'Normal' and 'abnormal' crossed asymmetry in monocular visual evoked potentials

Area of Science:

• Neuroscience
• Ophthalmology
• Visual Electrophysiology

Background:

• Crossed asymmetry in visual evoked potentials (VEP) is a known phenomenon.
• Understanding normal versus abnormal patterns is crucial for diagnosing visual pathway disorders.

Purpose of the Study:

• To investigate the occurrence and characteristics of crossed asymmetry in normal subjects using FVEP and PSVEP.
• To differentiate between normal and abnormal crossed asymmetries in visual evoked potentials.

Main Methods:

• Tested 29 normal subjects.
• Utilized full-field visual evoked potential (FVEP) and pattern-shift visual evoked potential (PSVEP) studies.
• Analyzed the laterality of Wave III and P100 components in relation to the stimulated eye.

Main Results:

• 'Normal' unidirectional crossed asymmetry was observed in 20% of subjects on FVEP, but not on PSVEP.
• Larger Wave III contralateral to the stimulated eye defined 'normal' crossed asymmetry.
• Ipsilateral larger Wave III or P100 crossed asymmetry on PSVEP indicated 'abnormal' patterns.

Conclusions:

• A subset of normal individuals exhibits unidirectional crossed asymmetry on FVEP.
• Deviations in VEP asymmetry, particularly concerning Wave III and P100 laterality, can signify abnormal crossed asymmetries.
• Normal crossed asymmetry may be present in certain pathological conditions involving optic misrouting.