Visually evoked potentials.

Area of Science:

• Neuroscience
• Ophthalmology
• Clinical Electrophysiology

Background:

• Visually evoked potentials (VEPs) are electrical signals recorded from the scalp over the visual cortex.
• VEPs are derived from the electroencephalogram using signal averaging, typically with electrodes on the occipital scalp.

Purpose of the Study:

• To explain the principles and applications of visually evoked potentials (VEPs).
• To highlight VEPs' utility in assessing the functional integrity of the visual pathways and occipital cortex.
• To illustrate how VEP abnormalities can indicate neurological and visual pathway disorders.

Main Methods:

• VEPs are recorded by placing electrodes on the occipital scalp.
• Stimulation methods include patterned stimuli on video monitors for older children and adults.
• Flash stimuli (strobe or LEDs) are used for infants and sedated patients.
• Multifocal VEPs extend mapping beyond the central visual field.

Main Results:

• VEPs quantify the functional integrity of the optic nerves, visual pathways, and occipital cortex.
• Abnormalities affecting neuronal transmission (e.g., multiple sclerosis) or optic nerve compression (e.g., tumors) alter VEPs.
• VEP wave peak latency can be slowed by conditions like demyelination or gliomas.

Conclusions:

• VEPs are a valuable non-invasive tool for diagnosing and monitoring visual pathway disorders.
• VEP analysis provides objective measures of visual system function.
• Different VEP recording techniques cater to various patient populations and diagnostic needs.