Abstract

Central retinal vein occlusion (CRVO) is a disorder in which the circulation to the inner retina is impaired because of a blockage of the central retinal vein. The occlusion can produce severe inner retinal ischemia, leading in some patients to the blinding complication of neovascular glaucoma. In these patients, the choroidal circulation, which serves the photoreceptors, is not impaired. Several types of changes are seen in the electroretinogram (ERG) of patients with CRVO. Sabates and his associates¹ have reported preferential reductions in the b-wave amplitude relative to the a-wave amplitude in CRVO eyes that develop iris neovascularization. Johnson and co-workers² have measured ERG intensity-response functions in patients with CRVO and have analyzed the b-wave amplitudes by fitting the data with the Naka-Rushton function: (1) where I and R are intensity, response ordered pairs, R_max is the maximum b-wave amplitude (measured from the trough of the a-wave to the peak of the b-wave), K is the half-saturation constant (because when I = K, R = 1/2 R_max) and n is the slope. In normal observers, these parameters vary independently.³

© 1988 Optical Society of America