Objective detection of visual field defects with multifrequency VEPs.

Area of Science:

• Ophthalmology
• Neuroscience
• Visual Electrophysiology

Background:

• Visual field loss is a key indicator of glaucoma, often detected through perimetry.
• Objective electrophysiological methods are needed for sensitive and reliable visual field assessment.

Purpose of the Study:

• To correlate multifrequency pattern reversal visual evoked potentials (VEPs) in quadrants (QmfrVEPs) with perimetric field losses.
• To evaluate QmfrVEPs for objective detection of visual field losses in glaucoma patients.

Main Methods:

• QmfrVEP measurements were performed monocularly in normal subjects and glaucoma patients using four LED-based checkerboard stimulators.
• Discrete Fourier analysis identified responses to stimuli with slightly varied reversal frequencies (11.92-12.16 reversals/sec).
• The highest signal-to-noise ratio (SNR) recording was used for analysis.

Main Results:

• QmfrVEP responses from different quadrants were reliably measured and separated.
• A significant correlation was found between SNR and perimetric visual field losses (Spearman rank correlation: P < 0.001).
• Glaucoma patients showed reduced SNR in quadrants with perimetric defects, confirming the procedure's sensitivity.

Conclusions:

• QmfrVEP responses are reliably measurable and can be used for objective assessment.
• High SNR values in QmfrVEPs can exclude visual field defects.
• Focal visual field defects in glaucoma patients can be identified using QmfrVEPs.