July 2019
Volume 19, Issue 8
Open Access
OSA Fall Vision Meeting Abstract  |   July 2019
Longitudinal chromatic aberration provides a temporal signal for the sign of defocus for emmetropization in chick at low contrast
Author Affiliations
  • Frances Rucker
    New England College of Optometry
  • Rhea Eskew
    Northeastern University
  • Christopher Taylor
    New England College of Optometry
Journal of Vision July 2019, Vol.19, 106. doi:https://doi.org/10.1167/19.8.106
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      Frances Rucker, Rhea Eskew, Christopher Taylor; Longitudinal chromatic aberration provides a temporal signal for the sign of defocus for emmetropization in chick at low contrast. Journal of Vision 2019;19(8):106. https://doi.org/10.1167/19.8.106.

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      © ARVO (1962-2015); The Authors (2016-present)

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Chicks respond to a spatial chromatic signal from LCA that predicts increased growth of the vitreous chamber when short-wavelength cone contrast (S-cone) is greater than long-wavelength cone contrast (L-cone). Contrarily, they also grow less in blue monochromatic light than in red. The goal of this experiment was to determine whether chicks also respond to temporal chromatic signals from LCA and whether blue light is essential.


457 chicks were exposed to flickering illumination for three days on an 8/16 hour light/dark cycle. Sinusoidal flicker (0.2 and 10 Hz) was presented at low (30%) and high contrast (80%), in two conditions: “White+B” (S cone modulation included) or “White-B” (S-cones unmodulated). In White-B conditions, the ratio of M to L modulations was varied. In White+B conditions, the ratio of S to (L&M) was varied. Eye measurements were made with a Lenstar LS 900 and a Hartinger refractometer.


Changes in both vitreous chamber depth and refraction depended upon the ratio of S to (L&M) modulations, at both 0.2 and 10 Hz, when contrast was 30%. In general, myopic changes were greatest for S-cone isolating and near-S-cone isolating flickers at the high temporal frequency; small hyperopic effects were found at the low temporal frequency. Vitreous chamber depth and refraction changed little when S cones were unmodulated.


With S-cone modulation, a temporal frequency dependent chromatic signal from LCA directs vitreous chamber growth and refraction but only at low contrast.


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