Human scotopic dark adaptation: Comparison of recoveries of psychophysical threshold and ERG b-wave sensitivity.

We have compared the time course of dark adaptation of the human scotopic visual system, measured psychophysically and from the b-wave of the electroretinogram (ERG), for bleaches ranging from a few percent to near total. We also measured light adaptation, in order to apply a "Crawford transformation" to convert the raw measurements of dark adaptation into equivalent background intensities. For both the "psychophysical threshold equivalent" intensity and the "ERG b-wave sensitivity equivalent" intensity, the equivalent background declined over much of its range with an "S2" component, though with somewhat different slopes of -0.36 (psychophysical) and -0.22 (ERG) log(10) unit min(-1), respectively. In addition, the magnitude of the equivalent background was approximately 1 log(10) unit lower in the psychophysical experiments than in the ERG experiments. Despite these differences, the two approaches extract a common time course for the decline in level of free opsin following moderately large bleaches. We conclude that the recovery of psychophysical scotopic visual threshold over the S2 region reflects events that are present by the stage of the first synapse of rod vision, stemming ultimately from the presence of unregenerated opsin in the rod outer segments.

[1]  W Seiple,et al.  Multifocal rod electroretinograms. , 1998, Investigative ophthalmology & visual science.

[2]  Maureen K. Powers,et al.  Mechanisms of light adaptation in rat retina , 1982, Vision Research.

[3]  T. Lamb,et al.  Dark adaptation recovery of human rod bipolar cell response kinetics estimated from scotopic b‐wave measurements , 2008, The Journal of physiology.

[4]  T. Lamb,et al.  Effect of hydroxylamine on photon‐like events during dark adaptation in toad rod photoreceptors , 1997, The Journal of physiology.

[5]  Cynthia Owsley,et al.  Aging and dark adaptation , 1999, Vision Research.

[6]  A. J. Roman,et al.  Quantifying rod photoreceptor-mediated vision in retinal degenerations: dark-adapted thresholds as outcome measures. , 2005, Experimental eye research.

[7]  B. Sakitt Counting every quantum , 1972, The Journal of physiology.

[8]  B. H. Crawford Visual adaptation in relation to brief conditioning stimuli , 1947, Proceedings of the Royal Society of London. Series A. Mathematical and Physical Sciences.

[9]  J. Robson,et al.  Effects of background light on the human dark-adapted electroretinogram and psychophysical threshold. , 1996, Journal of the Optical Society of America. A, Optics, image science, and vision.

[10]  T. Lamb,et al.  Dark adaptation and the retinoid cycle of vision , 2004, Progress in Retinal and Eye Research.

[11]  T. Lamb,et al.  Recovery of the human photopic electroretinogram after bleaching exposures: estimation of pigment regeneration kinetics , 2004, The Journal of physiology.

[12]  S. Hecht,et al.  ENERGY, QUANTA, AND VISION , 1942, The Journal of general physiology.

[13]  William Albert Hugh Rushton,et al.  The Ferrier Lecture, 1962 Visual adaptation , 1965, Proceedings of the Royal Society of London. Series B. Biological Sciences.

[14]  H. Barlow Dark and Light Adaptation: Psychophysics , 1972 .

[15]  E N Pugh,et al.  Rushton's paradox: rod dark adaptation after flash photolysis. , 1975, The Journal of physiology.

[16]  T. Lamb,et al.  Dark adaptation of toad rod photoreceptors following small bleaches , 1994, Vision Research.

[17]  V. Sheffield,et al.  Night blindness in Sorsby's fundus dystrophy reversed by vitamin A , 1995, Nature Genetics.

[18]  T. Aleman,et al.  Rod and cone visual cycle consequences of a null mutation in the 11-cis-retinol dehydrogenase gene in man , 2000, Visual Neuroscience.

[19]  T. Lamb,et al.  Rod plateaux during dark adaptation in Sorsby's fundus dystrophy and vitamin A deficiency. , 1997, Investigative ophthalmology & visual science.

[20]  R. Carr,et al.  Local cone and rod system function in patients with retinitis pigmentosa. , 2001, Investigative ophthalmology & visual science.

[21]  C. M. Kemp,et al.  Photoreceptor function in heterozygotes with insertion or deletion mutations in the RDS gene. , 1996, Investigative ophthalmology & visual science.

[22]  G. R. Jackson,et al.  Delays in rod-mediated dark adaptation in early age-related maculopathy. , 2001, Ophthalmology.

[23]  T. Lamb,et al.  The involvement of rod photoreceptors in dark adaptation , 1981, Vision Research.

[24]  M. Cornwall,et al.  Bleached pigment activates transduction in isolated rods of the salamander retina. , 1994, The Journal of physiology.

[25]  K. Nordby,et al.  Dark-adaptation of the human rod system , 1984, Vision Research.

[26]  S. Hecht,et al.  THE INFLUENCE OF LIGHT ADAPTATION ON SUBSEQUENT DARK ADAPTATION OF THE EYE , 1937, The Journal of general physiology.

[27]  T. Lamb,et al.  Light adaptation and dark adaptation of human rod photoreceptors measured from the a‐wave of the electroretinogram , 1999, The Journal of physiology.

[28]  Michael Kalloniatis,et al.  Characterisation of dark adaptation in human cone pathways: an application of the equivalent background hypothesis , 2000, The Journal of physiology.

[29]  S. Jacobson,et al.  Automated light- and dark-adapted perimetry for evaluating retinitis pigmentosa. , 1986, Ophthalmology.

[30]  C. Cowan,et al.  A comparison of the efficiency of G protein activation by ligand-free and light-activated forms of rhodopsin. , 1997, Biophysical journal.

[31]  W A Rushton,et al.  Dark adaptation and increment threshold in a rod monochromat. , 1965, The Journal of physiology.

[32]  T. Lamb,et al.  Dark adaptation of human rod bipolar cells measured from the b‐wave of the scotopic electroretinogram , 2006, The Journal of physiology.

[33]  H. Barlow Temporal and spatial summation in human vision at different background intensities , 1958, The Journal of physiology.