The influences of stimulus wavelength and eccentricity on short-wavelength pathway isolation in automated perimetry.
The aim of the study was to determine whether the suggested stimulus and background parameters employed in commercially available short-wavelength sensitive perimetry (SWAP) are clinically appropriate. Threshold versus intensity curves were measured using a modified Humphrey Field Analyser. The reduction in background luminance was achieved using aperture stops in order to avoid changes in the chromaticity of the background. Short-wavelength thresholds were determined for 440, 450 and 460 nm stimuli and were corrected for pre-receptoral absorption. Short-wavelength sensitive pathway isolation was approximately 1.5 log units and decreased with increases in eccentricity and in stimulus wavelength. It would seem that the use of a 450 nm narrowband stimulus filter would offer a compromise between both the physiological requirements and the physical properties of the stimulus. Such an approach would reduce some of the inherent between-subject normal variability associated with SWAP.
Cubbidge
R P
RP
Vision Sciences Research Institute, School of Life and Health Sciences, Aston University, Aston Triangle, Birmingham B4 7ET, UK.
Wild
J M
JM
D000328:Adult; D001331:Automation; D006801:Humans; D010775:Photic Stimulation; D012684:Sensory Thresholds / Q000502:physiology*; D058609:Visual Field Tests / Q000295:instrumentation / Q000592:standards*