Recent data in the literature on psychophysically determined in vivo intraocular straylight, and on in vitro fluorescence of the eye lens are analyzed. From the psychophysical straylight data, light scattering changes in the lens due to normal aging and age-related cataract formation are derived in physical terms. The intensities of these light-scattering changes prove to follow approximately cu p (u=scatter angle) with p'−2 and c dependent on age and cataract. Both p and c are in accordance with recent in vitro studies on light scattering using donor lenses. Fluorescence of the lens causes light with wavelengths of 420 nm and lower to be in total
visually much more effective: by a factor of 2.7 to 6.8 at 400 nm, and a factor of 71 to 151 at 380 nm. Because fluorescence adds a homogeneous veil to the point spread function, for some visual effects (e.g., glare) the increase can be (much) larger.