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Abstract #9682 Published in IGR 5-3
Relationship between ciliary blood flow and aqueous production in rabbits
Reitsamer HA; Kiel JWInvestigative Ophthalmology and Visual Science 2003; 44: 3967-3971
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 mmHg and for an additional 60 minutes at target MAPs of 80, 55, or 40 mmHg. 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 mmHg. 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.
Dr. H.A. Reitsamer, Department of Physiology, University of Vienna Medical School, Vienna, Austria. herbert.reitsamer@univie.ac.at
Classification:
2.6.1 Production (Part of: 2 Anatomical structures in glaucoma > 2.6 Aqueous humor dynamics)
2.9 Ciliary body (Part of: 2 Anatomical structures in glaucoma)
6.11 Bloodflow measurements (Part of: 6 Clinical examination methods)
