The relationship between feline pupil size and luminance

The relationships between luminance and height, width or area of the feline pupil were investigated in awake, normal adult cats whose pupils were photographed over a range of light levels with the aid of electronic flash. The results are compared with previous measurements of pupil width and height in awake animals (Kappauf 1943); and with estimates of pupil width, height and area in lightly-anaesthetised cats (Wilcox and Barlow 1975). The implications of these results for retinal illumination and colour discrimination are discussed.