MICS instrumentation growing in versatility, variety

The instruments have a learning curve, as does the procedure, practitioners say.

Surgeons are increasingly expressing interest in microincision cataract surgery, and instrument companies have moved swiftly to accommodate that interest. Most companies that make hand-held instruments for cataract surgery have recently introduced a line of 20-gauge instruments to be used in bimanual procedures.

Debates may remain about the efficiency of microincision cataract surgery (MICS) or the appropriate IOLs to be used, but there is no doubt that instruments to perform the surgery are proliferating.

Whether the procedure is called bimanual phacoemulsification, MICS or phakonit, the basic idea is the same – to increase surgeon control and improve surgical outcomes by keeping incisions smaller, reducing fluctuations in the anterior chamber with better fluidics and tighter wounds. The procedure relies on the use of two cataract incision of less than 2 mm, through which separate irrigation and aspiration handpieces are passed.

Splitting up I&A requires relearning on the part of surgeons and, just as significantly, retooling on the part of manufacturers. After 30 years of phaco through one 3-mm incision, suddenly engineers are faced with a new paradigm: instruments half the size, with their functions split and new functions – such as chopping – added on.

Many instrument manufacturers have risen to the challenge. To review the host of new 20-gauge products that have entered the market in the past few years, Ocular Surgery News spoke with physicians using 20-gauge instrumentation from a variety of companies.

The products range from specialized phaco tips to knives, scissors and forceps. In addition to the information and interviews below, please refer to the Guide to Hand-Held Cataract Instrumentation in the print edition.

Rapid adoption

Because no lenses that fit through an incision of less than 2 mm are currently available in the United States, it might be thought that U.S. surgeons would be reluctant to adopt MICS. But according to the most recent poll by David V. Leaming, MD, interest in the technique is growing rapidly. In his 2003 survey of U.S. members of the American Society of Cataract and Refractive Surgery, 16.5% of respondents said they are currently doing bimanual phaco regularly, and another 20% said they plan to adopt it in the coming year. Dr. Leaming announced these findings at the recent ASCRS meeting in San Diego.

U.S. surgeons who have adopted the technique can use the microincisions only for cataract removal. Either one incision must be enlarged or a separate larger incision made to accommodate a standard foldable IOL.

Roger F. Steinert, MD, is one U.S. surgeon who has adopted MICS. He said he uses the microincision technique because it allows tighter wounds and better fluidics control. He said it is important to use a knife that can create a small tunnel-shaped incision to facilitate putting the instruments through. He makes a separate third incision for IOL insertion.

Another early adopter of MICS, David F. Chang, MD, noted that, “for the curious surgeon who would like to experiment with this technique,” the investment need not be extensive.

“One needs a 1.2-mm metal keratome, the $15 disposable Cruise Control device from STAAR Surgical and a 20-gauge irrigating chopper,” Dr. Chang said. “In the beginning, I suggest that surgeons still make a 2.8-mm incision initially and place their two microincisions to either side.”

He said the 2.8-mm incision can be used not only for IOL insertion but also for performing capsulorrhexis and hydrodissection in the usual manner. It also makes it easier to convert back to standard coaxial phaco at any time during the case, he noted.

Accutome

When no instruments were available to fit his cataract technique, Felipe Vejarano, MD, said, he designed his own. The Natural Clear Cornea Vejarano Micro-incision knife, from Accutome, is a 20-gauge diamond knife. The Vejarano Irrigating Chopper, also made by Accutome, has a polishing tip for the posterior capsule, Dr. Vejarano said.

“On the end of the chopper, there is a tiny ball to protect the posterior capsule from collapse,” he said.

The chopper has a keel with a sharp internal blade to penetrate into the nucleus, facilitating removal of even hypermature cataracts, Dr. Vejarano said. The device has a superior curve to protect the anterior capsule when the instrument is inserted. He said the device’s size, 1 mm to 1.1 mm, fits a 1 mm lateral paracentesis and keeps the incision watertight. It has two holes for lateral irrigation to avoid turbulence, he said.

“With all of these chop maneuvers, there is never occlusion impeding sufficient flow to the eye, which enters at 42 cc/min,” he said.

ASICO

Mark Packer, MD, said he is working with ASICO on the development of a microphaco diamond knife, capsulorrhexis forceps and a new irrigating chopper. He said one identifying factor of the diamond knife is its sharp, straight tip.

“It doesn’t come to an absolute point at the tip. … It consistently makes a clear corneal tunnel incision that’s 1.2 mm in diameter and about 2 mm in length, which is just perfect,” he said.

He uses the Fine Ikeda capsulorrhexis forceps from ASICO, designed by his colleague Dr. Fine. Quality forceps are necessary to maintain corneal structure and avoid stretching the wound to assure closure, he said.

“You initiate the rhexis with a little pinch. You pinch the capsule and pull slightly to the left or right. It will initiate a perfect little tear every time,” he said.

The forceps assist in keeping control while making the opening, which is important for IOLs requiring a smaller capsulorrhexis, he said.

The irrigating chopper can be used for horizontal or vertical chopping and is suitable for removing soft and hard nuclei, Dr. Packer said.

Bausch & Lomb

Bausch & Lomb manufactures trapezoidal diamond blades, hydrodissection cannulas and aspirating choppers appropriate for use in MICS.

Rosa Braga-Mele, MEd, MD, FRCSC, said she prefers Bausch & Lomb’s diamond knives for making clean, precise incisions. She said she also likes the Gimbel Hydrodissection Cannula.

“I find it always gives me consistent fluidics for hydrodissection,” she said.

The Braga-Mele Irrigating Chopper is 19-gauge instrument that allows between 35 cc/min and 40 cc/min fluid flow, she said.

She also uses Bausch & Lomb vertical and horizontal choppers.

“I like the duel irrigating ports … it gives me more control in the eye over my fluidics. Some would say that the single irrigating port would give you more fluid flow, and I agree … but I find it harder to control exactly where the fluid flow is going … that’s why I prefer the Bausch & Lomb one,” Dr. Braga-Mele said.

She also a Sweeney paddle-ended nucleus manipulator on the end of an irrigating instrument, she said.

She uses all these devices on the Bausch & Lomb Millennium Microsurgical System with a Microflow needle on the phaco handpiece with no sleeve. The handpiece has a 1.1 mm outer diameter, she said.

Geuder

Amar Agarwal, MD, the developer of the microincision technique he calls phakonit, has designed instruments for the technique with several manufacturers, including the German company Geuder.

The Agarwal Irrigating Nucleus Chopper from Geuder has a sharp cutting edge and point, Dr. Agarwal said, which is usable for all types of cataract removal techniques.

The Agarwal Globe Stabilization Rod and Nucleus Manipulator incorporates a rod to stabilize the eye and a Y-shaped fork to rotate the nucleus, he said.

“If one is doing no anesthesia or topical anesthesia, then by stabilizing the eye from the inside with the rod, one can move the eye in any direction without producing pain or subconjunctival hemorrhages to the patient, which would happen if one uses forceps to hold the conjunctiva,” he said.

The Agarwal Karate Chopper has a sharp chopping edge that can be used on any type of cataract, he said.

Other Geuder products appropriate for MICS include the Brauweiler Irrigating Cannula Handpiece.

HUCO

HUCO makes the Agarwal phakonit chopper and an irrigating chopper designed by Dr. Agarwal. The company also has a new chopper for use with Alcon phaco systems, which is expected to enter the market soon, according to a company representative.

HUCO makes a number of knives for temporal clear corneal incisions, Dr. Agarwal said.

“One of the main problems in phakonit was to create the temporal clear corneal incision,” he said in a recent article describing his technique.

Dr. Agarwal said HUCO makes a sapphire knife that can create a 1.2 mm valve incision that is effective for MICS.

“The HUCO Phakonit knives are terrific as they give good valve construction,” he said.

Kirwan

Kirwan has a number of reusable and disposable separate I&A instruments appropriate for bimanual surgery, said Kate Ward, marketing associate for Kirwan Surgical Products.

Kirwan’s irrigating handpiece is available in sizes from 21-gauge to 23-gauge with a 0.5 mm irrigating side port, she said. The aspirating handpiece is available in 23-gauge with a 0.3 mm aspirating port.

Katena

Katena also has an extensive line for use in MICS. Jorge L. Alió, MD, PhD, who coined the term MICS, has been the primary designer for the Katena 20-gauge product line. He said the company’s knives are designed to create trapezoidal incisions to maintain fluidics, a crucial element of the procedure.

“Also important is the forceps design for the microcapsulorrhexis. Once placed, it allows for more maneuvering during MICS,” he said.

Dr. Chang has tested and designed instruments for Katena as well. One of the instruments he designed is the Katena Chang Hydrochopper, which has a long, slender tip.

“I find it preferable for this reason. Since the irrigating lumen occupies a certain width, I find that the extra tip length of the Katena Hydrochopper is invaluable for horizontal chopping,” he said.

He prefers front-irrigating choppers, such as those made by Katena and MicroSurgical Technology (MST).

“Front-irrigating choppers deliver more inflow than side-irrigating choppers of the same external diameter,” he said.

With these 20-gauge instruments, he uses a 1.2 mm keratome to produce a tight incision.

Mastel Precision

Mastel Precision produces sharp, 20-gauge diamond knives with an easy locking mechanism, said L. Andrew Watkins, MD.

The type of incision made is essential for successful MICS outcomes, Dr. Watkins said. If the incision is smaller than the instrument, there can be oar-locking, wound stretch and tearing of Descemet’s membrane, resulting in poor wound closure. If the incision is too large, there could be wound leakage and poor chamber stability, he said.

The smoothness of these instruments’ finish is important for patient safety and successful outcomes, Dr. Watkins said. He recommended examining the finish under maximum magnification.

“The instruments are superbly finished with a very smooth finish on the edges of the aspiration port, which is important to prevent rupture of the posterior capsule when the capsule is aspirated,” Dr. Watkins said.

He said he uses the Fine 1.2/1.4 mm ParaTrap blade to make an appropriately sized incision to fit 20-gauge phaco tips and I/A handpieces.

Dr. Watkins also uses Mastel’s bimanual I&A handpieces. The handpieces, with 0.8 mm and 0.9 mm outside diameters, are smaller and easier to use than others on the market, he said.

Microsurgical Technology

MST has one of the more extensive product lines for MICS. Its Duet line contains a selection of tips for use in capsulorrhexis, chopping and other functions. The company also has a “soft” irrigation and aspiration (I&A) tip with a silicone sleeve for use with both bimanual and coaxial systems.

“What MST has done extremely well is to make a light and ergonomically nice handpiece that basically has a universal adapter for a wide range of chopping and nucleus manipulating tips,” Dr. Steinert said.

The MST instruments, which are also distributed through Advanced Medical Optics, have the I&A functions separated, and each tip is color-coded to facilitate switching, Dr. Steinert said. The devices can be used with the AMO Sovereign system with WhiteStar technology. This “cold phaco” technology allows phaco to be performed without an irrigation sleeve. “That reduces the bulk from 3 mm to a little over 1 mm for a 20-gauge needle,” Dr. Steinert said.

Dr. Agarwal and Dr. Chang have also developed instruments for MST.

Dr. Agarwal said the 20-gauge irrigating chopper he designed with MST is appropriate for chop techniques, even for removal of hard cataracts.

Rhein Medical

The knife is one of the most important instruments for MICS since it determines the type of incision through which the operation will be done, said I. Howard Fine, MD, who has designed instruments for Rhein Medical, MST, Mastel and Katena.

“We’ve worked with all of these on different phaco systems with great success,” Dr. Fine said.

He said he likes the Rhein Medical 3-D diamond blade, which is self-directed.

Carlos Verges, MD, PhD, designed the Verges Irrigating Chopper with Rhein. It has a polishing tip, which gives the device a dual function.

“With respect to the chopper, the principal advantage is the ability to arrange the irrigation and the manipulator at the same time. I think it’s necessary to have a combination of these two aspects, the ability to manipulate, remove and cut the cortico-nucleus, and at the same time guarantee sufficient irrigation to compensate the fluidics of the phacoemulsifier we are using,” he said.

He said the 21-gauge Verges chopper has three irrigation ports, two lateral and one inferior, to ensure a minimum volume of 50 mL/min. It has a ball tip to manipulate tissue and to polish the posterior capsule after aspiration, he said.

Surgical Specialties

Surgical Specialties Corp. makes the Sharpoint disposable knives, which includes its line of Sub-2mm blades.

Dr. Steinert, who uses Sharpoint knives, said the ClearTrap Sub-2mm knives are scored with a line across the blade that indicates the internal depth of the incision.

“You advance the blade up to where this line is, but the blade itself goes further than that and makes a more accurate incision,” he said.

Other knives from Surgical Specialties that are appropriate for MICS include the Clear Corneal designs for between 1.3-mm and 1.6-mm maximum widths and the Sharpoint ClearPort paracentesis series, with widths of 0.6 mm, 0.8 mm and 1.1 mm, according to the company.

More information

Other companies that make instrumentation appropriate for MICS include Eagle Laboratories, Oasis Medical and Stephens Instruments. Eagle Laboratories makes microsurgical blades and knives. Oasis Medical makes a MICS knife with a six-sided blade, according to the company Web site. Stephens Instruments has a large line of scissors and forceps for MICS, according to the company. Ocular Surgery News was unable to reach these companies for more information on their products for the writing of this article. We regret the omission.

Please see more information on the products available for MICS from these and other companies in the Guide to Hand-Held Cataract Instrumentation in the print edition. Included in the guide is contact information for all companies discussed in this article.

For Your Information:

• I. Howard Fine, MD, and Mark Packer, MD, can be reached at 1550 Oak St, Suite 5, Eugene, OR 97401; 541-687-2110; fax: 541-484-3883; e-mail: hfine@finemd.com; mpacker@finemd.com. Dr. Fine has designed instruments for Rhein Medical, MST, Mastel and Katena. Dr. Packer has designed instruments for ASICO.
• Amar Agarwal, MD, can be reached at 19 Cathedral Rd, Chennai 600-086, India; 91-44-2811-6233; fax: 91-44-2811-5871; e-mail: dragarwal@vsnl.com. Dr. Agarwal has designed instruments for MST, HUCO and Geuder.
• Felipe Vejarano, MD, can be reached at Carrera 3 # 5-54, Popayán Colombia; 57-2-824-0242/ 57-3-1557-80082; fax: 57-2-824-1926 (ext. 116). Dr. Vejarano has designed instruments for Accutome.
• Jorge L. Alió, MD, PhD, can be reached at Avda, Denia 111, 0130515 Alicante, Spain; 34-965-150-024; fax: 34-965-151-501; e-mail: jlalo@oftalio.com. Dr. .Alió has designed instruments for Katena.
• David F. Chang, MD, can be reached at 762 Altos Oaks Dr, Ste 1, Los Altos, CA 94024; 650-948-9123; fax: 650-948-0563; e-mail: dceye@earthlink.net. Dr. Chang has designed instruments for Katena and MST.
• Roger F. Steinert, MD, can be reached at 50 Staniford St, Suite 600, Boston, MA 02114; 617-367-4800; fax: 617-573-4912; e-mail: rfsteinert@eyeboston.com. Dr. Steinert has no direct financial interest in any products mentioned in this article, nor is he a paid consultant for any companies mentioned.
• L. Andrew Watkins, MD, can be reached at 427 W 20th St, Ste 100, Houston, TX 77008; 713-862-6631; fax: 713-861-1410; e-mail: watkins@HeightsEyeCenter.com. Ocular Surgery News was unable to confirm whether Dr. Watkins has a direct financial interest in any products mentioned in this article or is a paid consultant for any companies mentioned.
• Rosa Braga-Mele, MD, can be reached at 200 Danforth Ave, Suite 200, Toronto, Ontario, Canada M4K1N2; 416-462-0393; fax: 416-462-3612; e-mail: rbragamele@rogers.com. Dr. Braga-Mele is a paid consultant for Bausch & Lomb. She has no direct financial interest in any products mentioned in this article.