A new method for oxygen supply to acute ischemic retina.

This paper introduces a new method for supplying oxygen directly to ischemic inner retina, using an oxygen source in the vitreous. Acute retinal vascular occlusion was created in cat eyes by direct pressure on the optic disk and its margins with a glass probe. The satisfactory occlusion of the retinal vessels was documented by direct observation, and functionally by recording the ERG. The vascular occlusion caused a large decrease in the size of the ERG b wave, with no change in the a wave amplitude. The oxygen source was a catheter made of strands of an oxygen-permeable membrane which was inserted into the vitreal cavity. After successful vascular occlusion was documented, 100% gaseous oxygen was perfused through the catheter while recording the ERG. In response to the perfused oxygen the b wave partially recovered. Ventilating the animal with 100% oxygen when the retinal vessels were occluded also caused recovery of the b wave amplitude. Termination of the vitreal oxygen source caused a decrease in b wave amplitude to the level previously observed after the occlusion of the retinal vessels. When the retinal circulation was restored by removal of the glass probe the b wave recovered. The results show that it is possible to supply adequate oxygen to the inner retina via the vitreous to replace the oxygen normally supplied by the retinal circulation. Modification of this method may be useful for the treatment of recent and incomplete retinal vascular occlusion.