title: A theoretical model to allow prediction of the CSF pressure from observations of the retinal venous pulse.
abstract: OBJECTIVE
  There is no easy way to estimate the intracranial pressure (ICP) noninvasively. The retinal vein can exhibit large amplitude oscillations at the level of the lamina cribrosa under certain circumstances. The aims of this study were to develop a theoretical understanding of the conditions required to establish this vigorous oscillatory behavior and to determine whether observations of it could lead to a noninvasive estimate of the ICP.
  
  
  METHODS
  A mathematical model was constructed in which the central retinal vein was modeled as 2 Starling resistors in series, 1 located in the eye and the other in the cerebrospinal fluid (CSF) space, separated by a region where it was not collapsible, corresponding to its course within the optic nerve itself. Intraocular pressure (IOP) and ICP were modeled as sinusoidal wave forms.
  
  
  RESULTS
  The model predicted an approximately linear relationship between the IOP and the ICP at the point of onset of oscillatory behavior. The predicted onset IOP also depended weakly on the retinal blood flow rate and on vein diameter and was only mildly sensitive to the phase difference between the two pressure waveforms. The predicted onset curve showed encouraging agreement with measurements in canines.
  
  
  CONCLUSIONS
  The model suggested that it may be possible to estimate the ICP from observations of the retinal venous pulse by using a modified form of ophthalmodynamometry.
authors.affiliation: School of Mathematics and Statistics, University of Glasgow, Glasgow, United Kingdom.
authors.forename: Peter S
authors.initials: PS
authors.lastname: Stewart
authors.affiliation: School of Mathematics, University of Manchester, Manchester, United Kingdom.
authors.forename: Oliver E
authors.initials: OE
authors.lastname: Jensen
authors.affiliation: Department of Ophthalmology, Queen's Medical Centre, Nottingham, United Kingdom.
authors.forename: Alexander J E
authors.initials: AJ
authors.lastname: Foss
mesh_terms: D015170:Cerebrospinal Fluid Pressure / Q000502:physiology*; D005901:Glaucoma / Q000175:diagnosis / Q000503:physiopathology*; D006801:Humans; D007429:Intraocular Pressure / Q000502:physiology; D008962:Models, Theoretical; D011237:Predictive Value of Tests; D012039:Regional Blood Flow; D012160:Retina / Q000503:physiopathology; D012169:Retinal Vein / Q000503:physiopathology*; D014690:Venous Pressure / Q000502:physiology*
keywords: cerebrospinal fluid pressure; glaucoma; retinal venous pulse