ArticleAlexandridis E, Manner M.
Albrecht Von Graefes Arch Klin Exp Ophthalmol. 1977 May 23;202(3):175-80.
Pupillary function was tested in 3 different age groups (20-30, 40-50, 60-70 years) of 8 patients each. The pupillary response was picked up by means of a portable IR-reflex-pupillometer, which registered the consensual pupillary light reflex in one eye, while the other eye was stimulated by flashes of different frequencies. Measurements were made of how many Hertz (Hz) the pupil dilated in the dark phases (intervals) between the flashes (flicker-fusion frequency). In the younger age group an average value of 3.15 Hz was obtained, the middle group fused at 2.89 Hz, the older group at 2.61 Hz. These differences are explained mainly by muscular and vascular degeneration of the iris.