Effects of aging on visual evoked responses.

The effects of aging of visual evoked responses (VER) and critical frequency of photic driving (CFPD) was studied in 74 volunteers aged 18 to 79. The amplitude of VER to pattern reversal stimulation did not vary with sex or age. The latencies of the first major negative and of the first major positive defection of the VER were significantly delayed (P less than .001) with advancing age. This increase of latency probably reflects a slowing of conduction velocity in the optic nerve or optic pathways or both. CFPD, defined as the highest frequency of photic driving response expressed in flashes per second, showed an inverse correlation, decreasing with age in older subjects. Critical frequency of photic driving is the electrophysiological counterpart of critical flicker fusion, which is known to decrease with advancing age. These data support the concept that aging influences the functions of specialized sensory systems.