Light filters to improve vision.

Visual impairment not only derives from deficient processes within the ocular tissues, but also from the quality and quantity of environmental lighting. High levels of short wavelength light are not used efficiently in eyes that have cloudy media anterior to the retina or whose cones are deficient. Chromatic aberration, light scattering, and fluorescence are enhanced by short wavelength lighting. We show here that in human vision and in photography, elimination of environmental light with wavelengths shorter than 450 nm improves both contrast and visual clarity, especially through cloudy media. Cutoff filters with appropriate characteristics could be developed to improve vision in elderly and visually impaired people whose ocular media mishandle short wavelength light.