Cataract surgeons worldwide are gaining more interest in microcoaxial phacoemulsification. In return, manufacturers of phacoemulsification equipment have been introducing new hardware and software options for 1.8- to 2.2-mm incision cataract surgery. One such introduction in Europe is new microincisional IOLs.

The concept of an integrated microincisional approach that matches the required incision size for IOL injection is very logical. An incision size of approximately 2 mm is already astigmatically neutral. Anything below a 1.8- to 2.2-mm incision size (ie, bimanual phaco) requires either enlargement of a primary incision or a new incision for IOL injection.

Two major companies have recently launched relevant microcoaxial phaco products. Bausch & Lomb (Rochester, New York) first released its new Stellaris MICS 1.8-mm procedure and its Akreos MI60 hydrophilic acrylic IOL during the American Society of Cataract and Refractive Surgery (ASCRS) Annual Symposium and Congress, in San Diego. The company then launched its products in Europe during the XXV Congress of the European Society of Cataract and Refractive Surgeons (ESCRS) in Stockholm, Sweden. Successful injections through 1.8-mm incisions with limited wound stretch are reported from several surgeons, and I also have found limited wound stretch with the 1.8- to 2-mm incisions. It will be interesting to see long-term posterior capsular opacification rates for this innovative microincisional IOL design.

Microcoaxial torsional phacoemulsification with the Infiniti Vision System phacoemulsification machine and OZil handpiece (both manufactured by Alcon Laboratories, Inc., Fort Worth, Texas) has been described many times. Surgeons typically mark this procedure as having an easy transition to 2.2-mm phaco with torsional ultrasound technology. AcrySof IQ IOL injection with a Monarch II C-cartridge (both manufactured by Alcon Laboratories, Inc.) through a 2.2-mm incision, however, has come with a learning curve for some surgeons. An incision size of 2.4 to 2.6 mm is realistic for routine use. Several colleagues, however, have been using this injector with 6-mm AcrySof IOLs for microincisions as small as 1.8 mm.

D-CARTRIDGE AND MONARCH III INJECTOR
The Monarch III D-cartridge (Alcon Laboratories, Inc.) and injector for 2.2-mm microcoaxial phaco were also launched at the recent ESCRS Congress. This cartridge is significantly smaller compared with its predecessors. Its loading dock is 6 mm wide, in contrast to the 5.5-mm loading zone of the C-cartridge. Loading 6-mm IOLs is, therefore, much easier with D-cartridge (Figure 1). The cartridge tip is easily introduced into approximately two-thirds of the corneal tunnel (Figure 2), and the wound-assisted injection is much easier than with the C-cartridge.

The Monarch III D-cartridge is validated for injection of the thinner aspheric AcrySof SN60WF IOL, up to 27.00 D. My initial experience with the D-cartridge was very favorable, and surgeons should be able to transition to microcoaxial phaco and IOL injection much easier than with the Monarch II C-cartridge. The injection requires much less pressure of the cartridge tip to the wound. A great advantage with this smaller cartridge is that 2.2-mm incisions are not significantly stretched. Pre- and postinjection wound size measurements with internal calipers have shown minimal or no wound stretch and enlargement (Figure 3).

During a live surgery event at the XXV ESCRS Congress, Alan S. Crandall, MD, of Salt Lake City, Utah, demonstrated microcoaxial surgery with the new Intrepid FMS (Alcon Laboratories, Inc.), a significantly lower compliance tubing system compared with the original FMS system. Contraction/expansion of aspiration tubing in response to occlusion break (high vacuum) is a main contributor to surge flow, which in turn is the main cause of anterior chamber instability. It is, therefore, logical to minimize surge flow by reducing the compliance of the aspiration tubing. With the Intrepid FMS, surge flow volume on occlusion break is significantly lower than with the original FMS (Figure 4).

At the moderately high vacuum levels (ie, 300–400 mm Hg) currently used with torsional ultrasound, the surge flow volume is extremely low with Intrepid FMS. This results in good anterior chamber stability and further increases the margin of safety. The vacuum rise time is approximately twice as fast. The responsiveness of the Infiniti with Intrepid FMS is impressive, even with low-to-moderate fluidics settings (Figure 5).

Torsional ultrasound requires the use of a Kelman bend-tip design. The 20º bend results in an effective transverse movement at the end. The movement (ie, friction) inside the incision is restricted, and it therefore induces less heat. Many surgeons, however, feel uncomfortable changing from a straight-tip design to the 20º Kelman tip. Alcon Laboratories, Inc. will soon launch a new 12º bend Angled Mini-Flared design. This 12º bend tip will feel much like a straight tip, however, it will still retain the efficiency benefits of torsional ultrasound (Figure 6). This new tip will make many surgeons more comfortable when transitioning from longitudinal to torsional ultrasound.

More progress to improve the performance of cataract surgery equipment and IOL injection systems will be made by all companies. Microincisional cataract surgery will probably be widely adopted in the near future.

Khiun F. Tjia, MD, is an Anterior Segment Specialist at the Isala Clinics, in Zwolle, Netherlands. Dr. Tjia is the Co-Chief Medical Editor of CRST Europe. He states that he is a research consultant for Alcon Laboratories, Inc. Dr. Tjia may be reached at kftjia@planet.nl.