The study of chromatic and achromatic VEP in the first year of life

Purpose To study chromatic and achromatic VEP responses in the first year of life. Methods In 30 babies aged 2 to 12 months VEP to chromatic and achromatic stimuli were binocularly recorded. Chromatic VEP were recorded to isoluminant red-green and blue-yellow stimulus. The stimulus was a circle composed of horizontal sinusoidal gratings with 90 % chromatic contrast. Two stimulus sizes (7 deg and 21 deg) were used. The stimulus was presented in an onset-offset mode (on – 300ms, off – 700 ms). Achromatic VEP were recorded to black and white checkerboard (50′ square size), which was presented in pattern reversal (reversal VEP) and onset-offset (onset VEP) mode. VEP were recorded from Oz (mid occipital) position and the reference was at Fz. Results Chromatic VEP responses were present in all babies, except youngest two (2 months old). The positive wave (P) amplitude to red-green and blue-yellow stimulus increased with age when using both stimulus sizes. Achromatic VEP responses were present in all babies. P100 wave (pattern reversal stimulation) showed longer latency in youngest babies (p=0.045), whereas its amplitude did not change throughout the first year of life. C1 wave (onset-offset stimulation) showed longer latency in youngest babies (p=0.0039), whereas its amplitude decreased with increasing age (p=0.0087). Conclusion Chromatic VEP responses can be recorded in babies after the age of 3 months and show marked maturational changes throughout the first year of life.