Herbert A Reitsamer1, Jeffrey W Kiel. 1. Department of Physiology, University of Vienna Medical School, Vienna, Austria. herbert.reitsamer@univie.ac.at
Abstract
PURPOSE: To determine the relationship between ciliary blood flow and aqueous flow by changing the mean arterial pressure (MAP) mechanically under controlled conditions in an animal model. METHODS: In anesthetized rabbits, MAP and intraocular pressure (IOP) were measured by direct cannulation. MAP was controlled with occluders placed on the aorta and vena cava. In group 1 (n = 22), aqueous flow was measured by fluorophotometry. In group 2 (n = 21), ciliary blood flow was measured by laser Doppler flowmetry. In separate subgroups, measurements were made for 60 minutes at the control MAP of 70 mm Hg and for an additional 60 minutes at target MAPs of 80, 55, or 40 mm Hg. RESULTS: The target MAPs achieved perfusion pressures (MAP - IOP) of 33.6 +/- 1.0, 43.5 +/- 0.7, 51.9 +/- 0.6, and 65.2 +/- 0.9 mm Hg. Ciliary blood flow was unaffected by increased perfusion pressure, but decreased progressively as perfusion pressure was lowered. Aqueous flow decreased only at the lowest perfusion pressure. CONCLUSIONS: Under control conditions in anesthetized rabbits, aqueous production is independent of ciliary blood flow until ciliary blood flow declines below 74% of control. At ciliary blood flow below this critical level, aqueous production is blood flow dependent.
PURPOSE: To determine the relationship between ciliary blood flow and aqueous flow by changing the mean arterial pressure (MAP) mechanically under controlled conditions in an animal model. METHODS: In anesthetized rabbits, MAP and intraocular pressure (IOP) were measured by direct cannulation. MAP was controlled with occluders placed on the aorta and vena cava. In group 1 (n = 22), aqueous flow was measured by fluorophotometry. In group 2 (n = 21), ciliary blood flow was measured by laser Doppler flowmetry. In separate subgroups, measurements were made for 60 minutes at the control MAP of 70 mm Hg and for an additional 60 minutes at target MAPs of 80, 55, or 40 mm Hg. RESULTS: The target MAPs achieved perfusion pressures (MAP - IOP) of 33.6 +/- 1.0, 43.5 +/- 0.7, 51.9 +/- 0.6, and 65.2 +/- 0.9 mm Hg. Ciliary blood flow was unaffected by increased perfusion pressure, but decreased progressively as perfusion pressure was lowered. Aqueous flow decreased only at the lowest perfusion pressure. CONCLUSIONS: Under control conditions in anesthetized rabbits, aqueous production is independent of ciliary blood flow until ciliary blood flow declines below 74% of control. At ciliary blood flow below this critical level, aqueous production is blood flow dependent.
Authors: C Strohmaier; R M Werkmeister; B Bogner; C Runge; F Schroedl; H Brandtner; W Radner; L Schmetterer; J W Kiel; G Grabner; H A Reitsamer Journal: Exp Eye Res Date: 2011-04-01 Impact factor: 3.467
Authors: Marcel Y Avila; Alejandro Múnera; Arcadio Guzmán; Chi Wai Do; Zhao Wang; Richard A Stone; Mortimer M Civan Journal: Invest Ophthalmol Vis Sci Date: 2005-09 Impact factor: 4.799
Authors: Barbara Bogner; Christian Runge; Clemens Strohmaier; Andrea Trost; Birgit Tockner; Jeffrey W Kiel; Falk Schroedl; Herbert A Reitsamer Journal: Invest Ophthalmol Vis Sci Date: 2014-01-21 Impact factor: 4.799