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Abstract #23935 Published in IGR 11-2
Effects of dorzolamide on choroidal blood flow, ciliary blood flow, and aqueous production in rabbits
Reitsamer HA; Bogner B; Tockner B; Kiel JWInvestigative Ophthalmology and Visual Science 2009; 50: 2301-2307
PURPOSE: To determine the effects of topical dorzolamide (a carbonic anhydrase inhibitor) on choroidal and ciliary blood flow and the relationship between ciliary blood flow and aqueous flow. METHODS: The experiments were performed in four groups of pentobarbital-anesthetized rabbits treated with topical dorzolamide (2%, 50 microL). In all groups, intraocular pressure (IOP) and mean arterial pressure (MAP) at the eye level were measured continuously by direct cannulation. In group 1, aqueous flow was measured by fluorophotometry before and after dorzolamide treatment. In group 2, aqueous flow was measured after dorzolamide at normal MAP and while MAP was held constant at 80, 55, or 40 mm Hg with occluders on the aorta and vena cava. In group 3, the same MAP levels were used, and ciliary blood flow was measured transsclerally by laser Doppler flowmetry (LDF). In group 4, choroidal blood flow was measured by LDF with the probe tip positioned in the vitreous over the posterior pole during ramp increases and decreases in MAP before and after dorzolamide. RESULTS: Dorzolamide lowered IOP by 19% (P < 0.01) and aqueous flow by 17% (P < 0.01), and increased ciliary blood flow by 18% (P < 0.01), which was associated with a significant reduction in ciliary vasculature resistance (-7%, P < 0.01). Dorzolamide shifted the relationship between ciliary blood flow and aqueous flow downward relative to the previously determined control relationship in the rabbit. Dorzolamide did not alter choroidal blood flow, choroidal vascular resistance, or the choroidal pressure flow relationship. CONCLUSIONS: Acute topical dorzolamide is a ciliary vasodilator and has a direct inhibitory effect on aqueous production, but it does not have a detectable effect on choroidal hemodynamics at the posterior pole in the rabbit.
Department of Ophthalmology and Optometry, Paracelsus Medical University, Salzburg, Austria. h.reitsamer@salk.at
Classification:
11.5.2 Topical (Part of: 11 Medical treatment > 11.5 Carbonic anhydrase inhibitors)
2.6.1 Production (Part of: 2 Anatomical structures in glaucoma > 2.6 Aqueous humor dynamics)
6.11 Bloodflow measurements (Part of: 6 Clinical examination methods)
5.3 Other (Part of: 5 Experimental glaucoma; animal models)
