Abstract
Purpose: :
To assess age-related changes in retina function in humans, using the full field electroretinogram (ERG).
Methods: :
ERG recordings were performed on healthy individuals aged 20 to <40y (n = 25 mean age 24), 40 to <60y (n = 21 mean age 52), and 60 to <80y (n = 17 mean age 68). Three tests were applied: 1) light adapted intensity responses; 2) dark-adapted intensity responses; and 3) dynamic of recovery from a single bright flash.
Results: :
Changes in ERG properties were found in the oldest group when compared to the two younger groups. 1) The photopic hill effect was less pronounced (this effect means that an apex in b-wave amplitude at flash intensities of 0.5 to 1 log cds/m2 is followed by a reduction at brighter flashes). 2) Both photopic a-wave and b-wave implicit times were prolonged; 3) Dark-adapted a-wave but not b-wave amplitudes were reduced, yielding higher b/a ratios; 4) Implicit times of the dark-adapted a- and b-waves were prolonged: there was a direct correlation between minimal a-wave implicit times (always obtained to the brightest flash) and age. 5) The dynamic of recovery of both a-wave and b-wave amplitudes from a bright flash was faster.
Conclusions: :
The healthy retina undergoes age-related functional changes as assessed with the full field ERG. A less pronounced photopic hill may reflect changes in the off-bipolar system. The slowing of implicit times may suggest the occurrence of intrinsic biochemical changes in retinal cells such as photoreceptors. Finally, the selective reduction of maximal dark-adapted a-wave amplitudes may be linked to post-synaptic compensations.
Keywords: electroretinography: clinical • aging