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Innovations | Apr 2008

How to Perform B-MICS in 2008

The division of irrigation and aspiration provides more intraoperative control.

Today, innovations and technology rule the organization of our surgical practices. Peyton's training circle (Figure 1) reminds us that with every change we make comes a consequence—the transition from unconscious abilities to unconscious incompetence before we progress to conscious competence. With that in mind, why should we update our surgical habits, which require training, a learning curve, and investment in time and materials? Herein lies my answer as to why I switched to microincision cataract surgery (MICS) and my technique of choice.

After the work of Hiroshi Tsuneoka, MD, of Toyko, and Amar Agarwal, MS, FRCS, FRCOphth, of India, in the 1990s and Jorge L. Alió, MD, PhD, of Spain, in 2000, I was interested in biaxial MICS (B-MICS).1 Certainly, the prospect of creating a 1.2-mm microincision seemed the main motivator; however, I also quickly realized that the division of irrigation and aspiration was more favorable in terms of safety and visual recovery. B-MICS is more accurate, less traumatizing, and permits safe phacoemulsification in difficult cases, including patients with a shallow anterior chamber, miosis, or intraoperative floppy iris syndrome.

ADOPTION OF B-MICS
I perform 100% of my operations with B-MICS and have had good results. Other ophthalmologists, however, do not seem as convinced of its benefits. Only 5.2% and 18.2% of US and European surgeons, respectively, use B-MICS. Among the US surgeons who use B-MICS, 25% use it as their exclusive cataract surgical technique, and 33% of the European surgeons who use B-MICS use it in at least half of their cases (personal communication with David Leaming, MD; 2006-2007 data). In my country, France, only 2.32% of surgeons practice B-MICS.2

In an analysis of available MICS platforms in Europe, the most popular were the Infiniti Vision System with Ozil (Alcon Laboratories, Inc., Fort Worth, Texas), the Stellaris (Bausch & Lomb, Rochester, New York), and the WhiteStar Signature (Advanced Medical Optics, Inc., Santa Ana, California) (personal communication with Leaming; 2005 data).

B-MICS is slowly gaining approval, and 45.3% of European surgeons who do not currently practice B-MICS are interested in the procedure. Approximately 30% of European surgeons who do not currently practice B-MICS hope to begin in the near future; 50% of these favor the Sovereign phaco system (personal communication with Leaming; 2005 data).

These data may suggest that even if surgeons are not using B-MICS, it may be due to lack of access to the technology rather than not agreeing with the concept. Several companies are reacting to this situation, and research and development departments are working to increase their compaines' MICS product lines.

For example, in 2005, Alcon Laboratories, Inc., launched its microcoaxial technique, which permits surgeons to perform MICS without significant modifying their technique. Additionally, Alcon designed the Ozil handpiece for torsional phacoemulsification, and Advanced Medical Optics, Inc., updated its system with WhiteStar Signature software that uses more occlusion and less ultrasound. The company has now launhed the Signature phaco system. New implants and injection systems for mini-incision (between 2 and 2.8 mm) or microincision (sub–2-mm) surgery have also been designed.

MY TECHNIQUE
I have found that the learning curve for B-MICS is short because surgeons are already used to working with both hands. Most surgeons will find that their procedure time does not increase. In fact, it should be similar in length to most coaxial procedures.3 In my hands, a typical B-MICS case proceeds as follows: I use the Sovereign WhiteStar Increased Control and Efficiency (ICE) system, which includes its Sovereign Chamber Stabilization Environment (CASE; Figure 2) software. This environment allows a vacuum level, to be defined in advance (ie, up threshold), which reacts within the first 26 milliseconds before the infusion break. The system can then return to the down threshold, avoiding surge. The CASE perfusion line is 15 cm longer than the previous perfusion kit, which permits the use of high vacuum and allows a 40% higher flow rate at the same perfusion level. Surge is also avoided with this kit. The perfusion tube (Figure 3), constructed of PVC, is 5-mm, lightweight tubing that increases flow from 120 cc/minute to 167 cc/minute. This modification of the perfusion line, in association with the WhiteStar ICE technology, permits a very high vacuum (500 mm Hg) without surge.

I can also increase the total power of the pulse from 0% to 12% within the first millisecond of the procedure using the WhiteStar's Kick System.

One important tool for any cataract procedure is the surgical knife. In conjunction with PhysIOL (Liége, Belgium), I developed the MicroCut (Figure 4), a knife adapted for micro- and mini-incision surgery that creates 1.2-, 1.8-, 2.2-, and 2.4-mm incisions.

Another important tool, the hydrochopper, allows balanced flow and an accurate phaco chop and avoids capsular trauma. Hydrochopper tubing with a slim lining, such as 20-gauge tubing, creates a flow rate of approximately 45 cc/min.

Unfortunately, most hydrochoppers exceed this tube diameter, and a capsular break is probable if the chopper comes in contact with the capsule. Therefore, I have designed two hydrochoppers, with 0.4-mm (Lesieur Horizontal Hydrochopper; Katena Products, Inc., Denville, New Jersey; Figure 5) or 0.8-mm (Lesieur Vertical Hydrochopper; Katena Products, Inc.) tips. Both choppers allow a safe chop of the nucleus. A beveled tip permits easy insertion into the anterior chamber, and two lateral ports were avoid surge during chopping when the coaxial opening is closed. I choose which of these hydrochoppers to use during my B-MICS procedures.

My IOL of choice is the MicroSlim (PhysIOL; Figure 6), which is a 25% water content hydrophilic acrylic design that is more compressible than the company's SlimFlex design. This modern IOL design has a 6.15-mm optic, a 360° square-edge design, and 5° posterior haptic angulation.7-9 It fits through a 1.8- to 1.9-mm incision (Figure 7), regardless of IOL power. Additionally, a Medicel 1.8-mm injector (Medicel AG, Luchten, Switzerland) may be used to insert the lens through an enlarged 1.8- to 1.9-mm incision. Minicoaxial phaco may alternatively be performed through a 2.2-mm incision.

Following are some of my pearls for B-MICS: Separation of irrigation and aspiration is essential to provide the best efficiency, less repulsion of nuclear fragments, and reduction of effective ultrasound time.4 Surgical complications are the exception but easily managed when they occur because you can advance to fragment removal when capsular break occurs. My steps to avoid complications during the learning curve of MICS are outlined in Avoiding Complications.

When using the Sovereign WhiteStar system, the phaco handpiece remains the same for both C- or B-MICS; however, if the Infiniti with Ozil is used, the handpiece must be switched.

There is no doubt that the evolution of MICS permits less invasive and less traumatic surgery. By employing less ultrasound and creating narrower incisions, biaxial phacoemulsification is a more secure and accurate procedure compared with C-MICS. It has opened the way for other emergent technologies, including minicoaxial phaco and the Ozil handpiece. Complications become the exception and are easily managed with B-MICS. In my hands with B-MICS, my patients achieve excellent results and are happy with faster visual recovery.

Gilles Lesieur, MD, is an Anterior Segment and Refractive Surgeon at the Centre Ophtalmologique Iridis, Albi, France. Dr. Lesieur states that he is a paid consultant to and receives a royalty from PhysIOL. He may be reached at g.lesieur@iridisinnov.fr.

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