Multifocal magnetoencephalogram applied to objective visual field analysis

Area of Science:

• Neuroscience
• Ophthalmology
• Biophysics

Background:

• Objective visual field analysis is crucial for diagnosing and monitoring visual pathway disorders.
• Current methods may have limitations in sensitivity or objectivity.
• Magnetoencephalography (MEG) offers high temporal and spatial resolution for brain activity measurement.

Purpose of the Study:

• To establish an objective method for visual field analysis using visual evoked magnetic fields.
• To investigate the utility of multifocal visual evoked magnetic fields (mfVEFs) for mapping visual cortex activity.

Main Methods:

• The visual evoked response imaging system (VERIS) was used to stimulate 48 focal areas of the visual field.
• Multifocal visual evoked magnetic fields (mfVEFs) were recorded from 11 healthy subjects.
• Equivalent current dipoles (ECDs) were estimated and localized using magnetoencephalography (MEG).

Main Results:

• mfVEFs exhibited two- or three-peak waves, with larger amplitudes for stimuli within 6 degrees of the central visual field.
• All estimated ECDs originated in the occipital striate cortex.
• The topographical mapping of ECDs corresponded to the stimulated visual field locations.

Conclusions:

• The locations of mfVEF peak ECDs correlated with the stimulated visual field, aligning with the cruciform model.
• MEG, in conjunction with the multifocal technique, serves as a viable tool for objective visual field analysis.
• This approach enhances the objective assessment of visual field function.