Electrophysiology in pseudohistoplasmosis and chronic idiopathic retinal vasculitis

We used computerized electroretinography (E.R.G.) flash to study 12 patients: five pseudohistoplasmosis (P.S.H.) and seven chronic idiopathic retinal vasculitis (C.I.R.V.), compared with 12 healthy controls. We found a moderate correlation in controls between white computer averaged b-wave amplitude and b-wave obtained with other wavelengths (over 600 nm red, over 550 nm orange, and under 500 nm blue), in scotopic (white/orange r = 0.41, P < 0.05; white/red r = 0.45, P < 0.05; white/blue r = 0.48, P < 0.02) and photopic conditions (white/orange r = 0.6, P < 0.01). For P.S.H. there was a highly significant correlation between white and all wavelengths in photopic (white/orange r = 1, white/red r = 0.96, P < 0.0001) and scotopic conditions (white/orange r = 0.97, P < 0.0001; white/red r = 0.96, P < 0.0001; white/blue r = 0.96). In vasculitis, as in controls, we found no white/red correlation and only in vasculitis we could not find a scotopic white/blue correlation. We conclude that these situations are electrophysiologically different. The closer correlation in P.S.H. suggests more efficient phototransduction and in C.I.R.V. there may also be a rod-selective dysfunction.