Abstract
We investigated the effect of topical betaxolol on impaired choroidal blood flow (CBF) induced by endothelin-1 (ET-1) injection into the vitreous of albino rabbits. Betaxolol (n = 7) or balanced salt solution (BSS) (n = 6) was instilled in the right eyes before and 12 hrs after the intravitreal injection of ET-1 (10-6 M, 10 μl), and BSS was instilled in the right eyes before and 12 hrs after the intravitreal injection of BSS (n = 6). Blood pressure, intraocular pressure and CBF were measured prior to the instillation of betaxolol or BSS, and just before and 2 hrs, 12 hrs and 24 hrs after ET-1 or BSS injection. CBF was measured by scanning laser Doppler flowmetry.
Intravitreal injection of ET-1 decreased CBF. Compared with topical BSS, topical betaxolol significantly inhibited the decrease in CBF at 2 hrs (p = .022), 12 hrs (p = .046) and 24 hrs (p = .015) after the intravitreal injection of ET-1. There was no significant change of blood pressure or intraocular pressure after the topical administration of betaxolol or the intravitreal injection of ET-1. The decrease in CBF after the intravitreal injection of ET-1 was partially inhibited by topical betaxolol.
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