The influences of stimulus wavelength and eccentricity on short-wavelengthpathway isolation in automated perimetry

The aim of the study was to determine whether the suggested stimulus and ba ckground parameters employed in commercially available short-wavelength sen sitive perimetry (SWAP) are clinically appropriate. Threshold versus intens ity curves were measured using a modified Humphrey Field Analyser. The redu ction in background luminance was achieved using aperture stops in order to avoid changes in the chromaticity of the background. Short-wavelength thre sholds were determined for 440, 450 and 460 nm stimuli and were corrected f or pre-receptoral absorption. Short-wavelength sensitive pathway isolation was approximately 1.5 log units and decreased with increases in eccentricit y and in stimulus wavelength. It would seem that the use of a 450 nm narrow band stimulus filter would offer a compromise between both the physiologica l requirements and the physical properties of the stimulus. Such an approac h would reduce some of the inherent between-subject normal variability asso ciated with SWAP. (C) 2000 The College of Optometrists. Published by Elsevi er Science Ltd. All rights reserved.