Automated perimetry with bright and dark stimuli

Conventional perimeters use bright stimuli. In this study, dark stimuli were also used. Dark stimuli are employed for testing due to their lack of effects of local scatter and are utilized with the purpose of preferentially stimulating the off-system, but their presentation with optical methods is difficult. This problem is solved by the use of a computer monitor. The objective of this study was to compare directly measurements obtained with bright and dark stimuli. Therefore, the central 30 degrees of the visual field of ten subjects with no ophthalmologic pathology was examined with bright and dark stimuli (size 10- and 30-min-of-arc). Threshold estimation was performed with the 4/2 method. Concerning the 10-min-of-arc dark stimulus, no measurement outside the central 15 degrees could be performed because of insufficient dynamic range (sometimes even the darkest stimulus was not seen). Comparing the results obtained using bright and dark stimuli of the same size, we could not find a significant difference in sensitivity for this age group.