluidics parameters without compromised efficiency.

Further innovations of cartridge designs will increase the ease of IOL injection. This will drive many surgeons to convert to 2.2-mm microcoaxial surgery (Figure 3) in the future.

Khiun F. Tjia, MD, is an Anterior Segment Specialist at the Isala Clinics, in Zwolle, Netherlands, and an Associate Clinical Professor affiliated with the University of Groningen, in the Netherlands. Dr. Tjia is the Co-Chief Medical Editor of CRSToday Europe. He states that he is a research consultant for Alcon Laboratories. Dr. Tjia may be reached at kftjia@planet.nl.