Clinical application of time-dependent perimetry: 1. Results in normal subjects.

A perimeter was constructed, using red light-emitting diodes by remodeling a Foerster's perimeter, to test three time-dependent visual functions, ie, double flash resolution (DFR), which is the time threshold of double flash separation, critical flicker fusion frequency (CFF), which is the threshold of flicker separation and perceptual delay (PD), which is the difference in perception between two locations of the visual field. In 10 normal subjects, the DFR and CFF were determined in the center of the field and in 12 points in the paracentral field 10 degrees away from the center. The CFF value was lower in the center than in the paracentral field where no significant difference was found among various meridians. The DFR values showed a marked individual variation. The value was significantly higher in the upper and lower paracentral fields than in the nasal and temporal fields: the DFR in the center of the field showed no significant difference from the DFR in the nasal and temporal paracentral field. The PD was determined between the center and paracentral fields. Individual variation was small and no significant difference was found among the paracentral fields. These results in normal subjects offer a reference for clinical application of the present test methods for various diseases.