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Clarissa Kum, Dejana Grk, Philip B. Kruger, Mitchell Dul, Lawrence R. Stark; Is Reversed Chromostereopsis Associated with Impaired Accommodation to Wavefront and Chromatic Aberration?. Invest. Ophthalmol. Vis. Sci. 2012;53(14):1370. doi: https://doi.org/.
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Ocular accommodation to wavefront and chromatic aberration varies widely among observers. Reasons for the large inter-subject variation are unknown. Positive chromostereopsis (red targets appear closer than blue targets when viewed binocularly on a black background) is reversed in a minority of the population, so that blue targets appear closer than red. Since chromatic aberration specifies distance and relative depth both monocularly and binocularly, our aim was to determine whether negative (reversed) chromostereopsis influences accommodative gain to wavefront and chromatic aberration.
Chromostereopsis was measured in 30 observers (21-27 yrs) using a checkerboard target of 64 (8x8) red and blue squares on a black background viewed at 1 meter. Luminance of the blue and red squares was matched (22 cd/m2) and blur of blue and red squares was matched using trial lenses. The subject was asked whether the blue and red squares appeared equidistant or whether blue or red squares appeared closer. Relative depth was measured monocularly and binocularly. Accommodation was recorded at 100 Hz while viewing a high contrast Maltese cross in a Badal optical system through a 3 mm artificial pupil, while wavefront vergence (Zernike defocus) changed sinusoidally (1-3 D) at 0.2Hz. Six trials were run in white light (3000K; 20 cd/m2) and six in monochromatic light (550 nm: 12nm bandwidth; 20 cd/m2). Each trial lasted 40.96 seconds. Dynamic gains and temporal phase-lags of accommodation were extracted by Fourier transform of the data.
Seventeen subjects (57%) had positive chromostereopsis and accommodation gains varied between 0.1 and 0.8. Four subjects (13%) had negative chromostereopsis and their respective accommodation gains were 0.1, 0.4, 0.4 and 0.9. Nine subjects (30%) reported no chromostereopsis and gains varied between 0.1 and 0.8. Gains for the three groups were not significantly different (Kruskal-Wallis one-way ANOVA; KW = 0.37; p > 0.8).
Reversed chromostereopsis does not seem to influence accommodation to wavefront and chromatic aberration.
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