The Effect of Adenosine on Optic Nerve Head Blood Flow and Oxygen Tension in the Rabbit Eye

Abstract

 

Purpose:

 

To investigate the effect of intravenous adenosine on optic nerve head circulation and optic nerve head oxygenation in rabbits.

 

Methods:

 

In anesthetized New Zealand rabbits (n=24) mean arterial pressure (MAP) and intraocular pressure (IOP) were measured by direct cannulation of the central ear artery and the vitreous respectively. Laser Doppler flowmetry was used to measure the blood flow in the optic nerve head. Oxygen concentration at the optic disc (ONH O2) was measured with a 0,2 mm vitreal fibreroptic fluorescent probe (Oxford Optronix) Adenosine was applied intravenously at an infusion rate of 5mg/h/kg.

 

Results:

 

Adenosine significantly increased IOP, optic nerve head blood flow, ONH O2 and heart rate (HR) whereas optic nerve head vascular resistance (R) decreased (see table). Furthermore adenosine caused a significant increase in pre-optic nerve head- oxygenation.  

 

Conclusions:

 

Adenosine causes vasodilation in the optic nerve vascular bed accompanied by an increase in oxygen tension in the pre-optic nerve head vitreous.

 

Keywords: adenosine • optic disc • blood supply