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Refractive Surgery | Sep 2010

New Generation of Femtosecond Lasers Emerges

Three companies are proposing technologies to perform steps in cataract surgery.

The pursuit of flawless surgical outcomes fuels the persistent evolution of cataract surgery. Beginning with the development of phacoemulsification by Charles D. Kelman, MD, continual advances have delivered better postoperative results. Phaco machine improvements have expanded margins of safety, and newer lens designs have produced superior visual outcomes. These advances may not equate with improved surgical results, however, if the surgical technique itself is compromised.

Arguably the most important and difficult step in cataract surgery, the capsulorrhexis is critical to the safety and efficacy of the procedure.1,2 A good anterior capsulorrhexis is centered and circular, with a clean, undamaged capsular edge. Surgeons use a manual technique with either a bent needle or forceps to create the capsulorrhexis. Now, early results with a new generation of femtosecond lasers for intraocular use show promise for the creation of the anterior capsulotomy, as well as for nuclear fragmentation and incision creation. Many questions require answers. Will this generation of femtosecond lasers pave the way for enhanced outcomes in refractive cataract surgery? Will it reduce the risks of adverse events, including endophthalmitis, posterior capsular rupture, endothelial cell loss, zonular dehiscence, macular edema, and retinal detachment?

Femtosecond laser pulses to the anterior capsule and crystalline lens during cataract surgery require different parameters from those used by femtosecond lasers for corneal surgery. Specifically, the newest intraocular femtosecond lasers penetrate deeper into the eye—approximately 7,500 µm versus 1,200 µm for those used to date in corneal surgery.3 Three companies have developed femtosecond laser cataract surgery technology: LensAR, Inc. (Winter Park, Florida); LenSx Lasers, Inc. (Aliso Viejo, California), which Alcon, Inc. (Huenenberg, Switzerland), has recently proposed to acquire, pending US Securities and Exchange Commission (SEC) and other regulatory approvals; and OptiMedica Corp. (Santa Clara, California). These companies are banking on the idea that femtosecond lasers will improve the precision of key surgical steps that will translate into optimal postoperative outcomes. As a testament to the confidence in this procedure, OptiMedica Corp. recently announced its decision to sell the company's glaucoma and retina assets to Topcon Corp. (Tokyo). This definitive agreement allows OptiMedica to focus exclusively on the development and commercialization of cataract surgery technologies, especially its femtosecond platform.

In time, surgeons will be able to evaluate femtosecond cataract technologies and determine if they are worth the investment. Until then, ophthalmologists rely on commentary from the companies and the key opinion leaders who have already tested these technologies. All three companies mentioned herein have unique positions in the current marketplace. This article provides an overview of the three new femtosecond cataract laser systems and recaps previously released and published clinical results.

LENSAR
This platform is now in development for constructing the anterior capsulotomy, fragmenting the nucleus, and creating limbal relaxing and clear corneal incisions (Figures 1 and 2); however, company information alludes to a different initial direction for its femtosecond laser—presbyopic correction. Randy W. Frey, the CEO of LensAR, Inc., licensed a patent and patent application to use the technology for softening the natural crystalline lens to restore accommodation. Studies with a prototype laser quantified a strong safety profile for presbyopic correction and showed that it avoided cataract formation in a sensitive animal model, according to company information.

After some prompting from LensAR, Inc., board member Richard Keates, MD, Mr. Frey decided to turn his attention to cataract surgery. In the first cataract procedures attempted, the laser accomplished perfect capsulotomies and aspiration of lens material sans phaco ultrasound power. Ramon Naranjo Tackman, MD, Director of Corneal Services at APEC Hospital Luis Sanchez in Mexico City, is among the surgeons with clinical experience using the LensAR laser for cataract surgery. According to the company, Dr. Naranjo Tackman has used the laser to cleanly cut cataracts of up to grade 4. After a recent algorithm upgrade, Harvey Uy, MD, of Manilla, Philippines, has laser-fragmented and removed cataracts as hard as grade 5 with significantly reduced ultrasound energy, Mr. Frey told Cataract & Refractive Surgery Today Europe in an e-mail. “The detailed algorithms really matter on the higher grade cataracts,” Mr. Frey said.

The LensAR Laser System offers measurement-guided beam delivery for automated measurements and for cutting ocular anatomy using its proprietary, modified Scheimpflug imaging, 3-D Confocal Structured Illumination (CSI) technology. According to the company, results with this technology were accurate in animal studies and confirmed in human clinical studies. The company continues to research LensAR's applications for cataract surgery.

In May 2010, following the release of clincal data from the APEC Hospital Mexico City that showed more precise diameters and circularities of capsulotomies with the femtosecond laser versus manual capsulorrhexis, the LensAR Laser System received 510(k) clearance for performing anterior capsulotomy during cataract surgery. This is the first FDAcleared indication for LensAR; however, Mr. Frey told CRST Europe that the company will seek approval for performing cataract (clear corneal) and limbal relaxing (astigmatic) incisions as well. Upon FDA approval, a software upgrade will be available for presbyopic algorithms. See Cataract Surgery With the LensAR Femtosecond Laser Platform for a surgeon's perspective on this platform.

LENSX
Ronald Kurtz, MD; Tibor Juhasz, PhD; and Eric Weinberg are the cofounders of LenSx Lasers, Inc. Perhaps the biggest news for this trio is the company's recent proposed acquisition by Alcon, Inc. In a deal worth up to $744 million, Alcon will reportedly pay $361.5 million in cash, plus a contingent payment of $382.5 million based upon the achievement and overachievement of future femtosecond unit and procedure fee revenue milestones, pending the necessary US regulatory approvals. Image-guided clinical applications of the LenSx laser include liquefying or fragmenting the lens; forming the anterior capsulotomy; and creating all corneal incisions (Figures 3 and 4). Company literature explains that integration of proprietary optical coherence tomography (OCT) allows precise localization of surgical laser pulses.

Zoltan Nagy, MD, Clinical Professor at Semmelweis University in Budapest, Hungary, was the first to use the LenSx technology clinically.4,5 In his study, the laser was used for anterior capsulotomy in 60 cases; all capsulotomies had smooth, uniform edges, and there were no capsular tears or adverse events. Dr. Nagy compared results with those for 60 control individuals in whom manual capsulotomy was performed. The diameter of the capsulotomies created with the LenSx was significantly more reproducible. Dr. Nagy reported that the diameter of the capsulorrhexis was individualized for each treatment, with the diameter of his typical capsulotomy ranging from 4.5 to 5 mm for a 6-mm optic IOL. According to ex vivo testing and scanning electron microscopy in animal models, similar smoothness and mechanical strength of the capsulotomies were seen with the femtosecond laser and manual capsulotomy.

The LenSx Laser has also received FDA clearance for lens fragmentation, or laser phacofragmentation, during cataract surgery. In Dr. Nagy's initial series, softer lenses were successfully fragmented into small pieces that were removed with I/A and required no phacoemulsification. Harder lenses were successfully fragmented into quadrants for more efficient removal with low phaco power and energy. He reported no complications and, in an article published last year in CRSToday Europe, said that the technology “eliminates the need for manually creating grooves with the phacoemulsification handpiece.”6 Less total ultrasound power was used compared with other phaco techniques. LenSx has established a second clinical site in Houston, where Stephen Slade, MD, performed the first femtosecond laser cataract surgery procedures in the United States in February.

The LenSx Laser is currently the only femtosecond laser to receive 510(k) clearance from the FDA for the creation of corneal incisions. It also has clearance for anterior capsulotomy and phacofragmentation. See Real-Time Imaging With the LenSx Femtosecond Platform for Cataract Surgery for a surgeon's perspective on the LenSx platform.

OPTIMEDICA
With an outstanding reputation in the field of retinal surgery and retinal lasers, OptiMedica Corp. has also invested considerable time and funding into the arena of cataract surgery. Behind the scenes, the company worked to develop a noninvasive, intraocular femtosecond technique for some of the most technique-driven steps of cataract surgery. Company literature reports that this laser is capable of creating precise corneal incisions and capsulotomies and of fragmenting the lens (Figures 5 through 7). Safety studies are complete, and ongoing clinical trials reportedly showing promising results. According to the company, its femtosecond laser is en route to providing significant benefits to both surgeons performing and patients undergoing cataract and refractive lens surgery.

“With the OptiMedica laser cataract system, I have successfully and easily performed anterior capsulotomies, fragmented the lens, and created cataract incisions and corneal relaxing incisions,” William W. Culbertson, MD, of Miami, wrote in an article published recently in CRST Europe's sister publication, CRSToday.7 “The OptiMedica platform was designed to enable the highest level of surgical precision, surgical control, and patient safety during cataract surgery.”

Ongoing trials will provide optimized treatment algorithms, according to company literature. Dr. Culbertson and other ophthalmologists have collaborated with OptiMedica's physicists and engineers to tailor the laser platform to the specific needs of the cataract surgery procedure. “Of the many parts of the system that we have tested, iterated, and refined, two have a particularly significant impact on precision and clinical performance: the patient interface and the integrated imaging system,” Dr. Culbertson wrote in CRST. “This novel interface provides a wide field of view for visualizing the limbus and centering and placing incisions, [and] the integrated imaging system ensures the safe delivery of laser energy and guides my treatment— most importantly, with system-calculated options for centering my capsulotomy.”

Dr. Culbertson and colleagues Juan Battle, MD, and Rafael Feliz, MD, conducted a study comparing excised tissue from manually torn capsulorrhexes with tissue from laser capsulotomies. Their early results suggest that laser capsulotomies with the OptiMedica platform are an order of magnitude more circular and within 100 μm of the intended diameter.

In an interview with CRST Europe, Julian D. Stevens, MRCP, FCRS, FRCOphth, of Moorfields Eye Hospital, London, said that femtosecond-assisted lens extraction with the OptiMedica platform is a new paradigm in lens surgery.

“The change is as significant as phacoemulsification smallincision surgery was to extracapsular cataract surgery,” he said. “Combining a femtosecond laser with real-time OCT guidance creates an entirely new procedure. We are only at the dawn of what the system is capable of achieving; semiautomation and then automation of each step of the procedure will surely occur. The OptiMedica system enables radical and innovative changes.”

A cataract surgical video featuring OptiMedica Corp.'s femtosecond laser was first shown at the 2009 ESCRS Annual Meeting in Barcelona, Spain, and most recently at the World Ophthalmology Congress (WOC) in Berlin in June 2010. The technology uses real-time intraoperative OCT visualization in the anterior chamber and on the cornea to determine the relevant dimensions and thicknesses of the lens and cornea and to guide treatment.

See Femtosecond Cataract Surgery With the OptiMedica Platform for a surgeon's perspective on the OptiMedica Corp.'s femtosecond platform.

DIFFERENTIATION OF PLATFORMS
How the three companies will differentiate their lasers remains to be seen, John Vukich, MD.

“All three platforms use similar concepts and view the market similarly in terms of the platform's appeal,” he said in an interview with CRST Europe. “It will come down to the delivery of the unit, including such things as: Are the ergonomics consistent with operating room flow? Is it easy to use? Is the interface friendly for the surgeon? Does it provide a rapid turnaround?” Dr. Vukich is a partner at the Davis Duehr Dean Center for Refractive Surgery in Madison, Wisconsin, and is a consultant to and investigator for OptiMedica Corp. He said that to be successful the technology has to be efficient and smooth; and the platform has to be easy to use.

PERFECT TIMING
“It has been a decade or more since there has been real innovation in cataract surgery,” said William J. Link, PhD, in an interview with CRST Europe. “Femtosecond laser technology advanced LASIK nicely, and it provided ideas about how [the technology] could be developed for use in cataract surgery.” Dr. Link is a Founder and Managing Director of Versant Ventures (Menlo Park, California), a leading health care focused venture capital firm specializing in early-stage investments in medical devices, biotechnology/ pharmaceuticals, health care services, and health care information technology.

“I am optimistic that femtosecond technology will penetrate the cataract market substantially,” Dr. Link said. “The initial customers will be surgeons who are implanting premium IOLs for presbyopia as well as performing cataract removal. Experts believe that the femtosecond laser will deliver some services in the cataract procedure that are currently uncovered and could demand premium pricing.”

Although the early adopters will be cataract practices and surgeons already in the premium channel, Dr. Link predicts that, as the technology is refined and used more broadly, it will penetrate into standard cataract procedures.

“Ophthalmic surgeons are wonderful customers for new technology because they are familiar with laser technology,” he said. “This will be a refreshing opportunity for surgeons to use those skills in the cataract procedure. It's a natural fit.”

Regarding the appeal of femtosecond cataract technology to patients, Dr. Link said they have always wanted to believe surgeons were doing laser cataract surgery. There is an “openness,” he said, on the part of consumers that laser surgery is better than traditional surgery.

“This is a natural and important evolution in cataract surgery,” Dr. Link remarked. “This is the way innovation can work, where technology is developed and refined in one application—in this case LASIK— and then it is refocused and redeployed in another application. The timing is perfect for cataract sugery to advance to the next level.”

CONCLUSION
The latent potential of intraocular femtosecond lasers is surfacing, with growing support from the industry to develop this technology for prime-time use. If surgical results with the femtosecond laser continue to improve the precision, reproducibility, and predictability of cataract surgery (including lens fragmentation, the incision's creation, and the capsulorrhexis), it may be wise for ophthalmologists to consider investing in an intraocular femtosecond laser. The next few years will be telling.

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