Normal Threshold Values for Red Targets in the Central 10 Degree Visual Field

Josephine Piraino BappSc(Syd)
Helen Goodacre MHlthScEd(Syd) DipAppSc(Cumb)

Automated Perimetry is widely used in ophthalmic practices to monitor changes in a patient’s visual field. White stimuli are usually used and sophisticated statistical analysis is obtained comparing the patient’s data to normal age matched results. Red stimuli can be used to monitor early effects of drugs in the visual field yet no comparative data is available.
The central visual field was examined with a 10-2 visual programme on the Humphrey Visual Field Analyser using red and white targets to establish normal perimetic data for red fields.
Red and white fields for 53 subjects (70 eyes) were obtained, age range 15-57 years. The fields were analysed using quadrant totals of decibel (db) threshold values. Then totals for superior and inferior fields, as well as nasal and temporal fields and then the whole fields were calculated. The decibel values were significantly reduced when the red thresholds were compared with white thresholds irrespective of the area of field tested. The means and standard deviations of each test location were calculated for the red fields. It was found that the visual threshold for red fields with the 10-2 program ranged from 21.1 dB with standard deviation + 1.73dB peripherally, to 26.6 dB with standard deviation + 1.83dB centrally. Three of the seventy eyes examined showed significant field defects (both clinically and statistically) when tested with the red target compared to a normal field with the white target.