Acceptance of FLACS in flux
Femtosecond laser-assisted cataract surgery, or FLACS, has been available to the U.S. cataract surgeon for just under 8 years. In the following commentary, I will mix some facts with some opinions and clinical impressions, which is what every surgeon finds themselves doing when deciding whether or not to adopt FLACS in their practice. Then I will tell you what my nine cataract surgeon partners and I are doing at Minnesota Eye Consultants, or MEC.
First, a few disclosures. I was on the medical advisory board for LenSx from inception and acquired in collaboration with Sightpath Medical one of the first 10 LenSx femtosecond lasers. I worked with them to develop the mobile FLACS program, and the laser we used was MoFe#1. The Sightpath laser would be unloaded into my anterior chamber-based operating suite on Sunday, I would operate with it on Monday, and then they would load it back onto a specially designed truck and drive around the region until bringing it back the following Monday. We confirmed that FLACS could be safely performed using a mobile shared-access model. I also have worked with the Lensar femtosecond laser and currently serve on the Lensar board of directors. At one time or another I have owned a small amount of equity in LenSx, Lensar and Sightpath. I am a consultant for J&J Vision, Alcon and Bausch + Lomb, who all have commercial femtosecond lasers available in America. One could argue that few individuals in the world want FLACS to be a greater success than me.
Now let me focus on my clinical experience and impressions. In my hands, FLACS makes an excellent limbal or corneal relaxing incision. However, I like the clear corneal incision I make with a metal or diamond blade better. In the first 2 years I worked with the LenSx laser, I did a small 50-patient prospective, nonrandomized, observational trial at MEC in patients with 1 D to 3 D of corneal astigmatism. I marked the steeper meridian using a Mastel keratoscope, performed the FLACS relaxing incisions using my own Lindstrom Arc-T diamond knife nomogram, and verified IOL power with intraoperative aberrometry. I achieved 92% within 0.5 D of target and 100% within 1 D at 3 months postoperative. This was an uncontrolled series, but Liz Yeu, MD, in the accompanying cover story and as a presenter at the recent Kiawah Eye meeting, produced even better results that were superior to her outcomes with manual cataract surgery.
FLACS can perform a beautiful limbal or corneal relaxing incision and generate excellent early refractive outcomes. However, after following my thousands of incisional keratotomy patients for up to 40 years now, I find the long-term results of corneal incisional keratotomy, whether for astigmatism or myopia, are not reliably stable. In the face of excellent personal and colleague outcomes with limbal and corneal relaxing incisions, I still prefer a toric IOL because of long-term stability. When a toric IOL is too much, I perform an on-axis clear corneal incision. I prefer treating astigmatism with toric IOLs and on-axis incisions, neither of which requires a femtosecond laser. My concerns about late stability have led me to stop doing incisional keratotomy with a diamond knife or FLACS. One surgeon’s opinion, definitely open to debate, but that is the purpose of this commentary.
My enhancement tool when needed is LASIK or PRK. In just more than 160 eyes enhanced with the excimer laser, my mean outcome was within 0.12 D of target, and I had no residual sphere of cylinder over 0.75 D after excimer laser enhancement. So, my current approach to astigmatism management is a toric IOL and/or an on-axis incision when appropriate followed by a PRK or LASIK enhancement as needed.
Because astigmatism management is the primary indication in the U.S. for FLACS, my preferences for astigmatism management have reduced my current personal FLACS usage to zero. The same is true for nearly all of my nine partners at MEC. One of us has continued to use FLACS enough to give our fellows experience and make it available to highly interested patients, but we as a group at MEC are infrequent users of FLACS today. As a group we do a large number of extremely complex cases, and six of us who do cataract surgery are fellowship trained in cornea and four in glaucoma. While we have not performed a carefully designed prospective study of FLACS vs. manual cataract surgery in complex cases, our clinical impression is that they are equivalent, and none of us are currently recommending FLACS for complex cases.
The capsulorrhexis created by FLACS is to me a thing of beauty. It can be any size, nearly perfectly round, centered on the visual axis, which is my preference, and allows perfect IOL overlap. Unfortunately, data proving a better visual acuity outcome regarding effective lens position and tilt have been challenging to achieve. Using Snellen visual acuities as the outcome measure, most studies show no benefit. More recent studies looking at higher-order aberrations suggest that a perfect capsulorrhexis with 360° symmetrical IOL optic overlap may reduce induced coma. This small improvement in coma should lead to improved contrast sensitivity, which could be especially important in diffractive multifocal IOLs and low-contrast tasks such as night driving. If the early work in this area is confirmed, this will be our first good evidence that FLACS might generate a superior visual outcome, especially in the premium IOL space. If confirmed, this might draw me back to FLACS for the premium patient, but I am also now evaluating a new technology, the Mynosys Zepto for capsulorrhexis.
For me, Zepto takes less time, is less expensive and generates an equally beautiful capsulorrhexis that can be centered on the visual axis and, according to published studies by my good friends Vance Thompson, MD, and John Berdahl, MD, is nearly three times stronger than the capsulorrhexis performed with a femtosecond laser. There remains controversy concerning the incidence of anterior capsular rim tears with each method of capsulorrhexis, but to date in small series, I have seen none with either Zepto or FLACS, and my incidence in many more cases with manual is low. Zepto today comes in only one diameter, and the current diameter is not perfect for my preferred supracapsular phacoemulsification, but I anticipate it will become available in other sizes in the near future. If the data continue to support the superiority of a so-called perfectly shaped, sized and visual axis-centered “refractive capsulorrhexis,” I see myself adopting Zepto and not returning to FLACS. However, for those who already own a femtosecond laser, I see the perfect capsulorrhexis that enhances refractive outcomes as a potential driver of increased use and growing adoption.
FLACS can, for some surgeons, enhance nuclear disassembly during phacoemulsification, and some series show reduced 1-day cornea edema as measured by pachymetry and reduced endothelial cell loss. For the U.S. surgeon, most lenses are fairly soft, and with today’s high-quality phacoemulsification machines and viscoelastics, I do not see nuclear softening and reduced intraoperative endothelial cell damage as a major driver of FLACS for most surgeons. It is not for our group of six cornea fellowship-trained surgeons whose practices are full of patients with Fuchs’ dystrophy. I am doing some Zepto capsulorrhexes and am excited about the prospect of the perfect capsulorrhexis, reducing coma and enhancing refractive outcomes. I believe this so-called “refractive capsulorrhexis” is a meaningful advance, and if confirmed, I predict it will generate growth in Zepto and FLACS and might bring FLACS back into my personal practice.
There are also other technologies in development that are capable of generating a near-perfect capsulorrhexis, such as CAPSULaser (Excel-Lens), and the potential value proposition is real for both the patient and surgeon — better vision. I expect laser cataract surgery to progress and evolve as significant financial and human capital is invested in the field. In addition, if femtosecond lasers can not only assist in our cataract surgery, but also adjust power of our implanted IOLs, which appears possible in early research, we will likely all find ourselves driven to again adopt femtosecond lasers into our refractive cataract practices.
Full adoption of new technologies takes decades. During the early stages of adoption, many surgeons are like me. They move in and out of the technology until it is refined and its benefits are fully appreciated. A period of irrational exuberance for a new technology is often followed by a period of equally irrational disillusionment that evolves into either abandonment or rational adoption of the technology. I believe many surgeons are today at the stage of irrational disillusionment in the use of FLACS. While no one can predict the future, I do not see FLACS being abandoned. The next stage to me will be rational adoption, and most exciting to me is the opportunity to perform a “refractive capsulorrhexis” and adjust IOL power postoperatively to enhance our patients’ visual outcomes.
Disclosure: Lindstrom reports relevant financial disclosures for LenSx, Lensar, Sightpath, J & J Vision, Bausch + Lomb, Alcon and Mynosys.