The multifocal visual evoked potential: an objective measure of visual fields?

Area of Science:

• Ophthalmology
• Neuroscience
• Visual Science

Background:

• Automated static perimetry is a common method for assessing visual field sensitivity.
• However, results can be affected by patient attention and cognitive load.
• Objective electrophysiological measures may offer a more reliable alternative.

Purpose of the Study:

• To investigate the impact of divided attention on Humphrey visual field sensitivity and multifocal visual evoked potential (mfVEP) amplitude.
• To determine if mfVEP is a reliable objective measure of visual function under cognitive load.

Main Methods:

• Four normally sighted subjects underwent monocular Humphrey visual field testing and mfVEP recordings.
• Testing was performed under standard conditions and during a concurrent mental arithmetic task (Paced Auditory Serial Addition Task - PASAT).
• mfVEPs were recorded using a 60-sector stimulus with contrast reversal based on m-sequences.

Main Results:

• Humphrey visual field sensitivity was significantly reduced at multiple locations when subjects performed the PASAT compared to the no-task condition.
• No significant decreases in mfVEP amplitude were observed in any sector for any subject during the PASAT.
• This indicates that divided attention did not impact mfVEP amplitude.

Conclusions:

• Multifocal visual evoked potential (mfVEP) is not affected by divided attention or mental arithmetic.
• mfVEP serves as a robust objective measure of visual field function.
• mfVEP may be particularly valuable for patients with unreliable automated static perimetry results due to attentional deficits.