March 2009

 

COVER FEATURE

 

Cataract surgery innovations

Chop techniques guided by technological innovations


by David Laber EyeWorld Staff Writer

   

As instruments and machines have evolved, so too have the methods for which surgeons use to break apart the routine and most challenging cataracts

Instruments and phacoemulsification chopping methods have been in the forefront of cataract surgery, and a plethora of books, videos, and courses are available to bring surgeons up to speed on the latest tools and how they are used to improve phaco.

Never is the magnitude of materials more prevalent than during the annual meetings hosted by ASCRS and the American Academy of Ophthalmology (AAO), respectively. At these meetings, all three—books, courses, and videos—are available at one place for surgeons.

Adapting techniques to the tools

Barry S. Seibel, M.D., clinical assistant professor, Jules Stein Eye Institute, University of California, Los Angeles, is among the leaders in phaco chop education. In 2008, Dr. Seibel published the fourth edition of his book, Phacodynamics, which focuses on customizing cataract surgery for each patient. Dr. Seibel also is a panel member for David F. Chang’s, M.D., semi-annual cataract course, Learning Phaco Chop: Pearls and Pitfalls. Dr. Chang, clinical professor, University of California, San Francisco, leads this course at both the ASCRS and AAO annual meetings every year.

Dr. Seibel credits some of the handheld instruments for advancing the chop maneuvers. For example, the original horizontal and vertical chop methods employed instrumentation that was “off-putting to a good deal of doctors who might have attempted it.”

The horizontal choppers were bulky, and the original vertical choppers had a sharp tip that was a safety concern. Dr. Seibel has designed both horizontal and vertical choppers to address these concerns.

For example, the Seibel Horizontal Safety Chopper (Rhein Medical, Tampa, Fla.) has a ball tip at the end to maximize the surface area and help prevent posterior capsule rupture in case there is contact with the capsule. It also has a radial shaft as opposed to sharp right angle bend, which facilitates easier entry and exit of the eye.

His vertical chopper has a flat profile with a rounded edge to it to minimize potential pressure were the chopper to come in contact with the capsule. Other manufacturers and designers also have modified tools available.

“I think these evolutions of instruments have sought to address these initial concerns with the original instrumentation, and I believe that has helped to foster more acceptance of chopping maneuvers in general,” Dr. Seibel said.

But the new instrumentation goes further than just making the procedures more accessible, he said. The instruments have caused “little evolutions” to the chop techniques along the way as well.

Dr. Seibel points out that the vertical chop method carries various different titles that reflect subtle adaptations to the technique including the snap-and-split, quick-chop and phaco-crack techniques.

“Essentially they are the same maneuver, but with little, subtle variations on it have been employed by various doctors,” Dr. Seibel said. To which he also noted that another one of Dr. Chang’s contributions has been to organize the techniques into categories of horizontal and vertical techniques.

Phaco machines also adapting

Handheld tools are not the only devices making a splash in phaco technology. When higher vacuum settings are used on hard cataracts, there is more potential for a post-occlusion surge and anterior instability. Dr. Seibel said the dual linear pedal control in machines such as the Millennium Microsurgical System and Stellaris Vision Enhancement System (both from Bausch & Lomb Surgical, San Dimas, Calif.) helps address these potential problems.

The Whitestar Signature System (Advanced Medical Optics, AMO, Santa Ana, Calif.) also includes two pedal options: a traditional, fully programmable, single linear foot pedal and a wireless, fully programmable, dual linear capable foot pedal.

The key advantage of the dual pedals is that it allows simultaneous and independent linear control of fluidics and ultrasound. With standard models, it is virtually impossible to achieve modest levels of ultrasound and vacuum simultaneously, and these settings are desirable for carouseling phaco aspiration of chop fragment, he said. When dealing with brunescent nuclei, by definition, the surgeon is likely to use higher phaco energy than with a softer nucleus, so they need to be all the more cognizant of the potential for incisional burns. They need to employ such cautions as using hyper pulse power modulations, consider nontorsional energy and being cognizant of the fluidics in the eye such that an adequate fluid turnover is produced in the eye to help cool the phaco tip.

Ultrachopper attacks hard cataracts

Another new device that is changing techniques, the Ultrachopper, was presented by Luis J. Escaf, M.D., Clinica Oftalmologica del Caribe, Barranquilla, Columbia, in 2007. At the 2008 ASCRS annual meeting, Dr. Escaf’s film, Ultrachopper: New Era in Cataract Surgery displayed the device and showed it in action. (Editors’ note: Dr. Escaf and the manufacturer have a confidentiality agreement.) The Ultrachopper’s phaco needle is flattened on its tip, angulated with a downward bend thinner in the interior portion and internally hollowed with two aspiration ports placed laterally. The needle is attached to the phaco hand piece, which allows it to generate ultrasonic vibrations in position three of the foot pedal behaving like a true ultrasonic knife.

The most difficult aspect in hard cataracts is to retrieve the fragments, which is made easier with the Ultrachopper. The device can be used in bimanual phaco as well.

With a standard phaco machine, the surgeon has coaxial movement, but when connected to the Ozil (Alcon, Fort Worth, Texas) handpiece, it has lateral motion allowing simultaneous cuts, and it will separate the cataract material before emulsification. The device does not push on the cataract, so it protects structures like the zonules.

In a 2007 issue of Cataract & Refractive Surgery Today Europe, Dr. Escaf described two techniques using the Ultrachopper. Ultraphaco is when the surgeon uses either coaxial phaco or coaxial microphaco to emulsify the cataract fragments after cracking the nucleus with the Ultrachopper. Ultraqual refers to the pairing of the Ultrachopper with Aqualase (Alcon).

Techniques for tough cataracts

With regard to chopping, it helps to de-bulk a dense cataract through doing some initial sculpting in the center of the nucleus, which has been described by several physicians in terms such as crater quick chop. This method optimizes both the ultrasound energy as well as the vacuum in order to achieve a tight grip, Dr. Seibel said.

Two such methods were introduced at the 2008 ASCRS film festival. Roop Sangeeta, M.D., Meerut, India, described his circumferential chop technique in which he sculpts a shallow crater in the center of the nucleus. Then he performs a 360 degree peripheral chop as opposed to creating full-thickness cracks through the center. This step minimizes stress on the capsules and zonules. Then Dr. Sangeeta emulsifies the hard center followed by the thinned-out remaining shell.

Hong Kyun Kim, M.D., Kyungpook National University, Daegu, South Korea, described decrease and conquer. In his technique, after stabilizing the nucleus with the phaco tip, he separates the epinucleus from the endonucleus. After the separation, Dr. Kim said the volume of the nucleus is “decreased” and then he “conquers” the remaining lens.

Dr. Seibel said a lot of surgeons are frustrated if they have an insufficient grip on the cataract when they perform a chop, and the attempt at chopping itself often dislodges the cataract from the phaco needle that was holding it. This problem is often traced to insufficient vacuum or and insufficient vacuum seal at the aspiration port of the phaco needle.

An insufficient vacuum seal often occurs from placing the phaco needle too anteriorly or not deeply enough into the nucleus, Dr. Seibel said. Another example is to use too much of a parameter when establishing the vacuum seal by applying too much ultrasound or vacuum, which then creates a hole in the nucleus that is larger than the phaco needle itself hence failing to create a tight vacuum seal.

Editors’ note: Dr. Seibel has financial interests with Bausch & Lomb (Rochester, N.Y.) and with the choppers he developed for Rhein Medical (Tampa, Fla.). In addition to the previous editors’ note, Dr. Escaf also has financial interests with Alcon (Fort Worth, Texas). Drs. Sangeeta and Kim do not have any financial interests related to their comments.

Contact information

Escaf: +57-5-357-3169, oftalmocaribe.le@gmail.com
Seibel: 310-444-1134, eyedoc202@earthlink.net

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