CONTRAST AND LUMINANCE AS PARAMETERS DEFINING THE OUTPUT OF THE VERISTOPOGRAPHICAL ERG

The Visual Evoked Response Imaging System (VERIS I) topographical elec troretinogram system (EDI Associates, San Francisco, CA) allows measur ement of the response of large numbers of retinal areas simultaneously . This paper examines ERG responses derived with the VERIS system to c hanges in target contrast and to local reductions in luminance. There is a linear reduction of response with reductions of target contrast. Neutral density filters were placed over part of the display, to mimic the localised reductions in response which occur in glaucoma, age-rel ated maculopathy or diabetic retinopathy. There is a definite reductio n in response seen with a 0.4 ND filter, indicating that the system sh ould have similar sensitivity in detection of retinal lesions to the c ommonly used visual field analysis systems.