Concepts for automatic perimetry, as applied to the Scoperimeter, an experimental automatic perimeter.

The development of an experimental automatic perimeter, the Scoperimeter, is described. We use an oscilloscope as campimeter screen for the examination of the central 25 degrees of the visual field. The oscilloscope beam generates a homogeneous background luminance (0.1 cd/m2) and single stimulus static stimuli in any given position. The effective luminance-range of the stimuli is 3.0-3.5 log.unit. The visual field examination is controlled by a small computer system. Four examination programs written in Basic, are described. The screening programs using threshold related suprathreshold stimuli appear to be the most efficient compromise between speed and accuracy of the examination. The printout of these programs consists of a noninterpolated grey-scale presentation. Other programs perform static meridional perimetry or measure luminance threshold in 60 regularly distributed positions in the visual field. We have taken into consideration the factors that may influence the outcome of the examination: the presence of an instruction phase, the possibility to follow the progress of the examination and careful stimulus-timing. In a second paper we present clinical results we obtained using our instrument.