Effects of using the oxygen-carrying fluorocarbon, FC43, on the ERG of the arterially perfused cat eye

Abstract

Arterial perfusion of the isolated cat eye with a perfusate augmented with a 20% (wt/vol) emulsion of the oxygen carrying-fluorocarbon, FC43, produces a much larger b-wave in the electroretinogram than use of the same perfusate lacking FC43. The c-wave is either unchanged or slightly reduced by use of this solution. Halving the oxygen content of the FC43-augmented perfusate also reversibly reduces the b-wave. The use of perfusates with and without FC43 but containing similar amounts of oxygen produces b-waves of similar amplitude. The large b-wave recorded during use of a well-oxygenated, FC43-augmented perfusate suggests that the use of perfusates containing less oxygen produces retinal hypoxia. The b-wave recorded in vivo is considerably smaller than that recorded from the isolated eye during perfusion with a well-oxygenated, FC43-augmented perfusate, but the waveforms are very similar. In particular, the ratios of the b-wave to a-wave are almost identical. The larger ERG recorded in vitro is a result of increasing the shunt resistance to ground upon enucleation. Histological examination of retinas perfused for two hours with the FC43-augmented and standard perfusate reveal no clear signs of tissue hypoxia in either retina. However, even two hours of complete ischemia produces limited inner retinal deterioration and virtually no outer retinal damage, suggesting that the histological state of the retina may not be a reliable indicator of its physiological state. Despite the improved electrophysiological state of the retina produced by increasing its oxygen supply, the survival time of the isolated eye was not increased.