Chromatic visual evoked potentials in paediatric population.

Background: The purpose of this study was to investigate chromatic visual evoked potential (cVEP) response characteristics during the first year of life and to collect as large database of healthy baby responses as possible. This study also complements our previous studies on cVEP in schoolchildren and preschool children.
Methods: Forty-four healthy babies aged 3-12 months were binocularly tested. cVEP were recorded to isoluminant red-green (R-G) and blue-yellow (B-Y) stimuli. The stimulus represented a circle composed of horizontal sinusoidal gratings with 90 % chromatic contrast and spatial frequency of 2 cycles/deg. Two stimulus sizes (7° and 21°) and onset-offset mode of stimulation (On-300 ms, Off-700 ms) were used. cVEP were recorded from Oz (mid-occipital) position with the reference at Fz. Waveform characteristics and its changes throughout the first year of life were studied.
Results: Chromatic visual evoked potential responses were reliably recorded in all but two youngest babies. Characteristic cVEP response consisted of negative-positive-negative complex, positive (P) wave being far more prominent than both negative waves (N1 and N2). cVEP response to larger stimulus size (21°) showed shorter latency and higher amplitude to both (R-G) and (B-Y) stimuli compared to smaller stimulus size (7°). The same was true when comparing R-G versus B-Y stimulus: R-G responses showed higher amplitude and shorter latency than B-Y response, for both stimulus sizes. P wave latency shortened with increasing age throughout the first year of life, both for R-G (R (2) = 0.59) and B-Y (R (2) = 0.41) 21° stimulation. P wave amplitude did not show significant changes throughout the first year of life.
Conclusions: Chromatic visual evoked potential can be reliably recorded after the age of 3 months and show significant maturational changes throughout the first year of life.