title: Corneal tissue interactions of a new 345 nm ultraviolet femtosecond laser.
abstract: OBJECTIVE
  To assess the suitability of a new 345 nm ultraviolet (UV) femtosecond laser for refractive surgery.
  
  
  METHODS
  Department of Ophthalmology, University of Erlangen-Nürnberg, Erlangen, Germany.
  
  
  METHODS
  Experimental study.
  
  
  METHODS
  Twenty-five porcine corneas were used for stromal flap or lamellar bed creation (stromal depth, 150 μm) and 15 rabbit corneas for lamellar bed creation near the endothelium. Ultraviolet femtosecond laser cutting-line morphology, gas formation, and keratocyte death rate were evaluated using light and electron microscopy and compared with a standard infrared (IR) femtosecond laser. Endothelial cell survival was examined after application of a laser cut near the endothelium.
  
  
  RESULTS
  Flaps created by the UV laser were lifted easily. Gas formation was reduced 4.2-fold compared with the IR laser (P = .001). The keratocyte death rate near the interface was almost doubled; however, the death zone was confined to a region within 38 μm ± 10 (SD) along the cutting line. Histologically and ultrastructurally, a distinct and continuous cutting line was not found after UV femtosecond laser application if flap lifting was omitted and standard energy parameters were used. Instead, a regular pattern of vertical striations, presumably representing self-focusing induced regions of optical tissue breakdown, were identified. Lamellar bed creation with standard energy parameters 50 μm from the endothelium rendered the endothelial cells intact and viable.
  
  
  CONCLUSIONS
  The new 345 nm femtosecond laser is a candidate for pending in vivo trials and future high-precision flap creation, intrastromal lenticule extraction, and ultrathin Descemet-stripping endothelial keratoplasty.
  
  
  BACKGROUND
  Mr. Klenke and Ms. Skerl were paid employees of Wavelight GmbH when the study was performed. Dr. Seiler is a scientific consultant to Wavelight GmbH. No other author has a financial or proprietary interest in any material or method mentioned.
authors.affiliation: From the Department of Ophthalmology (Hammer, Petsch, Kruse, Menzel-Severing) and the Department of Anatomy II (Hammer, Paulsen), Friedrich-Alexander-University of Erlangen-Nürnberg, Wavelight GmbH (Klenke, Skerl), Erlangen, Germany; the Medical Research Institute (Skerl), University of Dundee, Ninewells Hospital & Medical School, Dundee, Scotland, United Kingdom; the Institut für Refraktive und Ophthalmo-Chirurgie (Seiler), Zürich, Switzerland. Electronic address: c.m.hammer@t-online.de.
authors.forename: Christian M
authors.initials: CM
authors.lastname: Hammer
authors.affiliation: From the Department of Ophthalmology (Hammer, Petsch, Kruse, Menzel-Severing) and the Department of Anatomy II (Hammer, Paulsen), Friedrich-Alexander-University of Erlangen-Nürnberg, Wavelight GmbH (Klenke, Skerl), Erlangen, Germany; the Medical Research Institute (Skerl), University of Dundee, Ninewells Hospital & Medical School, Dundee, Scotland, United Kingdom; the Institut für Refraktive und Ophthalmo-Chirurgie (Seiler), Zürich, Switzerland.
authors.forename: Corinna
authors.initials: C
authors.lastname: Petsch
authors.affiliation: From the Department of Ophthalmology (Hammer, Petsch, Kruse, Menzel-Severing) and the Department of Anatomy II (Hammer, Paulsen), Friedrich-Alexander-University of Erlangen-Nürnberg, Wavelight GmbH (Klenke, Skerl), Erlangen, Germany; the Medical Research Institute (Skerl), University of Dundee, Ninewells Hospital & Medical School, Dundee, Scotland, United Kingdom; the Institut für Refraktive und Ophthalmo-Chirurgie (Seiler), Zürich, Switzerland.
authors.forename: Jörg
authors.initials: J
authors.lastname: Klenke
authors.affiliation: From the Department of Ophthalmology (Hammer, Petsch, Kruse, Menzel-Severing) and the Department of Anatomy II (Hammer, Paulsen), Friedrich-Alexander-University of Erlangen-Nürnberg, Wavelight GmbH (Klenke, Skerl), Erlangen, Germany; the Medical Research Institute (Skerl), University of Dundee, Ninewells Hospital & Medical School, Dundee, Scotland, United Kingdom; the Institut für Refraktive und Ophthalmo-Chirurgie (Seiler), Zürich, Switzerland.
authors.forename: Katrin
authors.initials: K
authors.lastname: Skerl
authors.affiliation: From the Department of Ophthalmology (Hammer, Petsch, Kruse, Menzel-Severing) and the Department of Anatomy II (Hammer, Paulsen), Friedrich-Alexander-University of Erlangen-Nürnberg, Wavelight GmbH (Klenke, Skerl), Erlangen, Germany; the Medical Research Institute (Skerl), University of Dundee, Ninewells Hospital & Medical School, Dundee, Scotland, United Kingdom; the Institut für Refraktive und Ophthalmo-Chirurgie (Seiler), Zürich, Switzerland.
authors.forename: Friedrich
authors.initials: F
authors.lastname: Paulsen
authors.affiliation: From the Department of Ophthalmology (Hammer, Petsch, Kruse, Menzel-Severing) and the Department of Anatomy II (Hammer, Paulsen), Friedrich-Alexander-University of Erlangen-Nürnberg, Wavelight GmbH (Klenke, Skerl), Erlangen, Germany; the Medical Research Institute (Skerl), University of Dundee, Ninewells Hospital & Medical School, Dundee, Scotland, United Kingdom; the Institut für Refraktive und Ophthalmo-Chirurgie (Seiler), Zürich, Switzerland.
authors.forename: Friedrich E
authors.initials: FE
authors.lastname: Kruse
authors.affiliation: From the Department of Ophthalmology (Hammer, Petsch, Kruse, Menzel-Severing) and the Department of Anatomy II (Hammer, Paulsen), Friedrich-Alexander-University of Erlangen-Nürnberg, Wavelight GmbH (Klenke, Skerl), Erlangen, Germany; the Medical Research Institute (Skerl), University of Dundee, Ninewells Hospital & Medical School, Dundee, Scotland, United Kingdom; the Institut für Refraktive und Ophthalmo-Chirurgie (Seiler), Zürich, Switzerland.
authors.forename: Theo
authors.initials: T
authors.lastname: Seiler
authors.affiliation: From the Department of Ophthalmology (Hammer, Petsch, Kruse, Menzel-Severing) and the Department of Anatomy II (Hammer, Paulsen), Friedrich-Alexander-University of Erlangen-Nürnberg, Wavelight GmbH (Klenke, Skerl), Erlangen, Germany; the Medical Research Institute (Skerl), University of Dundee, Ninewells Hospital & Medical School, Dundee, Scotland, United Kingdom; the Institut für Refraktive und Ophthalmo-Chirurgie (Seiler), Zürich, Switzerland.
authors.forename: Johannes
authors.initials: J
authors.lastname: Menzel-Severing
mesh_terms: D000818:Animals; D002470:Cell Survival; D060527:Corneal Keratocytes / Q000648:ultrastructure; D003319:Corneal Stroma / Q000473:pathology / Q000601:surgery*; D004728:Endothelium, Corneal / Q000648:ultrastructure; D020287:In Situ Nick-End Labeling; D054018:Lasers, Excimer / Q000627:therapeutic use*; D045423:Microbubbles; D008854:Microscopy, Electron; D011817:Rabbits; D013524:Surgical Flaps; D013552:Swine; D014466:Ultraviolet Rays