Spectral reflectance of the human eye.

Spectral reflectance of the eye was assessed in four young Caucasian subjects with the Utrecht densitometer. Three retinal locations were studied, the fovea, the optic disk and a spot 12 deg temporal on the horizontal meridian. Reflectance was measured with the visual pigments bleached away. The measuring field subtended 2.5 deg. The reflectance factor, relative to an artificial eye with a focal distance of 21.3 mm, was found to be lowest in the blue (0.1% for 419 nm) and highest in the red (10% for 711 nm). A model with six parameters, four densities of (non-photolabile) ocular pigments and two reflectance factors, was proposed to explain the experimental findings. A good fit to the data was obtained and the calculated densities of the ocular pigments came close to data found in the literature.