Assessing the Effect of Opium Dependence on Visual Evoked Potential (VEP) in Men

BACKGROUND Opium-dependence having different effects on the nervous system is a common problem, especially in the Middle East and Iran. The aim of this study is evaluating the effects of opium-dependence on visual evoked potential (VEP) in men. METHODS Thirty subjects with both chronic cigarette smoking and opium-dependence (group 1) and 30 subjects with only chronic cigarette smoking (group 2) were included in this cross-sectional case-control study and after urinary tests of opium, the pattern reversal visual evoked potentials (PRVEP) were recorded in the standard condition and variables such as N75, P100, N135 and amplitude were obtained and then analyzed with SPSS16. P value < 0.05 was assumed significant statistically. FINDINGS The mean of N75 (70.426 ± 22.028), P100 (115.457 ± 29.176) and N135 (165.402 ± 66.712) was not significantly different between the two groups. The mean of the amplitude of VEP in group 1 (6.856 ± 3.248) was significantly higher than group 2 (4.933 ± 2.50) (P < 0.05). CONCLUSION Our study showed that chronic cigarette smoking and opium dependence have no significant effect on the late components of the VEP (N75, P100 and N135), but chronic cigarette smoking and opium-dependence together significantly increase the amplitude of VEP compared with chronic cigarette smoking alone, probably due to the chronic stimulatory effects of concomitant use of these two substances on the eyes and the visual nervous system.