Photopigment optical density of the human foveola and a paradoxical senescent increase outside the fovea

Agnes B. Renner, Holger Knau, Maureen Neitz, Jay Neitz, John S Werner

Research output: Contribution to journalArticle

16 Scopus citations

Abstract

Photopigment optical density (OD) of middle-(M) and long-(L) wavelength-sensitive cones was determined to evaluate the hypothesis that reductions in the amount of photopigment are responsible for age-dependent sensitivity losses of the human cone pathways. Flicker thresholds were measured at the peak and tail of the photoreceptor's absorption spectrum as a function of the intensity of a bleaching background. Photopigment OD was measured at 0 (fovea), 2, 4, and 8 deg in the temporal retina by use of a 0.3-deg-diameter test spot. Seventy-two genetically characterized dichromats were studied so that the L- and M-cones could be analyzed separately. Subjects included 28 protanopes with M- but no L-cones and 44 deuteranopes with L- but no M-cones (all male, age range 12-29 and 55-83 years). Previous methods have not provided estimates of photopigment OD for separate cone classes in the foveola. In this study, it was found that foveolar cones are remarkably efficient, absorbing 78% of the available photons (OD = 0.65). Photopigment OD decreased exponentially with retinal eccentricity independently of age and cone type. Paradoxically, the OD of perifoveal cones increased significantly with age. Over the 70-year age range of our participants, the perifoveal M- and L-cones showed a 14% increase in capacity to absorb photons despite a 30% decrease in visual sensitivity over the same period.

Original languageEnglish (US)
Pages (from-to)827-834
Number of pages8
JournalVisual Neuroscience
Volume21
Issue number6
DOIs
StatePublished - Nov 2004

Keywords

  • Aging
  • Color blindness
  • Cones
  • Dichromacy
  • Photopigment optical density

ASJC Scopus subject areas

  • Neuroscience(all)

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