2020–2021 BCSC Basic and Clinical Science Course™
3 Clinical Optics
Chapter 1: Geometric Optics
Aberrations
Chromatic Aberration
In addition to these “monochromatic” aberrations, images produced by white light may also be degraded by chromatic aberration, the spreading apart of colors of white light by a lens system. This effect is caused by dispersion, by which the index of refraction of a material medium may vary with the wavelength of the light passing through it. Just as a prism bends blue light more strongly than it bends red light, in practice, a convex lens will create a focal point for blue light anterior to the one for red light, so the eye is typically about 0.5 D more myopic for images formed in blue light than in red light. This disparity is the basis for the Lancaster red-green (“duochrome”) test for accommodative control (see the Quick-Start Guide).
Excerpted from BCSC 2020-2021 series : Section 3 - Clinical Optics. For more information and to purchase the entire series, please visit https://www.aao.org/bcsc.