Abstract
The relationship between ciliary perfusion and aqueous production is poorly understood. It was recently reported that aqueous production decreases when ciliary blood flow is reduced by lowering the ocular perfusion pressure, and hypothesized that drug-induced reduction of ciliary blood flow would also decrease aqueous production. In the present study, we test this hypothesis with an α2 adrenergic agonist (brimonidine) formulated for topical application. When used acutely, brimonidine decreases intraocular pressure (IOP) by suppressing aqueous production, although its mechanism of action is unclear. The experiments were performed in four groups of anesthetized rabbits (n=33) in which the following variables were measured: ocular mean arterial pressure (OMAP), IOP, orbital venous pressure (OVP), aqueous flow, ciliary blood flow, ciliary oxygen tension (PO2), episcleral venous pressure (EVP), carotid blood flow and heart rate. The measurements were made before and after brimonidine (0.15%, 40 μl) was applied to the cornea. Brimonidine decreased IOP (-33%, p<0.01), aqueous flow (-39%, p<0.01), ciliary blood flow (-37%, p<0.01), EVP (-42%, p<0.01) and ciliary PO2 (-32%, p<0.05). We conclude that topical brimonidine is a ciliary vasoconstrictor, and that α2 adrenergic agonist-induced decreases in ciliary blood flow decrease aqueous production.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 405-415 |
| Number of pages | 11 |
| Journal | Experimental Eye Research |
| Volume | 82 |
| Issue number | 3 |
| DOIs | |
| State | Published - Mar 2006 |
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Keywords
- Brimonidine
- Episcleral venous pressure
- Intraocular pressure homeostasis
- Ocular hydrodynamics
- Oxygen
ASJC Scopus subject areas
- Ophthalmology
- Sensory Systems
Cite this
Effects of a topical α2 adrenergic agonist on ciliary blood flow and aqueous production in rabbits. / Reitsamer, H. A.; Posey, M.; Kiel, J. W.
In: Experimental Eye Research, Vol. 82, No. 3, 03.2006, p. 405-415.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Effects of a topical α2 adrenergic agonist on ciliary blood flow and aqueous production in rabbits
AU - Reitsamer, H. A.
AU - Posey, M.
AU - Kiel, J. W.
PY - 2006/3
Y1 - 2006/3
N2 - The relationship between ciliary perfusion and aqueous production is poorly understood. It was recently reported that aqueous production decreases when ciliary blood flow is reduced by lowering the ocular perfusion pressure, and hypothesized that drug-induced reduction of ciliary blood flow would also decrease aqueous production. In the present study, we test this hypothesis with an α2 adrenergic agonist (brimonidine) formulated for topical application. When used acutely, brimonidine decreases intraocular pressure (IOP) by suppressing aqueous production, although its mechanism of action is unclear. The experiments were performed in four groups of anesthetized rabbits (n=33) in which the following variables were measured: ocular mean arterial pressure (OMAP), IOP, orbital venous pressure (OVP), aqueous flow, ciliary blood flow, ciliary oxygen tension (PO2), episcleral venous pressure (EVP), carotid blood flow and heart rate. The measurements were made before and after brimonidine (0.15%, 40 μl) was applied to the cornea. Brimonidine decreased IOP (-33%, p<0.01), aqueous flow (-39%, p<0.01), ciliary blood flow (-37%, p<0.01), EVP (-42%, p<0.01) and ciliary PO2 (-32%, p<0.05). We conclude that topical brimonidine is a ciliary vasoconstrictor, and that α2 adrenergic agonist-induced decreases in ciliary blood flow decrease aqueous production.
AB - The relationship between ciliary perfusion and aqueous production is poorly understood. It was recently reported that aqueous production decreases when ciliary blood flow is reduced by lowering the ocular perfusion pressure, and hypothesized that drug-induced reduction of ciliary blood flow would also decrease aqueous production. In the present study, we test this hypothesis with an α2 adrenergic agonist (brimonidine) formulated for topical application. When used acutely, brimonidine decreases intraocular pressure (IOP) by suppressing aqueous production, although its mechanism of action is unclear. The experiments were performed in four groups of anesthetized rabbits (n=33) in which the following variables were measured: ocular mean arterial pressure (OMAP), IOP, orbital venous pressure (OVP), aqueous flow, ciliary blood flow, ciliary oxygen tension (PO2), episcleral venous pressure (EVP), carotid blood flow and heart rate. The measurements were made before and after brimonidine (0.15%, 40 μl) was applied to the cornea. Brimonidine decreased IOP (-33%, p<0.01), aqueous flow (-39%, p<0.01), ciliary blood flow (-37%, p<0.01), EVP (-42%, p<0.01) and ciliary PO2 (-32%, p<0.05). We conclude that topical brimonidine is a ciliary vasoconstrictor, and that α2 adrenergic agonist-induced decreases in ciliary blood flow decrease aqueous production.
KW - Brimonidine
KW - Episcleral venous pressure
KW - Intraocular pressure homeostasis
KW - Ocular hydrodynamics
KW - Oxygen
UR - http://www.scopus.com/inward/record.url?scp=31344463531&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=31344463531&partnerID=8YFLogxK
U2 - 10.1016/j.exer.2005.07.015
DO - 10.1016/j.exer.2005.07.015
M3 - Article
C2 - 16198336
AN - SCOPUS:31344463531
VL - 82
SP - 405
EP - 415
JO - Experimental Eye Research
JF - Experimental Eye Research
SN - 0014-4835
IS - 3
ER -