Sex-independent visual evoked potential complexity.

OBJECTIVE

Visual evoked potentials (VEPs) provide a non-invasive measure of visual pathway function, traditional analyses focusing on peak latency and amplitude may overlook the dynamic complexity of cortical processing. This study examined whether VEP signal complexity differs between sexes using a non-linear fractal approach based on the correlation dimension (D₂).

METHODS

Eighty-eight healthy adults (39 females, 49 males; mean age 37 years) underwent pattern-reversal VEP testing for each eye using two checkerboard field sizes (0.808° and 0.258°), preferentially engaging magnocellular and parvocellular pathways. The complexity of averaged VEPs was quantified using the Grassberger-Procaccia algorithm with optimised embedding parameters. Sex and eye effects were analysed separately for each stimulus condition.

RESULTS

No significant main effects or interactions of sex or eye were observed for either checkerboard size. Estimated D₂ values ranged from 3.3 to 3.6 across conditions. Although females showed numerically higher P100 amplitudes, particularly for small-checkerboard stimulation, and a subtle tendency toward longer response latencies for left-eye stimulation, these differences were not reflected in D₂.

CONCLUSIONS

The fractal dimensionality of early visual cortical responses is stable across sex, eye, and stimulus parameters.

SIGNIFICANCE: Correlation dimension (D₂) analysis can be applied to averaged visual evoked potential (VEP) data from healthy adults without stratifying participants by sex.