Femtosecond Laser–Assisted Cataract Surgery
In 2010, the US FDA approved femtosecond lasers for cataract extraction. Well known to refractive surgeons, these Nd:glass lasers generate focused, ultrashort pulses (10−15 s) at a wavelength of 1053 nm (in the near-infrared region), creating cavitation bubbles within the tissues by photodisruption. Because femtosecond laser technology virtually eliminates collateral damage, it can be used to dissect tissue on a microscopic scale, enabling creation of a capsulotomy, lens fragmentation patterns, corneal relaxing incisions, and clear corneal incisions, if desired (Video 8-9).
Femtosecond laser treatment before cataract extraction. Courtesy of Eric D. Snyder, MD.
Before femtosecond laser–assisted surgery, the treatment plan is entered into the system’s computer. For a capsulotomy, the intended size and centration method are selected. For lens fragmentation, the pattern used to segment and soften the lens is chosen (ie, available patterns vary by machine). For corneal relaxing incisions, the optical zone, arc length, axis, and depth are selected. The laser can create either anteriorly penetrating corneal relaxing incisions or intrastromal (nonpenetrating) corneal relaxing incisions (see Chapter 9). For clear corneal incisions, the location, size, and wound architecture are selected.
After the eye has been dilated, the patient assumes a supine position. A patient interface docks the patient’s eye to the laser unit. The system measures and maps the dimensions of the anterior segment with 3-dimensional spectral-domain optical coherence tomography (SD-OCT) or Scheimpflug imaging. The surgeon confirms the intended treatment protocol and ocular landmarks, including the proper axis orientation of any intended astigmatic treatment, and then activates the femtosecond laser by depressing the foot pedal. During lens fragmentation, gas released from the cavitation bubbles can accumulate between the nucleus and the capsule, creating a pneumodissection effect, which may reduce the need for subsequent hydrodissection. When the laser portion of the procedure is finished, the patient is undocked; some surgeons instill additional eyedrops at this point to address possible laser-induced miosis.
In the operating room, the patient is then prepped and draped for cataract surgery in the typical fashion and positioned beneath the operating microscope for cataract extraction using phacoemulsification (Video 8-10). If clear corneal incisions were created as part of the laser treatment, the surgeon dissects them open. The surgeon verifies that the capsulotomy is complete, carefully removes the anterior capsule with forceps, and may perform gentle hydrodissection and nucleus rotation before proceeding with nucleus removal. To titrate any anteriorly penetrating corneal relaxing incisions and increase their astigmatic effect, the surgeon may gently open them, either during surgery or in the postoperative period at the slit lamp. Methods of marking the intended axis of toric IOL alignment, including small astigmatically neutral corneal incisions or small tabs on the capsulotomy pattern, vary by laser platform.
Cataract extraction after femtosecond laser treatment. Courtesy of Charles Cole, MD.
Potential complications related to femtosecond laser–assisted cataract surgery include subconjunctival hemorrhage from the patient interface; incomplete capsulotomy, which may lead to a radial capsular tear; and buildup of gas bubbles within the capsular bag, which can lead to posterior capsule rupture with aggressive hydrodissection.
Since the femtosecond laser was introduced into cataract surgery, its utility has been intensely debated within the ophthalmological community. Proponents of this approach extol its precision, reproducibility, and safety. Others have raised concerns about the higher costs involved and point out that similar results can be achieved by small-incision phacoemulsification as it is currently practiced.
Currently, 5 femtosecond laser technology platforms for cataract surgery are commercially available in the United States: Catalys (Johnson & Johnson Vision), LenSx (Alcon Laboratories), Lensar (LENSAR), Victus (Bausch + Lomb), and Femto LDV Z8 (Ziemer USA).
Excerpted from BCSC 2020-2021 series: Section 11 - Lens and Cataract. For more information and to purchase the entire series, please visit https://www.aao.org/bcsc.