A signal for defocus for emmetropization arising from longitudinal chromatic aberration in chick.

A signal for defocus for emmetropization arising from longitudinal chromatic aberration in chick. Exp Eye Res. 2020 Jul 24;:108126 Authors: Rucker FJ, Eskew RT, Taylor C Abstract Chicks respond to two signals from longitudinal chromatic aberration (LCA): a wavelength defocus signal and a chromatic signal. Wavelength defocus predicts reduced axial eye growth in monochromatic short-wavelength light, compared to monochromatic long-wavelength light. Wavelength defocus may also influence growth in broadband light. In contrast, a chromatic signal predicts increased growth when short-wavelength contrast > long-wavelength contrast, but only when light is broadband. We aimed to investigate the influence of blue light, temporal frequency and contrast on these signals under broadband conditions. Starting at 12 to 13 days-old, 587 chicks were exposed to the experimental illumination conditions for three days for 8h/day and spent the remainder of their day in the dark. The stimuli were flickering lights, with a temporal frequency of 0.2 or 10 Hz, low (30%) or high contrast (80%), and a variety of ratios of cone contrast simulating the effects of defocus with LCA. There were two color conditions, with blue contrast (bPlus) and without (bMinus). Stimuli in the "bPlus" condition varied the amounts of long-(L), middle- (M_) and double (D-) cone contrast, relative to short- (S-) and (UV-) cone contrast, to simulate defocus. Stimuli in the "bMinu...
Source: Experimental Eye Research - Category: Opthalmology Authors: Tags: Exp Eye Res Source Type: research