Pattern electroretinogram as a function of spatial frequency after retrobulbar optic neuritis.
Steady-state (8-Hz) pattern electroretinograms in response to counterphased sinusoidal gratings of variable spatial frequency (0.6-4.8 c/deg) were recorded in 17 patients who had had retrobulbar optic neuritis in one or both eyes (23 eyes with a clinical history of optic neuritis) and in 21 age-matched normal subjects. Amplitude and phase of the Fourier-analyzed pattern electroretinogram second harmonic were measured. The mean pattern electroretinogram amplitude of patients was significantly reduced compared with that of controls. Amplitude reductions were more marked at intermediate (1-1.4 c/deg) than at lower or higher spatial frequencies. Therefore, the average amplitude versus spatial frequency response function differed significantly in patients compared with controls, displaying a lowpass instead of a band-pass shape. No significant differences in the mean pattern electroretinogram phase were observed between groups at any spatial frequency. These results indicate spatial frequency-dependent abnormalities in the pattern electroretinogram amplitude after optic neuritis, suggesting a specific loss of retinal neurons sensitive to stimuli of intermediate spatial frequencies.
Falsini
B
B
Eye Clinic, Catholic University, Rome, Italy.
Bardocci
A
A
Cermola
S
S
Porciatti
V
V
Porrello
G
G
D000328:Adult; D002648:Child; D004596:Electroretinography; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009902:Optic Neuritis / Q000503:physiopathology*; D009915:Orbit; D010364:Pattern Recognition, Visual; D012160:Retina / Q000503:physiopathology*; D014792:Visual Acuity; D014794:Visual Fields