[Examination of visual evoked potentials in persons exposed to prolonged contact with ethyl benzene vapors]

The aim of this study is an estimation of the visual evoked potentials (VEP) of persons exposed to prolonged contact with leaded petrol.

A group of 90 males aged between 22 and 53, exposed to prolonged contact with leaded petrol for the period of between a few months to 30 years, was examined. Those examined were divided into three groups depending on the length of exposure: group 1 up to 10 years, group II-11-20 years, group III-20 years and more. The results were compared with those obtained from a group of 40 healthy age-matched males, not exposed to leaded petrol. In neurological and ophthalmological examinations no pathological symptoms were detected in both groups. The VEP examination was executed using pattern reversal (pr) and pattern flash (pf) stimulation.

The frequent pathological record of VEP was an elongation in the latency of P-100 and reduction of response amplitude. Using pr stimulation, the reduction of the mean value of the amplitude for group III was found statistically significant (p < 0.01). In pf examination in group III mean latency of the P-100 was significantly statistically (p < 0.01) longer than in the control group. Significant reduction of the response amplitude in groups II (p < 0.01) and III (p < 0.001) was found in this type of stimulation.

The results of studies indicate subclinical damage of the visual pathway particularly of persons exposed to leaded petrol vapour during work for longer than 20 years.