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Abstract #15418 Published in IGR 1-3
Effect of brimonidine on optic nerve blood flow in rabbits
Bhandari A; Cioffi GA; Van Buskirk EM; Orgül S; Wang LAmerican Journal of Ophthalmology 1999; 128: 601-605
PURPOSE: Brimonidine is a highly selective α2-adrenoreceptor agonist that lowers intraocular pressure (IOPs). The aim of the present study was to analyze in vivo the vasomotor effects and the influence of brimonidine on blood flow within the optic nerve, by means of intraluminal microvascular corrosion casting technique and intravascular injection of colored microspheres. METHODS: New Zealand white rabbits received either brimonidine tartrate 0.2% or placebo (vehicle) topical drops in one eye for four weeks. IOPs were measured at baseline and four weeks. The anterior optic nerve microvasculature of four rabbits was examined with corrosion castings for regions of focal vasoconstriction. Optic nerve blood flow was determined in 16 rabbits by means of nonradioactive color microspheres. RESULTS: The vasoconstriction values of the short posterior ciliary arterial branches in the brimonidine eyes were 16.7±3.7%. In the fellow untreated eyes, the mean vasoconstriction was 16.6±2.4%. In the placebo-treated eyes, the average constriction was 15.9±3.2%; the fellow eyes showed a mean constriction value of 16.1±5.3%. There was no statistical difference between any of the groups (p=0.02). The optic nerve blood flow in the brimonidine-treated rabbits was 0.18±0.06 ml/mg/min and 0.17±0.04 ml/mg/min in the treated and fellow eyes, respectively. Also, the difference between the optic nerve blood flow in the brimonidine-treated eyes and the optic nerve blood flow in all the untreated eyes (0.19±0.06 ml/mg/min) was not statistically different (p=0.82). CONCLUSIONS: Long-term application of brimonidine 0.2% does not affect the blood flow or vasomotor activity of the anterior optic nerve.
Dr. G.A. Cioffi, Discoveries in Sight, Devers Eye Institute, 1040 NW 22nd Avenue, Suite 200, Portland, OR 97210; USA
Classification:
6.11 Bloodflow measurements (Part of: 6 Clinical examination methods)
11.3.3 Apraclonidine, brimonidine (Part of: 11 Medical treatment > 11.3 Adrenergic drugs)
