Ripamonti, C;
Aboshiha, J;
Henning, B;
Sergouniotis, PI;
Michaelides, M;
Moore, AT;
Webster, AR;
(2014)
Vision in observers with enhanced S-cone syndrome: an excess of S-cones connected mainly to conventional S-cone pathways but also a faster pathway.
Investigative Ophthalmology & Visual Science
, 55
(2)
pp. 963-976.
10.1167/iovs.13-12897.
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Abstract
Purpose: The effect of increased numbers of S-cone photoreceptors in enhanced S-cone syndrome (ESCS) was investigated psychophysically in six ESCS observers to understand more about the relative cone sensitivities and postreceptoral organization. Methods: Measures of temporal sensitivity or delay were made: S- and L-cone temporal acuity (critical flicker fusion or cff), S-cone temporal contrast sensitivity, and S-cone delay. Results: ESCS observers showed uniform enhancements of S-cone cff of between 0.85 and 6.25 Hz, but reductions in L-cone cff. They also showed higher S-cone temporal-contrast-sensitivities at medium and high S-cone adaptation levels with sensitivity functions that peaked near 7.5 Hz but fell off at lower and higher frequencies; in contrast, the mean normal function was flat at low frequencies and fell-off only at high frequencies. The S-cone signal, as in the normal, is subject to large phase delays. Conclusions: We interpret the enhancements in cff as increases in S-cone number in ESCS of between 1.39 and 11.32 times normal density (with a mean of 3.48). The peaked ESCS contrast-sensitivity functions are consistent with S-cone signal interactions that increase sensitivity at intermediate frequencies through constructive interference but decrease it at lower and higher frequencies through destructive interference. Measures of S-cone delays relative to L- and M-cone signals show that the predominant S-cone signals in ESCS are negative and delayed as in normal observers, but reveal another faster, positive S-cone signal. This signal is also likely to be the cause of constructive and destructive interference in the contrast-sensitivity data of ESCS observers.
| Type: | Article |
|---|---|
| Title: | Vision in observers with enhanced S-cone syndrome: an excess of S-cones connected mainly to conventional S-cone pathways but also a faster pathway |
| Open access status: | An open access version is available from UCL Discovery |
| DOI: | 10.1167/iovs.13-12897 |
| Publisher version: | http://dx.doi.org/10.1167/iovs.13-12897 |
| Language: | English |
| Additional information: | © The Association for Research in Vision and Ophthalmology, Inc. |
| Keywords: | Enhanced S-cone syndrome, Flicker sensitivity, Critical flicker fusion, Temporal processing, NR2E3, Temporal acuity, Short-wavelength-sensitive cones |
| UCL classification: | UCL UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Brain Sciences UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Brain Sciences > Institute of Ophthalmology |
| URI: | https://discovery.ucl.ac.uk/id/eprint/1419596 |
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