title: Finesse of transparent tissue cutting by ultrafast lasers at various wavelengths.
abstract: Transparent ocular tissues, such as the cornea and crystalline lens, can be ablated or dissected using short-pulse lasers. In refractive and cataract surgeries, the cornea, lens, and lens capsule can be cut by producing dielectric breakdown in the focus of a near-infrared (IR) femtosecond laser, which results in explosive vaporization of the interstitial water, causing mechanical rupture of the surrounding tissue. Here, we compare the texture of edges of lens capsule cut by femtosecond lasers with IR and ultraviolet (UV) wavelengths and explore differences in interactions of these lasers with biological molecules. Scanning electron microscopy indicates that a 400-nm laser is capable of producing very smooth cut edges compared to 800 or 1030 nm at a similar focusing angle. Using gel electrophoresis and liquid chromatography/mass spectrometry, we observe laser-induced nonlinear breakdown of proteins and polypeptides by 400-nm femtosecond pulses above and below the dielectric breakdown threshold. On the other hand, 800-nm femtosecond lasers do not produce significant dissociation even above the threshold of dielectric breakdown. However, despite this additional interaction of UV femtosecond laser with proteins, we determine that efficient cutting requires plasma-mediated bubble formation and that remarkably smooth edges are the result of reduced thresholds and smaller focal volume.
authors.affiliation: Stanford University, Department of Applied Physics, 452 Lomita Mall, Stanford, California 94305, United States.
authors.forename: Jenny
authors.initials: J
authors.lastname: Wang
authors.affiliation: Abbott Medical Optics, 1310 Moffett Park Drive, Sunnyvale, California 94089, United States.
authors.forename: Georg
authors.initials: G
authors.lastname: Schuele
authors.affiliation: Stanford University, Department of Ophthalmology, 452 Lomita Mall, Stanford, California 94305, United StatesdStanford University, Hansen Experimental Physics Laboratory, 452 Lomita Mall, Stanford, California 94305, United States.
authors.forename: Daniel
authors.initials: D
authors.lastname: Palanker
mesh_terms: D000818:Animals; D002417:Cattle; D003315:Cornea / Q000601:surgery*; D045604:Extracellular Fluid; D006801:Humans; D007259:Infrared Rays; D053685:Laser Therapy / Q000295:instrumentation* / Q000379:methods; D007834:Lasers; D007908:Lens, Crystalline / Q000601:surgery*; D008027:Light; D013058:Mass Spectrometry; D008855:Microscopy, Electron, Scanning; D016011:Normal Distribution; D055095:Optics and Photonics; D010455:Peptides / Q000737:chemistry; D010777:Photochemistry; D011506:Proteins / Q000737:chemistry; D012710:Serum Albumin, Bovine / Q000737:chemistry; D014466:Ultraviolet Rays; D014867:Water
chemical_list: D010455:Peptides; D011506:Proteins; D014867:Water; D012710:Serum Albumin, Bovine