Abstract
Purpose: :
To establish normative values for Focal ERG in healthy adults, according to the standard protocol recommended by the International Society for Clinical Electrophysiology of Vision– ISCEV.
Methods: :
Normal healthy volunteers were assigned into two age groups: 33 aging from 14 to 38 years (mean age=22.96 ± 5.73) and 32 aging from 49 to 84 years (mean age=63.61 ± 8.52 ) and included according to the following criteria: BCVA ≥ 0.1 logMAR for distance; normal fundus, absence of previous ocular surgery, absence of visual complaints. Focal ERG was recorded by corneal electrode after white flicker light stimulation in the macula using 42Hz temporal frequency. ERG parameters as amplitude (nanovolts) and latency (miliseconds) were extracted and analyzed after discrete Fourier transform. Median and percentiles were calculated for both groups; a t–test was performed to analyze possible differences in amplitudes and latencies between age groups.
Results: :
Amplitude was significantly larger in the younger group (p= 0.001). Latency was comparable for two groups. There were no differences between males and females for both parameters. Amplitudes (nV) found in the younger and older groups were respectively: median – 614 and 486; percentile 2.5% – 378.8 and 201.8. Latencies (ms) found in the younger and older groups were respectively: median 26.4 and 26.1; percentile 97.5% – 27.88 and 30.32.
Conclusions: :
Normal limits for focal electroretinography according to ISCEV guidelines were established in a cohort of young and older adults. There was a decrease in amplitude with aging consistent with previous full–field ERG findings.
Keywords: electroretinography: clinical • retina • aging