Abstract
We have developed an apparatus and psychophysical paradigm for the reliable and practical measurement of light absorption by the human crystalline lens. Using this procedure we can partition a loss of sensitivity with aging into that attributable to changes in the lens and that due to other factors. The procedure eliminates effects of inaccurate refractive correction and misalignment, and reduces the effects of pupil size. Results on 84 eyes showed a gradual decrease in sensitivity with age, especially for short wavelengths. We noted considerable individual variability, which points up the value of using a procedure that assesses sensitivity loss due to lens absorption for each tested individual.