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Adaptation Mechanisms, Eccentricity Profiles, and Clinical Implementation of Red-on-White Perimetry.

Zele AJ, Dang TM, O'Loughlin RK, Guymer RH, Harper A, Vingrys AJ

Department of Optometry and Vision Sciences, The University of Melbourne, Victoria, Australia (AJZ, TMD, RKO, AJV), School of Optometry and the Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane, Queensland, Australia (AJZ), and Centre for Eye Research Australia, The University of Melbourne, East Melbourne, Victoria, Australia (RHG, AH).

PURPOSE.: To determine the visual adaptation and retinal eccentricity profiles for red flickering and static test stimuli and report a clinical implementation of these stimuli in visual perimetry. METHODS.: The adaptation profile for red-on-white perimetry stimuli was measured using a threshold vs. intensity (TvI) paradigm at 0 degree and 12 degrees eccentricity and by comparing the eccentricity-related sensitivity change for red and white, static, and flickering targets in young normal trichromats (n = 5) and a group of dichromats (n = 5). A group of older normal control observers (n = 30) were tested and retinal disease was evaluated in persons having age-related maculopathy (n = 35) and diabetes (n = 12). RESULTS.: Adaptation and eccentricity profiles indicate red static and flickering targets are detected by two mechanisms in the paramacular region, and a single mechanism for >5 degrees eccentricity. The group data for the older normal observers has a high level of inter-observer variability with a generalized reduction in sensitivity across the entire visual field. Group data for the participants with age-related maculopathy show reduced sensitivities that were pronounced in the central retina. The group data for the diabetic observers showed sensitivities that were reduced at all eccentricities. The disease-related sensitivity decline was more apparent with red than white stimuli. CONCLUSIONS.: The adaptation profile and change in sensitivity with retinal eccentricity for the red-on-white perimetric stimuli are consistent with two detection processes. In the macula, the putative detection mechanism is color-opponent with static targets and non-opponent with flickering targets. At peripheral field locations, the putative detection mechanism is non-opponent for both static and flicker targets. The long-wavelength stimuli are less affected by the preretinal absorption common to aging. Red-on-white static and flicker perimetry may be useful for monitoring retinal disease, revealing greater abnormalities compared with conventional white-on-white perimetry, especially in the macula where two detection mechanisms are found.

Published 8 May 2008 in Optom Vis Sci, 85(5): 309-317.
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