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Femtosecond laser continues to make inroads in cataract surgery
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Femtosecond lasers create ultrashort high-energy pulses in rapid succession. These pulses strip electrons off molecules, creating optical breakdown and plasma formation. In the process, a cavitation bubble is created, which can cause tissue separation with minimal collateral tissue damage. The ultrashort duration and small size of the pulse, less than 3 µm, eliminate any meaningful heat in the tissue. The process of cutting with a femtosecond laser is called photodisruption.
While minimal heat is generated, there is associated inflammation and inflammatory mediators, including prostaglandins, leukotrienes and other cytokines, are released. My strong impression is that incisions made with the femtosecond laser generate more inflammation than that associated with a microkeratome or metal or diamond keratome. In some cases, this increased inflammation can be good — for example, when generating a stronger adhesion at the edge of a LASIK flap. In other cases, such as interface haze or intraoperative miosis after femtosecond laser anterior capsulotomy in cataract surgery, the increased inflammation can be undesirable.
Femtosecond lasers were first applied to LASIK surgery in 2001, and Ron Kurtz MD, a retina specialist working with IntraLase, pioneered this effort. I currently do all my LASIK flaps with the IntraLase femtosecond laser (Abbott Medical Optics). While select surgeons can match the safety and precision of a laser-generated flap using a bladed microkeratome, most cannot. Thus, the femtosecond laser is dominant as a flap-maker in LASIK in advanced countries. Some surgeons also find the laser helpful in lamellar and penetrating keratoplasty, but reimbursement barriers have limited its adoption.
Femtosecond laser application to cataract surgery was pioneered by two retina surgeons, with Mark Blumenkranz, MD, of OptiMedica, now owned by AMO, joining Kurtz, of LenSx, now owned by Alcon. Of course, many others, too numerous to name, played pioneering roles as well. Zoltan Nagy, MD, of Budapest, Hungary, did the earliest human cases in the world, and Steve Slade, MD, was our first user in the United States, both working with LenSx. Early adopters of the femtosecond laser in cataract surgery were attracted by computer-driven precision. In the case of cataract surgery, advanced intraoperative imaging, usually by optical coherence tomography, was also required, making the instruments even more expensive.
While I was honored to obtain one of the first 10 lasers in the U.S. for cataract surgery, femtosecond laser-assisted cataract surgery does not dominate in my personal or group practice. I still find bladed incisions, whether metal or gem based, superior to what I can generate with the laser. I like the capsulorrhexis precision in regards to both size and shape and have not experienced anterior rim tears in any cases. Still, I can make a pretty good continuous-tear anterior capsulotomy manually. Nuclear softening is interesting, but patterns are still evolving. Corneal relaxing incisions are superior to what I can do manually, but toric IOLs are likely to be more popular for most surgeons.
In the United States, the restriction in indication to refractive cataract surgery limits adoption. Nonetheless, femtosecond laser-assisted cataract surgery is gaining in popularity worldwide. As laser costs diminish, I see increasing adoption worldwide. Some have predicted that femtosecond lasers will be abandoned by cataract surgeons in the decade ahead. I personally disagree and expect them to become simpler, cheaper and, through shared access models including mobile lasers, available to most surgeons in the advanced world. The major strategic companies in our field share this opinion and are investing heavily to make it happen. I predict they will succeed.