Fig. 2 Pupillary size in darkness of 1263 subjects chosen at random; average pupil size was used ([R + L]/2). Abscissa shows horizontal diameters in millimeters, ordinate shows subjects' age in years. Note the wide scatter but obvious age trend. See also Figure 3 (top curve). (Reprinted with permission from Loewenfeld IE: Pupillary changes related to age. In: Thompson HS, Daroff RB, Frisen L, et al (eds): Topics in Neuro-Ophthalmology. Baltimore: Williams Wilkins, 1979:129)