Age-related increases in photopic increment thresholds are not due to an elevation in intrinsic noise

John S Werner, Kathy A. Schelble, Michelle L. Bieber

Research output: Contribution to journalArticle

7 Scopus citations

Abstract

Threshold vs. intensity (tvi) functions were measured under conditions in which the slope of the rising branch approximated the deVries-Rose law in order to evaluate the contribution of intrinsic visual noise (dark light, Eigengrau) to age-related elevations in threshold under photopic conditions. Data were obtained from 48 observers (20-88 years) using a temporal 2AFC procedure. The stimulus was centered at 8° nasal retinal eccentricity and consisted of a 560 nm, 14.4′ test flash (10 ms) concentric with a steady 500 nm (12.9°) adapting field (13 intensity levels ranging from 0-9 log quanta · sec-1 · deg-2), which resulted in clear scotopic and photopic branches. Photopic thresholds increased linearly with age at a rate of 0.08 log unit per decade at the cornea. The mean slope of the rising portion of the tvi functions (in log-log coordinates) was 0.62, and not correlated with age. Dark light values increased with age, but not significantly. Dark light was a statistically significant predictor of individual differences in absolute photopic threshold, but it is not responsible for age-related increases in threshold under photopic conditions.

Original languageEnglish (US)
JournalColor Research and Application
Volume26
Issue numberSUPPL.
StatePublished - 2001

Keywords

  • Aging
  • Cone sensitivity
  • Dark light
  • Increment thresholds
  • Individual differences
  • Noise
  • Photopic sensitivity
  • Thresholds

ASJC Scopus subject areas

  • Chemical Engineering(all)

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