Purpose:
To compare chromatic VEP response to isoluminant red–green stimulus in children with congenital red–green color deficiency with a control group of 30 children with normal color vision. 10 children (8–16 years) with congenital color vision deficiency (7 in deutan and 3 in protan axis) and 30 healthy children (7–19 years) were included in the study. Color vision was assessed with Ishihara plates, Farnsworth–Munsell hue 100 test and Farnsworth–Munsell D–15 test. VEP to isoluminant red–green stimulus were recorded. Isoluminant point was determined for each child subjectively by using heterochromatic flicker photometry, and objectively from recordings. The stimulus was a 7 deg large circle composed of horizontal sinusoidal gratings, with spatial frequency 2 cycles/deg and 90 % contrast. VEP were recorded from Oz (mid occipital) position. Children were tested binocularly. The properties (latency and amplitude) of the negative and positive wave were analyzed. Results were compared between the two groups.
Results:
The negative wave, which occurred prior to the positive wave, was recorded in 30 % (3/10) of children with color vision deficiency and in 80 % (24/30) of children from the control group. The positive wave was recorded in 90 % (9/10) of children with color vision deficiency and in all children from the control group. Mean values of the latency and amplitude from both groups are presented in the table.
Group data show that children with color vision deficiency had lower amplitude of the negative wave as compared to children with normal color vision. Furthermore, children with color vision deficiency did not show age–dependent linear decrease of the positive wave latency as was observed in the control group.
Conclusions:
VEP response to isoluminant chromatic stimulus showed different features in children with congenital color vision deficiency compared to children with normal color vision.
Keywords: electrophysiology: clinical • color vision