Abstract
Commonly encountered environmental spectra can be narrow (e.g. short wavelength blues; long wavelength reds) or contain approximately equal levels of radiance across the spectrum (de-saturated colors, whites). Because of the longitudinal chromatic aberration in the human eye (>2D change in refraction across the visible spectrum), these spectral differences will affect retinal image quality. Changing color can alter the eye's refractive error, while increasing the spectral width will reduce image quality. We measured the radiance spectra of various colored images (flowers, leaves, concrete, sand, CRT and LCD monitors, etc). Using computational optics, the optimum refraction and polychromatic image quality for each spectra were calculated for a 5mm diameter pupil with or without typical levels of monochromatic aberrations. The range of refraction across the various spectra was 0.71D for an eye free of monochromatic aberrations but was significantly lower in the presence of monochromatic aberrations. Image quality was best for narrow spectra (e.g. blues and greens) and lowest for whites and purples. Our results show that environmental spectra can have a significant impact on the refractive state of the eye, possibly providing a continuously varying stimulus to accommodation as different colors are viewed.