A versatile system for studying mammalian intraretinal metabolism and function in situ

Abstract

Microelectrodes can be introduced into the intact mammalian eye after the preparation has been stabilized with an animal head-holder and an ocular fixation ring. A versatile system for introduction and manipulation of the electrode consists generally of three coaxially orientated tube-like structures which interadapt in a telescopic fashion: an illuminator is threaded into the main body of a micromanipulator, the electrode, in turn, is threaded into the illuminator. The whole central axis therefore moves in unison as the micromanipulator is positioned or advanced by a remotely controlled hydraulic motion operating system. Two drive jacks, angularly attached to the main body, can move the central axis within a 38° conical plane around the vertical axis. Intravitreal and transretinal vertical movements (down to 2 μm) can be executed by coarse and fine controls respectively. The illuminator is used for intravitreal, fundic and electrode illumination as well as photo-stimulation (for electroretinography). PO 2 and pH microelectrodes have been successfully used in this system. Local electroretinograms can be made using the PO 2 electrode as the sensor. Simultaneous transretinal PO 2 measurements and electroretinography are theoretically possible using a single PO 2 electrode. Microelectrode measurements are generally made in a specially designed Faraday cage.