Upgrades, integration enhance cataract surgery femtosecond laser

July 1, 2014

Leading cataract surgeons speak to recent enhancements to a femtosecond laser and benefits of its integration with an image-guided system.

 

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Leading cataract surgeons speak to recent enhancements to a femtosecond laser and benefits of its integration with an image-guided system.

Dr. Slade

 

By Cheryl Guttman Krader; Reviewed by Stephen Lane, MD, and Stephen G. Slade, MD

Femtosecond laser-assisted cataract surgery technology allows ophthalmic surgeons to perform surgery with increased reproducibility and percision-and ultimately leads to better patient outcomes.

 

Through continuous innovation that includes several hardware and software upgrades, one femtosecond laser platform (LenSx Laser, Alcon Laboratories) now includes an image-guided system (Verion) and is part of a multicomponent, integrated surgical system (Alcon Cataract Refractive Suite) that augments the performance of the laser and delivers better surgical results. Two cataract surgeons familiar with the platform share their insights on the evolution of this technology.

 

 

 

Patient interface enhancement

 

In 2013, a new patient interface (SoftFit) was introduced for the femtosecond laser that has improved its performance and made its use more surgeon- and patient-friendly. The new patient interface is a single-piece system, featuring a hydrogel contact lens that is placed within the applanation cone. It brings easier docking, reduces IOP elevation while the eye is docked, affords increased patient comfort, and results in much more consistent creation of complete (free-floating) capsulotomies.

“The presence of a high-water-content hydrogel contact lens between the eye and interface of the laser minimizes corneal compression to reduce microfolds in the cornea that could interfere with laser energy delivery and lead to skip areas in the capsulotomy,” said Stephen S. Lane, MD, medical director, Associated Eye Care, Twin Cities metropolitan area, Minnesota, and adjunct clinical professor of ophthalmology, University of Minnesota, Minneapolis.

 

 

 

The new patient interface helps to ensure that the capsule cut is made fully around the entire 360° circumference, according to Dr. Lane.

“Then, the resulting smooth-edged, free-floating remnant eliminates the risk for tears into the periphery, and can be removed from the anterior chamber very easily,” Dr. Lane explained.

By applying suction, the patient interface still assures the eye is held stable during the femtosecond laser procedure, but IOP increases by no more than about 16 mm Hg from its baseline, which makes it a safer and more comfortable experience for patients.

Stephen G. Slade, MD, in private practice, Houston, noted that the femtosecond laser patient interface already had “best in class size,” being the smallest patient interface on the market.

“It is exceptionally rare that we cannot fit the [patient interface] to a patient,” Dr. Slade said. “I have only seen it once in several thousand cases.”

 

 

Evolution in phacofragmentation

 

Another significant enhancement to the femtosecond laser is the new matrix lens fragmentation pattern that cuts the lens into a series of cubes or “French fries” using a crisscross/grid-type pattern. With this option, surgeons can individualize their approach, varying the number of units into which the lens is cut, taking into account the characteristics of each lens and their desired surgical technique.

Dr. Lane“With the original fragmentation software, the lens could be cut into cylinders or into 4 to 8 pie-shaped pieces with radial incisions,” Dr. Lane explained. “The matrix pattern can create many more cleavage lines that gives the surgeon much more flexibility in choosing where to break up the lens, and by dividing the lens into many more fragments, seems to allow for much more efficient lens removal with reduced need for ultrasound energy.

“Lens fragmentation using the matrix pattern also takes less time than the cylinder or linear cuts, which adds to increased patient comfort,” he added.

Although not new, another benefit of the femtosecond laser is its proprietary variable numerical aperture technology.

This feature adjusts the focus angle of the laser beam so that energy delivery is optimized for its target structure and intended purpose, whether that be to create the main or sideport corneal incisions, arcuate corneal incisions for astigmatic correction, anterior capsulotomy, or lens fragmentation.

For example, due to the curvature of the corneal surface, the angulation of the beam needed to create an astigmatic incision that is tangential to the surface and to the proper depth differs from the angulation that will assure an anterior capsulotomy with clean-cut edges or that is needed to cut through the lens, Dr. Lane explained.

“A laser used for corneal surgery where the target tissue in only 500 µm thick and accuracy should be within microns is a very different design from a cataract surgical laser treating a target that is millimeters deep and only needing accuracy within tens of microns,” Dr. Slade said.

 

 

 

 

 

Potential with image-guided system

 

Combining the laser with the new image-guided system offers further advantages. The system incorporates digital planning and surgical positioning tools that are specifically designed for seamless integration with the femtosecond laser and other current and future surgical technologies with the goal of delivering improved surgical outcomes.

The image-guided system is used in preoperative planning for obtaining keratometry and pupil measurements.

In addition, it captures a high-resolution digital image, creating a “fingerprint” detailing anatomical landmarks that are used for intraoperative registration to guide accurate placement of corneal incisions and IOL alignment.

The system also performs IOL calculations, and helps the surgeon create a surgical plan for the correction of astigmatism with toric IOLs, astigmatic incisions, or a combination of the two.

“The reference image is exported to the [laser] where it assures precision in the location of the primary, secondary, and arcuate incisions,” Dr. Lane said. “The software maps and matches [registers] the landmarks of the eye as it appears under the laser to the preoperative reference image to provide a level of accuracy that is simply not achievable when making incisions manually with handheld markers and ink marks as a guide.”

 

 

Dr. Slade noted that the image-guided system has tremendous potential for the future.

“We now have a system where our diagnostics talk to our treating devices and vice versa,” he said. “This can create feedback loops for treatments based on past phaco parameters, better IOL estimations, and expanded uses for the [laser].”

The image-guided system is also an asset for surgeons who are not using the laser because the tracking overlay that is generated using the reference image is also transferred to the operating microscope. This overlay-which appears in the microscope oculars and as a heads-up display-provides a powerfully accurate, real-time template for guiding corneal incisions, capsulorhexis creation, and IOL alignment.

The image-guided system also performs IOL calculations, using the data from the preoperative diagnostic evaluation and robust formulas.

Because data obtained from the reference unit is wirelessly exported to the IOL planner, the possibility of transcription errors due to manual entry is eliminated.

Together with an ophthalmic microscope (LuxOR LX3 with Q-VUE, Alcon) and a phacoemulsification platform (Centurion Vision System, Alcon), the femtosecond laser platform and the image-guided system form the Cataract Refractive Suite, which, as an entire integrated platform, allows surgeons to plan and perform cataract refractive procedures with far greater precision than has been possible in the past.

“Each of these components works synergistically with the others to improve outcomes, but benefit can also be derived from using each one individually,” Dr. Lane said.

He explained this concept using the following analogy, “When I was in college and wanted to have a great stereo system, I could only afford to buy a single piece of equipment at a time. But starting with just a new tuner gave me better sound, and then I built on by replacing the other components when I was able.

“Similarly, outcomes are improved by each component of the Cataract Refractive Suite, but each addition progressively brings us toward our goal of hitting our refractive targets, thereby achieving excellent results with greater consistency for our patients, especially those who choose an advanced technology IOL,” he said. 

 

 

 

 

 

Stephen Lane, MD

E: sslane@associatedeyecare.com

Dr. Lane is a consultant to Abbott Medical Optics, Alcon Laboratories, Bausch + Lomb, and WaveTec Vision.

 

Stephen G. Slade, MD

E: sgs@visiontexas.com

Dr. Slade is a consultant to Alcon Laboratories.