The Effect of Spatial Frequency on Visual Evoked Potentials Components in Visual Acuity Assessment

Objective measurement of visual acuity using VEP is high valued in patients with low levels of cooperation. Therefore, this study aimed to investigate the effect of spatial frequency on VEP components in visual acuity using Sweep VEP.

In this cross-sectional study 63 medical students with an age of 22.81 ± 3.93 were selected. After a completed eye examination, refractive error was determined, and best-corrected visual acuity as subjective was recorded by the Freiburg Acuity contrast test. Sweep VEP using the Roland electrophysiology system was recorded for various spatial frequencies from 2 to 37.5 cycles per degree. VEP components were the latencies of N1, P1, N135, and the amplitude of VEP.

Repeated measures of the ANOVA test showed that the effect of spatial frequency on latencies and amplitude of VEP was significant (P<0.001). Paired T-test showed that there was a significant difference between subjective visual acuity and extrapolation of visual acuity with VEP (P<0.001).

According to the significant relationship between VEP amplitude and spatial frequencies of the visual stimuli obtained in this study, the Sweep VEP technique can be used as a valid and objective tool in the determination of visual acuity, especially in patients with low levels of cooperation.