Effect of simulated octant visual field defects on the visual evoked potential (VEP)

Gender-based normative values for pattern-reversal and flash visually evoked potentials under binocular and monocular stimulation in healthy adults

PURPOSE

To determine gender-based normative values for pattern-reversal (PR) and flash (F) visually evoked potentials (VEP) under binocular and monocular stimulation in healthy adults.

METHODS

Healthy adults (age ≥18 years) were recruited among university employees and students. Inclusion criteria were absence of abnormalities in fundoscopy, tracking ability, stereopsis and pupillary reflexes; best-corrected visual acuity ≤.00 logMAR; and refractive error (spherical equivalent) from -6.00 to +6.00. Exclusion criteria were previous intraocular surgery, systemic and/or neurological disorders. Binocular and monocular tests were performed according to International Society for Clinical Electrophysiology of Vision standards for PRVEP (reversal rate = 1.9 Hz, checkerboard stimuli 15' and 60' at 100% contrast) and FVEP (3 cd s/m², rate = 1 Hz). VEP parameters of amplitude (µV) and peak times (ms) were measured. Inter-ocular differences, inter-peak intervals (N135-N75) and binocular summation were determined.

RESULTS

Fifty-four subjects (28 females; mean age = 40.4 ± 13.7 years; median = 40.0 years) were included. Mean P100 latencies for 15' and 60' stimuli were, respectively, 94.6 ± 4.7 ms and 96.1 ± 4.2 for women. Mean values of P100 latency for men were 97.4 ± 4.9 for 15' and 97.7 ± 4.2 for 60' stimuli. Larger mean P100 for 15' checks was observed in women (12.8 ± 5.7 µV) than men (8.6 ± 2.5 µV) in PRVEP. Similar results were found for FVEP N2-P2 amplitudes (mean = 14.6 ± 4.9 for women and 9.8 ± 4.0 for men).

CONCLUSIONS

Gender-based normative values for PRVEP and FVEP were determined, with women disclosing higher responses than men for smaller stimuli in the visual pathway. The use of gender-based normative values in the analysis of clinical VEP data for diagnostic and therapeutic purposes is recommendable. Additional analysis including inter-peak intervals and binocular summation ratio might improve the diagnostic power of VEP.