How much light reaches the retina?

Abstract

There are three major prereceptoral factors governing the amount of light reaching the retina: pupil area, lens optical density and the optical density of the macular pigment. Standardized tabulations are available for each of these factors. These standard tabulations represent well the characteristics of an average observer and thus have application in modelling the behavior of a representative observer. In recent years significant advances have been made in the understanding of receptoral and postreceptoral retinal mechanisms, and it is now feasible to characterize aspects of these processes in individual observers from a relatively limited amount of psychophysical data. This communication addresses the question: are average tabulations for pupil, lens and macular pigment applicable to individual observers or is individual variability so great that independent assessment of these factors need be obtained?