May 2004
Volume 45, Issue 13
Free
ARVO Annual Meeting Abstract  |   May 2004
Practical Applications of Chromatic and Adaptation Dependent Receptoral–Interactions
Author Affiliations & Notes
  • A.J. Zele
    Optometry & Vision Sciences, University of Melbourne, Melbourne, Australia
  • A.J. Vingrys
    Optometry & Vision Sciences, University of Melbourne, Melbourne, Australia
  • Footnotes
    Commercial Relationships  A.J. Zele, Medmont Pty Ltd R; A.J. Vingrys, Medmont Pty Ltd F.
  • Footnotes
    Support  ARC–LP0211474
Investigative Ophthalmology & Visual Science May 2004, Vol.45, 4344. doi:
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      A.J. Zele, A.J. Vingrys; Practical Applications of Chromatic and Adaptation Dependent Receptoral–Interactions . Invest. Ophthalmol. Vis. Sci. 2004;45(13):4344.

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      © ARVO (1962-2015); The Authors (2016-present)

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Abstract

Abstract: : Purpose: To expose rod– and cone–interactions in achromatic and long–wavelength detecting mechanisms with a clinical paradigm. Methods: Thresholds were measured for coloured targets (0.43° diameter achromatic, λmax = 565nm; 0.86° diameter red, λmax = 660nm) across a range of eccentricities (0–10°) and adapting luminances (–3.0 to 1.6 log cd/sq.m; 1931xy: 0.33, 0.33). Temporal profiles were either static (increments, 200 ms) or flickering (12–18 Hz; 750 ms) with modulations about a mean adapting luminance (mean–modulated, MM) or shown on a concurrently displayed luminous increment (luminance–pedestal flicker, LP). Stimuli were generated on both a calibrated CRT controlled by a 12–bit graphics board (Bits++, CRS) and a modified perimeter (Medmont M700). All thresholds were estimated using an adaptive threshold algorithm (ZEST) on trichromatic and dichromatic (Protan, Deutan) observers. Results: Thresholds for achromatic targets (static and MM–flicker) seen on achromatic backgrounds follow classic cone dominated TvI functions at the fovea, with rod intrusion in the periphery. MM–flicker thresholds were lower than those for static probes. No interaction was observed for any long–wavelength target (static, MM–flicker and LP–flicker). In contrast, achromatic LP–flicker thresholds were elevated (∼2 log units) with respect to MM–flicker thresholds at dim background luminances (<–2.0 log cd/sq.m) and showed a secondary, but lesser threshold elevation (∼0.6 log units) that decreased at brighter light levels (0.0 log cd/sq.m). Conclusions: Receptor mediated interactions exposed by the luminance–pedestal flicker were dependent on background luminance, temporal frequency and target colour. Achromatic fields discouraged long–wavelength mediated receptor interactions that were observed with the same–on–same test and field condition. In particular, the achromatic LP–flicker elicited rod–cone interactions at dim light levels and, after rod saturation, unmasked cone–cone interactions. We show that receptoral dominated interactions (rod–cone and cone–cone) in perimetry can be generated by appropriate variation of stimulus parameters, exposing early disorders by challenging the adaptive process of a luminance mechanism.

Keywords: clinical research methodology • visual fields • temporal vision 
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