Innovations facilitate microincision cataract surgery techniques

One surgeon says there is still room for improvement in IOL injection systems.

As microincision cataract surgery becomes more common, advances in instrumentation will facilitate techniques for either bimanual or coaxial microincision procedures.

In any cataract procedure, surgical knives and capsulorrhexis forceps are standard equipment. For microincision cataract surgery (MICS), these instruments are being developed, often by the surgeons themselves, to accommodate the various approaches to making and working through sub-2-mm incisions.

Khiun Tjia, MD, said he believes that IOL injection systems require improvement for the 1.8- to 2-mm incisions used in MICS.

“Ultrasound technology by itself and fluid dynamics actually are ready for smaller surgery,” Dr. Tjia told Ocular Surgery News in a telephone interview.

Capsulorrhexis forceps, diamond knives

Capsulorrhexis forceps may be the most useful instrument for surgeons performing either bimanual or coaxial procedures, according to OSN Cataract Surgery Section Member I. Howard Fine, MD.

“Every surgeon should have a microincision capsulorrhexis forceps,” he told OSN.

The Fine-Hoffman rhexis forceps (MicroSurgical Technology) can be oar-locked in a 1.1-mm incision and manipulated with only finger movement. These forceps have a squeeze handle and a capsulorrhexis portion that can be removed and replaced with suture forceps, tying forceps, iris forceps or different types of scissors for intraoperative manipulation through the microincision, he said.

Little viscoelastic leaks from the microincision during the creation of the capsulorrhexis, so the chamber remains stable, which is particularly important in cases of zonular dialysis when the lens might move as a result of its poor adhesion to the ciliary body, Dr. Fine said.

“In the case of a cataract, when one is afraid of the rhexis tearing, it’s much easier to control because all of the viscoelastic stays in the eye and tamponades the capsule,” he said.

Dr. Fine said he also values the precision that diamond knives allow for incision architecture.

“They give us perfect incisions that are 1.1 mm in width internally and 1.3 mm in width externally,” Dr. Fine said, adding that this slightly funnel-shaped, trapezoidal incision allows manipulation of the instruments without stretching or tearing the incision.

Fluidics

Maintaining anterior chamber stability is key to preventing posterior capsule rupture during MICS, Dr. Tjia said.

The same problems can occur with all small incisions, whether they are bimanual or coaxial, Dr. Tjia said. Downsizing incisions necessitates reduced irrigation flow, which is a potential drawback for MICS.

“The less irrigation flow you have, the less aspiration flow you can have. You can’t take out more than you put in,” he said.

Manufacturers have focused on this area over the last 10 years, and hardware and software improvements have helped regulate surge flow, Dr. Tjia said.

“If you have lower surge flow, the anterior chamber stability is reassured,” he said.

Dr. Tjia said OZil technology (Alcon), which has no intrinsic repulsion at the nonlongitudinal phaco tip, can help the surgeon use lower fluidic settings for every incision size.

“The smaller the incision size, the more advantage you can get from this technology,” he said.

Another innovation in phaco technology that minimizes repulsion at the phaco tip is the Ellips (Advanced Medical Optics) transversal ultrasound handpiece, Dr. Tjia said, which incorporates lateral and longitudinal motions to cut an elliptical path.

These new technologies, which reduce the need for high fluidic settings, “will make microsurgery something very normal and routine,” Dr. Tjia said.

IOLs

Dr. Tjia said that, with the latest technologies, transitioning from coaxial to microcoaxial procedures is an easy change for surgeons. However, the most-used IOLs and injection systems “do not reliably, easily allow surgeons to go below 2.2 mm,” he said.

Since the 1970s, there has been a cycle of smaller phaco incision sizes preceding smaller IOL implantation sizes, Dr. Fine said.

“I’m not aware of any lenses that will go through the 1.1- to 1.3-mm incision that we use for bimanual microincision, but my guess is they will come,” he said.

“In the early ’80s when we were doing phaco and we had to open the incision to 7 mm to implant the flat lenses, people used to say, ‘What’s the point?’ And we used to say, ‘The point is, phaco’s a better way to take a cataract out,’” Dr. Fine said. “Today surgeons are saying ‘What’s the point? You have to open the incision to at least 2.2 mm to put a lens in.’ And we say, ‘The point is it’s a better way to take a cataract out.’”

For more information:

I. Howard Fine, MD, can be reached at Drs. Fine, Hoffman & Packer, LLC, 1550 Oak St., Suite 5, Eugene, OR 97401; 541-687-2110; fax: 541-484-3883; e-mail: hfine@finemd.com. Dr. Fine is a paid consultant for Advanced Medical Optics, and he receives research and travel grants from Alcon. Dr. Fine does work with MicroSurgical Technology to design various instruments and is a member of its medical advisory board, but he does not receive any compensation from the company.

Khiun Tjia, MD, can be reached at Isala Klinieken, Locatie Weezenlanden, Groot Weezenlanden 20, 8011 JW Zwolle, The Netherlands; 31-38-424-2980; fax: 31-38-424-3334; e-mail: k.tjia@isala.nl. Dr. Tjia is a consultant for Alcon.

Advanced Medical Optics can be reached at 1700 E. St. Andrew Place, Santa Ana, CA 92705; 714-247-8200; fax: 714-247-8672; Web site: www.amo-inc.com. Alcon can be reached at 6201 South Freeway, Fort Worth, TX 76134; 817-293-0450; fax: 817-568-6142; Web site: www.alconlabs.com. MicroSurgical Technology can be reached at 8415 154th Ave. NE, Redmond, WA 98052; 888-279-3323; fax: 425-556-0437; Web site: www.microsurgical.com.

Pat Nale is an OSN Staff Writer who covers all aspects of ophthalmology.