title: Prefilled syringe needles versus standard removable needles for intravitreous injection.
abstract: OBJECTIVE
  To investigate differences in the scleral resistance between standard disposable 27 gauge (G) needle versus the Macugen prefilled syringe needle.
  
  
  METHODS
  Observational study at one eye center. One injecting physician performed 46 intravitreous injections using standard Becton Dickinson 27 G needles and 71 intravitreous injections using Macugen needles during January to May 2005. The procedure in two patients was videotaped and analyzed frame by frame. Microphotographs of used needles were analyzed.
  
  
  RESULTS
  There were no complications during the injection procedure in either group. Microphotographic analysis after injection revealed 3 and 5 facets on standard 27 G needle and Macugen needles, respectively. The bevel forming the tip of the 27 G needle was steeper and longer than that of the Macugen needle. The inside diameter in the standard 27 G needle was 220 microm versus 210 microm in the Macugen needle.
  
  
  CONCLUSIONS
  There are differences in needle design between commonly used disposable 27 G needles and 27 G Macugen needles which result in higher resistance to penetration with Macugen needle. Careful needle design is an important concern in manufacturing prefilled syringes with needles attached to them.
authors.affiliation: Jacobs Retina Center, University of California San Diego, Shiley Eye Center, La Jolla 92037, USA.
authors.forename: Igor
authors.initials: I
authors.lastname: Kozak
authors.forename: April
authors.initials: A
authors.lastname: Dean
authors.forename: Thomas M
authors.initials: TM
authors.lastname: Clark
authors.forename: Iryna
authors.initials: I
authors.lastname: Falkenstein
authors.forename: William R
authors.initials: WR
authors.lastname: Freeman
mesh_terms: D000818:Animals; D052157:Aptamers, Nucleotide / Q000008:administration & dosage; D004867:Equipment Design; D006801:Humans; D007267:Injections / Q000295:instrumentation*; D009339:Needles; D011312:Pressure; D011677:Punctures; D012590:Sclera / Q000503:physiopathology; D013552:Swine; D013594:Syringes; D014741:Video Recording; D014822:Vitreous Body / Q000187:drug effects*
chemical_list: D052157:Aptamers, Nucleotide; C495058:pegaptanib