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Refractive Surgery | Sep 2010

Cataract Surgery With the LensAR Femtosecond Laser Platform

The most exciting part of femtosecond cataract surgery is not what we see today, but rather what is on the horizon.

As an innovator in the area of cataract extraction since the late 1980s, I have been involved in the development of phaco technology for many years. Because of my experience, I was asked to become an advisor to LensAR, Inc. (Winter Park, Florida), as the company began testing its femtosecond laser technology for cataract surgery.

About 6 months ago, I traveled to Mexico City to perform 14 surgeries with the LensAR, Inc., platform as part of a clinical trial. While there, my colleagues and I experimented with parameters such as algorithms for softening the nucleus, and we sought to determine the appropriate amount of pressure for docking the laser. In the clinical trial, the procedure progressed differently from how it will when the platform is commercially available; we nevertheless found the laser to be amazing. The eyes we treated had everything from soft to hard nuclei, and in each, we performed a capsulorrhexis and were able to soften the nucleus.

COMPONENTS OF THE INTEGRATED DESIGN
The LensAR, Inc., platform employs unique 3-D confocal-structured illumination imaging in its integrated design; the scanning and measuring system uses the Scheimpflug principle but differs from other imaging techniques, such as optical coherence tomography, in that the object plane, lens plane, and image plane are not parallel to each other but intersect in a common straight line. The advantage is a much wider depth of focus. The laser docks to the cornea using much less pressure than the IntraLase FS laser (Abbott Medical Optics Inc., Santa Ana, California), which is a plus for elderly patients. With information obtained from the laser's anterior segment visualization system, we were able to set the device for the desired depth and width of treatment. The platform allowed us to cut the lens fibrils in any pattern. Because the optimal size and shape for removal of nuclear particulates is unknown, we experimented with cubes and spheres of different sizes.

It is hoped that the femtosecond laser will dramatically reduce the need for phaco energy for the removal of most nuclei. I envision that most soft to moderately dense cataracts will be treated with the laser platform and aspirated using a 0.5-mm I/A or phaco and I/A tip. In this scenario, the phaco machine would be used to augment aspiration of the lens material. For hard cataracts, phaco energy will still be necessary.

Although phacoemulsification is a wonderful and safe procedure, any time the surgeon can avoid having an ultrasonic probe in the anterior chamber, he is eliminating its potentially adverse effects on the blood-aqueous barrier, endothelium, and trabecular mesh-work. Without the use of ultrasound during cataract extraction, the eye's environment is safer, and there is no risk of tearing the posterior capsule with a phaco tip. Femtosecond laser cataract surgery will also be associated with less unexpected vitreous loss and reduced damage to the iris from high-powered interfaces.

QUALITY OF THE CAPSULORRHEXES
Surgeons are getting better at creating quality capsulorrhexes. The LensAR Laser System allows the ophthalmologist to better control the location of the capsulorrhexis as well. A multifocal IOL, for example, should be centered on the visual axis, which is difficult to find during surgery. The femtosecond laser allows the surgeon to identify and create the capsulorrhexis around the visual axis. When the implant is centered in the capsulorrhexis, it will therefore also be centered on the visual axis. The size of the capsulorrhexis is important for successful cataract extraction. The capsulorrhexis must overlap the IOL by 0.25 mm, which can be achieved perfectly in every case with the laser.

Other advantages of femtosecond cataract surgery are that patients love the idea of lasers, and femtosecond cataract surgery has applicability for all ophthalmologists. All cataract surgeons will benefit from improved procedural reproducibility, better capsulorrhexes, easier removal of nuclei, and decreased surgical times. Highvolume surgeons will be able to perform many tasks simultaneously with the LensAR, Inc., platform; they will be able to swing the laser into place for the several steps of the cataract procedure and then move it out of the way so that they may remove the cataract. In this setting, I envision phacoemulsification taking on a new role, and surgeons may start to think of the cataract procedure as a femto-phaco procedure.

THE PROCEDURE OF THE FUTURE
I believe femtosecond laser cataract surgery has real potential. My vision is that a physician will sit down to perform cataract surgery, the patient will be brought into the room, and the femtosecond laser will be put into position. Before it is docked, the laser will perform corneal topography and wavefront analysis. It will find the visual axis and place registration marks. Then, the surgeon will program the refractive goal into the system. The laser will analyze this input and determine an algorithm for the nuclear treatment. It will then perform a demolition by cutting the nucleus into the sizes and shapes selected. Next, it can make the capsulorrhexis around the visual axis, create limbal relaxing incisions for the treatment of preexisting astigmatism, and perform a paracentesis wherever the surgeon desires. The LensAR Laser System can even make a locking incision that is guaranteed to be watertight as well as correct the induced cylinder.

William J. Fishkind, MD, is the Co-Director of Fishkind and Bakewell Eye Care and Surgery Center, Tucson, Arizona, and a Clinical Professor of Ophthalmology at the University of Utah, Salt Lake City. He states that he is a consultant to LensAR, Inc. Dr. Fishkind may be reached at tel: +1 520 293 6740; e-mail: wfishkind@earthlink.net.

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