Perfecting art of cataract surgery with guidance technologies

Take-home: Cataract surgery technology continues to advance with improvements that enhance surgical performance every step of the way.

Reviewed by Robert J. Weinstock, MD 

Largo, FL––No matter how advanced a technology becomes, nothing is perfect. The same holds true for cataract surgery technology. There are other complementary tools for femtosecond lasers that are available, which will help surgeons achieve better outcomes for their patients.

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Femtosecond laser cataract surgery has successfully furthered the subspecialty, most notably because it is safer and a more precise method than the manual procedures with the use of arcuate incisions, creation of capsulotomies, and nuclear disassembly.

The missing links

Despite the advancements, there are some technologies are beginning to hot the market, according to Robert Weinstock, MD, who is in private practice in Largo, FL. He pointed to automation, integration, and surgical guidance to help with the throughput of cataract surgery, surgical planning, and the execution of refractive targeting and refractive outcomes.

“We need more surgical planning software that is associated with the lasers to help in the choice of intraocular lenses (IOLs) and the surgical plan for cataract removal and astigmatism treatment and to help free patients from spectacle dependence,” Dr. Weinstock said.

Another area is iris registration. The software for creation of arcuate incisions is becoming available. Software should also customize the laser treatments depending on the density of the lens and the size of the cataract. Surgical field navigation and guidance would provide on-screen navigation to help guide maneuvers, Dr. Weinstock explained.

“We currently are moving toward a surgical navigation concept to use guidance for placing the incisions, capsulotomies, and limbal-relaxing incisions and for selecting toric IOL powers and positioning of the lenses, and IOL centration,” he pointed out. “These are all critical parts of cataract surgery that need to be worked on.”

New technologies that are now incorporated into the lasers include automated registration and treatment plans, cataract grading, and customized fragmentation patterns. Advances introduced into phacoemulsification include surgical cockpit setups with information projected through ocular microscopes or on a three-dimensional guidance screen, all of which, Dr. Weinstock said, will help surgeons perform better surgeries.

The postoperative regimen also will benefit from advancing technologies that provide automated refraction, imaging, and feedback into planning software that drives the nomograms and improves outcomes, he noted.

Some advancements

The LENSAR laser provides streamline iris registration for placing limbal-relaxing incisions and intrastromal marks. Dr. Weinstock explained how the laser uses an image of the undilated pupil and an image of the unwound iris for iris registration. The two images are lined up during the laser treatment and a shift is done to move the arcuate incisions to account for cyclotorsion and head tilt.

The laser can image the nucleus and do automatic nuclear grading and density, based on Scheimpflug imaging, to guide various treatments and the sizes of the laser treatments. After the nuclear imaging, the iris registration occurs and the laser treatment is applied accordingly.

The technologic advances are invaluable. In one such case, Dr. Weinstock described, there was 17º error in cyclorotation.  “In patients with larger degrees of astigmatism, if the cyclorotation error and head tilt are not considered, the limbal-relaxing incisions will be placed incorrectly,” he said. “This software is desperately needed to improve our outcomes with limbal-relaxing incision.”

Programmable pattern selection software, also in the LENSAR laser, describes the grade and density of the cataract. “The surgeon can program the laser to perform a simple fragmentation pattern for a soft lens or a more robust matrix or cube pattern for a denser cataract. This can be automated by the laser rather than being decided manually,” he said.

The Verion Image Guided System with the LenSx laser (Alcon Laboratories) has features that are similar to those of the LENSAR laser. The features of the system include a preoperative diagnostic device that obtains an infrared image, a planning software station, the laser, and intraoperative guidance. The images obtained show the position of the capsulotomy, the optimal position for a multifocal optic, and a toric IOL.

Intraoperative aberrometry

The ORA (Alcon Laboratories) and Holos IntraOp (Clarity Medical Systems) are the two units that are commercially available.

The ORA, which is familiar to most surgeons as part of the Verion system, is excellent for determining aphakic power selections for monofocal, presbyopic-correcting, and toric IOLs, Dr. Weinstock said. It performs a pseudophakic measurement and advises the surgeon when the IOL is in the correct position and axis.

Dr. Weinstock added that the ORA provides improved refractive outcomes in well-documented published studies.

The newly released Holos IntraOp is similar to the ORA and provides similar measurements. Studies are currently under way to evaluate the performance of the instrument compared to ORA. “I am sure it will achieve the same goals for our patients,” Dr. Weinstock said.

The Callisto (Carl Zeiss Meditec) and the TrueVision 3D Surgical system (TrueVision Systems) are two other devices used to facilitate intraoperative surgery. Dr. Weinstock commented that the resolution of the screen and camera of the TrueVision are so advanced that the microscope oculars are unnecessary.

“The surgeon can sit in a comfortable position, wear 3D glasses, look at the screen, and operate directly off of it,” Dr. Weinstock said. “I operate heads up off a screen on all cataract surgeries without looking through a microscope. This is the future of cataract surgery.”

A surgical cockpit setup allows the integration of other platforms to visualize, for example, ORA on one side of the screen and the eye on the other side. This allows the surgeon to see all needed information on one screen rather than looking away at another separate screen.

Other systems

Bausch + Lomb is developing the Spectrus unit, which is another intraoperative guidance system that is similar to the Callisto.

“Cataract surgery continues to evolve,” Dr. Weinstock concluded. “The femtosecond laser is not the only component of interest regarding the outcomes. All of these devices are helping to achieve better outcomes for our patients. All technologies must continue to be safety-and-outcome driven.

“Automation with lasers and guidance is the future of cataract surgery. The devices need to be integrated so that the procedure is more seamless and there is better throughput in the operating room. However, attention must be paid to efficiency, economy of scale, and cost effectiveness,” he added.

Robert J. Weinstock, MD

e. rjweinstock@yahoo.com

Dr. Weinstock is a consultant for Bausch + Lomb, Alcon Laboratories, and LENSAR. He receives honoraria from Alcon Laboratories and Bausch + Lomb; and has ownership interest in TrueVision.