RT Journal Article
T1 Rapid method for assessing rod function using recovery of spatial contrast thresholds following a bleach
A1 Puell Marín, María Cinta
A1 Kelly, Jeremiah M. F.
A1 Murray, Ian J.
AB Poor vision in low light is a common complaint of elderly people. This poorly understood phenomenon is likely to involve both receptoral and post receptoral mechanisms. We investigated the recovery of contrast thresholds for sine-wave gratings of low spatial frequencies and low mean luminance as a function of time in darkness after photo pigment bleaching. Thirteen subjects aged 30.4 (±10.7) years took part in the study. Contrast thresholds were measured for 15min following almost complete photo pigment bleaching. The stimuli were achromatic sinusoidal gratings of 0.5, 1 and 2 cycle per degree (cpd) generated on a CRT monitor. They had mean luminance 0.01cdm-2 and subtended 10° in diameter. The dynamics of the recovery at each spatial frequency were modelled using monophasic and biphasic exponential decay functions. The data were best modelled by a bi-phasic decay with a distinct transition point around 7min after the bleach. Both phases followed an exponential decay. The time constant (mean, standard error) for the first phase was 0.35 (0.04) minwhile for the second phase it was 5.15 (0.27) min. This difference was statistically significant (p<0.001). A control experiment revealed the second, slower phase was mediated by rod photoreceptors. Maximum contrast sensitivity was reached 15min after a photic bleach. The dynamics of contrast sensitivity recovery follow two phases and these may be attributed to the cone and rod systems.
PB Elsevier
SN 0014-4835
YR 2014
FD 2014-08
LK https://hdl.handle.net/20.500.14352/35375
UL https://hdl.handle.net/20.500.14352/35375
LA eng
NO Received 4 April 2014, Accepted 27 June 2014, Available online 9 July 2014
NO Ministerio de Educación
DS Docta Complutense
RD 8 abr 2025