title: Model of pulsatile-flow of aqueous humor through the iris-lens canal.
abstract: OBJECTIVE
  To present a model of pulsatile-flow of aqueous humor from posterior (PC) to anterior chamber (AC) and to analyze the sensitivity of this novel model in detecting typical high risk conditions predisposing to pupillary block.
  
  
  METHODS
  The model assumes noncontinuous flow of aqueous through the iris-lens canal. Aqueous that fills the canal will be ejected toward the AC-side of the canal at certain time intervals, and between 2 events of aqueous ejection there is no actual flow through this canal. Pupillary pumping rate (PPR) was calculated from the aqueous flow rate and the calculated volume of iris-lens canal.
  
  
  RESULTS
  PPR values were generated by incorporating pupillary diameter (1 to 8 mm), aqueous flow rate (1 to 2.5 microL/min), and iris-lens canal width (0.5 to 2 mm) and height (3-9 microm) in numerical experimentation with the present model. PPR showed inverse dependence on iris-lens canal height and pupillary diameter and was directly proportional to aqueous flow rate, in agreement with the steady-flow model. However, contrary to the steady-flow model, PPR showed inverse dependence on iris-lens canal width and predicted the anticipated PC-AC pressure gradient changes at simulated light-dark transition in eyes of patients with clinically narrow angles and ultrasound biomicroscopy evidenced pupillary block.
  
  
  CONCLUSIONS
  Upon the incorporation of real ultrasound biomicroscopy measurements in numerical experimentations with both models, the present pulsatile-flow model, contrary to the steady-flow model, showed good predictability of PC-AC pressure gradient changes in a typical condition predisposing to pupillary block.
authors.affiliation: Unit 598, Physiopathology of Ocular Diseases and Therapeutic Innovations, National Institute of Health and Medical Research (INSERM U598), Paris, France. adisacom@palnet.com
authors.forename: Muhammad
authors.initials: M
authors.lastname: Abdulrazik
mesh_terms: D000867:Anterior Chamber / Q000502:physiology*; D001082:Aqueous Humor / Q000502:physiology*; D006801:Humans; D007498:Iris / Q000378:metabolism*; D007908:Lens, Crystalline / Q000378:metabolism*; D033401:Microscopy, Acoustic; D008954:Models, Biological; D011673:Pulsatile Flow / Q000502:physiology*; D011680:Pupil / Q000502:physiology