title: [Gradient-index (GRIN) endoscopic examinations from the inner structures of the optic nerve meninges].
abstract: BACKGROUND
  Due to the excellent image quality and the small outer diameter of the GRIN-(gradient index) endoscope tips we were able to examine the subdural and the subarachnoidal space of the optic nerve meninges by endoscopy. This examination was performed to obtain more information about the inner structure of the optic nerve meninges.
  
  
  METHODS
  In this post-mortem study 7 optic nerves were examined from the chiasm to the globe by GRIN endoscopy (Volpi, Schlieren, Switzerland), with an outer diameter of 0.89 mm, integrated optic of 0.5 mm diameter and an integrated fluid channel of 0.2 mm diameter.
  
  
  RESULTS
  In all cases the endoscopic examination of the optic nerve meninges was technically easy to perform. It was possible to study the inner surface of the nerve sheaths and the nerve sheath spaces in close-up. We found horizontal and vertical cords on the inner surface of the dura mater, which could tighten by movements of the optic nerve.
  
  
  CONCLUSIONS
  With a gradient-index (GRIN) endoscope we obtained new information about the inner structure of the optic nerve meninges. New theories about the changes of the optic nerve meninges during movements of the optic nerve may evolve from this study. Further studies with this new method should be encouraged.
authors.affiliation: Universitäts-Augenklinik Basel, Schweiz.
authors.forename: Frank Michael
authors.initials: FM
authors.lastname: Sens
authors.forename: Hanspeter Esriel
authors.initials: HE
authors.lastname: Killer
authors.forename: Peter
authors.initials: P
authors.lastname: Meyer
mesh_terms: D004867:Equipment Design; D006801:Humans; D007089:Image Enhancement / Q000295:instrumentation*; D008578:Meninges / Q000033:anatomy & histology*; D019721:Ophthalmoscopes; D009897:Optic Chiasm / Q000033:anatomy & histology; D009900:Optic Nerve / Q000033:anatomy & histology*; D012016:Reference Values; D013346:Subarachnoid Space / Q000033:anatomy & histology*; D013355:Subdural Space / Q000033:anatomy & histology*