[Detection of retinal visual field defects by sectorial photic stimulation in scotopic luminance ERG]

We developed an electroretinographic procedure to assess visual field defects due to dysfunction of the outer retinal layers. For this objective we determined the amplitude/intensity function of the scotopic b-wave to full field (100 degrees of visual angle), quadrant and hemifield stimulation in 14 healthy volunteers and in patients with visual field disturbances. To prevent stray light effects, we confined the test light illuminance to 10(1.3) of the extrapolated normal ERG threshold (about 10(4.2) the sensory dark threshold). Whereas patients with dysfunction of the proximal retinal layers or the optic nerve did not show any change when the corresponding visual field was stimulated, those suffering from disturbances of the distal retinal layers (e.g., amotio, chorioretinal diseases) showed a reduction in the amplitude/intensity function, which was related to the extension and the degree of the field losses. The method reveals visual field defects caused by disturbances in the outer retinal layers where one-fourth or more of the corresponding retinal quadrant exhibits a sensitivity loss of more than 15 dB.