Get Adobe Flash player
Anterior Segment Section sub Section Heading Cataract Cataract Surgery and the LenSx ® Femtosecond Laser System Richard Potvin, MASc, OD 1 and Sarah Makari, OD 2 1. President; 2. Research Associate, Science in Vision, Burleson, Texas, US Abstract The use of femtosecond laser systems in cataract surgery has been stated to be arguably the single biggest change to the procedure since phacoemulsification. The combination of a controllable high-frequency laser with increasingly advanced ocular imaging technology provides for a surgical precision that is difficult or impossible to duplicate manually. As a new technology, much clinical research is underway to identify best practices, and quantify the benefits of femtosecond cataract surgery. The main measures of interest are improvements in surgical precision, reduced complication rates and lower variability in clinical outcomes compared with manual procedures. The lower variability in outcomes would translate to a higher percentage of patients achieving their desired refractive target after surgery. This article provides an overview of the LenSx® femtosecond laser system, some of the ways in which it is being utilized in cataract surgery, and related surgical/ clinical results recently reported in the peer-reviewed literature. Keywords Femtosecond laser, cataract surgery, capsulorhexis, aberrations, IOL position, lens fragmentation, LRI, incision Disclosure: Richard Potvin, MASc, OD, is a consultant to Alcon. Sarah Makari, OD, has no conflicts of interest to declare. Received: June 16, 2013 Accepted: July 1, 2013 Citation: US Ophthalmic Review, 2013;6(2):89–93 Correspondence: Rick Potvin, MASc, OD, President, SiV Consulting, LLC, 13860 E, Riviera Dr, Berleson, Texas, 76028, US. E: Support: The publication of this article was supported by Alcon. The views and opinions expressed are those of the authors and not necessarily those of Alcon. Femtosecond lasers have been successfully used in ophthalmology since 2001, 1 most notably in bladeless laser-assisted in situ keratomileusis (LASIK). The high frequency of this laser allows for significantly lower energy to achieve a desired effect; this reduces the potential for collateral tissue damage. 2 With modern imaging systems, the laser can be focused to create precise incisions that can be positioned in any desired plane. 3 The success of the technology has resulted in the introduction of femtosecond laser systems into cataract surgery, allowing for automation of some of the most critical steps in cataract surgery. The first available laser system approved by the US Food and Drug Administration (FDA) for this application was the LenSx® femtosecond laser system (LenSx Lasers Inc., Aliso Viejo, California) (see Figure 1). The FDA initially approved the system for anterior capsulotomies and corneal incisions (August 2009) then added approval for lens fragmentation (April 2010). 1 A search of the peer-reviewed literature indicates that it is the most-studied cataract laser to date. System Overview The LenSx femtosecond laser system uses an integrated Fourier-domain optical coherence tomography (OCT) imaging system. 2,4–6 The OCT is used to plan the treatment based on measurements of the cornea, anterior and posterior lens capsule, and crystalline lens nucleus. 5 The standard procedure sequence is capsulotomy, followed by lens fragmentation, then primary and secondary corneal incisions, and finally arcuate keratotomy or arcuate © To u ch MEdical ME d ia 2013 incisions if desired. 1,2,7 Modifications to the procedure sequence can be made to accommodate different requirements: successful laser capsulotomy, lens fragmentation, and corneal incisions postpenetrating keratoplasty, and trabeculectomy have been reported. 8 The preliminary docking procedure and the various steps above are described in detail in the following sections. Docking Mechanism An ideal docking mechanism limits eye movements and corneal folds to ensure appropriate eye stability and efficient supply of laser energy. 9 This must be achieved while minimizing trauma to the eye and limiting intraocular pressure (IOP) rise, to reduce the potential for postsurgical complications. 9 The latest version of the LenSx system uses a proprietary SoftFit™ interface: a 13 mm single piece curved contact lens and suction system to applanate the cornea. 4,7,10–12 This interface is sterile, disposable, and mounted onto the objective (see Figure 2). 1 The force applied by the objective is controlled by a spring-loaded objective lens. 1 When the surgeon observes proper applanation as determined through the live video image, suction is applied. 1 Suction is lower than in previous iterations of the interface, with an average IOP rise of about 16 mm Hg. It is important that a docking system be effective and reliable, to reduce the number of docking attempts and the number of ‘suction breaks,’ which would require additional manipulation of the eye to rectify. Technologic 89