Visual evoked potentials in children with high blood lead level

Introduction
The aim of this study is to find the relationship between lead level in blood (Pb-B) and visual evoked potentials (VEP) in children, environmentally exposed to lead.

Material and methods
32 children (64 eyes) with no clinical signs of lead poisoning were examined. Corrected visual acuity was 5/5 in all eyes. Age of the children was 2 – 15.5 years (mean 8), Pb-B ranged from 150 to 486 (mean 262) μg/l. For pattern VEP LKC equipment, UTAS E-2000 program and stimulations of 13’, 26’, 52’, 105’ were used. P100 amplitude and latency were calculated.

Results
P100 latency was significantly delayed in children at the age of seven, with Pb-B above 150 μg/l. The latencies were more delayed in children with higher than in lower Pb-B, but the relation was not linear. P100 amplitudes did not differ significantly from the control group. In some children VEP had abnormal morphology, double P100 peak or P100 without sharp, but extended peak.

Conclusions
Delayed P100 PVEP latency occurred in children with blood lead level higher than150 μg/l, after at least 7 years of environmental exposure. Changes in VEP are similar to those which are caused by demyelinization and are found in multiple sclerosis.