title: Effect of gravity in long-term vitreous tamponade: in vivo investigation using perfluorocarbon liquids and semi-fluorinated alkanes.
abstract: OBJECTIVE
  In order to investigate whether gravity is the reason for retinal degeneration in long-term vitreous tamponade, perfluorohexyloctane (F6H8), perfluorodecalin (PFD), and a mixture of F6H8/PFD were compared.
  
  
  METHODS
  Each group of 5 rabbits received a 3-month tamponade with either PFD (pure) (1.93 g/cm(3)), F6H8 (pure) (1.33 g/cm(3)), or a 1:1 mixture of F6H8/PFD (1.62 g/cm(3)). Electroretinograms (ERG) were performed pre- and postoperatively. Lower and upper retinal areas were compared using immunohistochemical methods. Transmission electron microscopy was performed to investigate alterations in the photoreceptors.
  
  
  RESULTS
  All three substances were tolerated well in rabbit eyes for up to 3 months. Dispersion was seen earliest with PFD and latest with pure F6H8. None of the substances demonstrated inflammatory reactions or vascular alterations. ERGs were not considerably altered with any of the substances. Histology of the retina showed alterations in the cell counts within the inner and outer nuclear layer that were not attributable to the gravity of the tamponading agent.
  
  
  CONCLUSIONS
  In contrast to previously published work, this study did not detect any tamponade-related structural damage of the retina after a 3-months tamponade in the rabbit model. Based upon this study, we conclude that gravity might not be causally linked to retinal damage.
authors.affiliation: Department of Vitreoretinal Surgery, Center for Ophthalmology, University of Cologne, Kerpener Strasse 62, 50924, Cologne, Germany. jerzy.mackiewicz@am.lublin.pl
authors.forename: Jerzy
authors.initials: J
authors.lastname: Mackiewicz
authors.forename: Kristel
authors.initials: K
authors.lastname: Maaijwee
authors.forename: Christoph
authors.initials: C
authors.lastname: Lüke
authors.forename: Norbert
authors.initials: N
authors.lastname: Kociok
authors.forename: Wilfried
authors.initials: W
authors.lastname: Hiebl
authors.forename: Hasso
authors.initials: H
authors.lastname: Meinert
authors.forename: Antonia M
authors.initials: AM
authors.lastname: Joussen
mesh_terms: D000818:Animals; D002452:Cell Count; D004338:Drug Combinations; D004596:Electroretinography / Q000187:drug effects; D005466:Fluorocarbons / Q000008:administration & dosage / Q000633:toxicity*; D020287:In Situ Nick-End Labeling; D010775:Photic Stimulation; D020419:Photoreceptor Cells, Vertebrate / Q000187:drug effects / Q000648:ultrastructure; D011817:Rabbits; D012160:Retina / Q000187:drug effects* / Q000648:ultrastructure; D012162:Retinal Degeneration / Q000139:chemically induced; D013046:Specific Gravity; D014822:Vitreous Body / Q000187:drug effects*
chemical_list: D004338:Drug Combinations; D005466:Fluorocarbons; C008805:perfluorodecalin; C118616:perfluorohexyl-octan