Recovery of the Rod Photoresponse in Infants

PURPOSE. To study deactivation of the rod photoresponse in infants using a paired-flash procedure. Rhodopsin content in-creases and scales the parameters of the activation of rod phototransduction as rods develop. However, little is known about the kinetics of deactivation in the rods of young infants. METHODS. ERG responses to pairs of flashes were used to study the recovery of the rod response in 4- and 10-week-old infants and mature control subjects. The amplitudes of rod isolated a-wave responses to a probe flash (3.3 log scot td s) pre-sented 2 to 120 seconds after an equal-intensity test flash were measured. The interstimulus interval (ISI) at which the ampli-tude was half that of the response to the probe flash alone (t50) was determined by linear interpolation. RESULTS. Recovery time (t50) was significantly longer in infants than in adults (F 18.9, df 2, 32; P 0.01). The shape of th