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Jayasree Seshadri, Vasudevan Lakshminarayanan, Erwin Wong, Jerry Cristensen; Effect of wavelength on the nonius horopter. Journal of Vision 2007;7(9):828. doi: 10.1167/7.9.828.
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© ARVO (1962-2015); The Authors (2016-present)
The Horopter is defined as locus of points in space with zero binocular disparity and having identical visual direction. Previous studies have shown that the perceived visual direction of the object in space varies as a function of wavelength. We have investigated if this change in directionality is due to chromostereopsis and the Stiles Crawford effect [SCE]. The nonius horopter was measured in three observers as function of four different wavelengths. For each observer and wavelength, the horopter was measured foveally for both photopic and mesopic conditions. The horopters were measured for all conditions while viewing through 2 mm and 6 mm pinholes. Chromostereopsis was also recorded. The results for the different luminance conditions show that SCE reduces the effects of aberration and modifies the curves under photopic conditions compared to mesopic condition where SCE effect is minimal. There was also a reversal in the direction of the chromostereopsis from positive to negative with the different pinholes. This corresponded to the reversals in the horopter curves for the blue and red wavelengths under the same conditions. Therefore we conclude that the changes in the horopter curves are due to both optical and neural factors.
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