Assessment of the Visual Evoked Response Parameters in Different Hemi Fields in Normal Subjects

Visual Evoked Potential is an objective method to assess the visual function. The purpose of this study was to evaluate the visual evoked responses in different hemi fields of vision in normal individuals.
The study included 80 eyes of normal subjects aged 18-38 years. All participants were underwent detailed examination including refraction and visual acuity. Pattern reversal VEP responses were recorded in different hemi­ fields. Repeated Measures Analysis of Variance (SPSS statistical software, Version 20) was used to compare responses recorded in different hemi fields, amplitude and latency of VEP.
The averages of maximum and minimum value of P100 amplitude were found in the temporal and inferior retinas, respectively. Moreover, lowest latency was observed in the superior retina and greatest latency was in the nasal retina. The results showed a significant difference in P100 amplitude and latency between different hemi fields.
This study revealed the details of local VEP distribution in the visual field and there was a significant difference in the amplitude and latency of the VEP wave in different hemi fields of vision. In our study, the most visual sensitivity (lowest latency and maximum amplitude) is in the superior and temporal retinas, which has the lowest latency and the highest amplitude, respectively. Superior and temporal areas of the retina seem to have a better response in the PVEP test.