Pattern ERG: effects of reference electrode site, stimulus mode and check size.

Area of Science:

• Ophthalmology
• Neuroscience
• Visual Electrophysiology

Background:

• Pattern electroretinography (PERG) assesses retinal function.
• Visual evoked potentials (VEPs) can contaminate PERG signals.
• Optimizing reference electrode placement is crucial for accurate PERG recordings.

Purpose of the Study:

• To evaluate monocular and binocular pattern electroretinography (PERG) using different reference electrode placements.
• To determine the optimal reference electrode for minimizing visual evoked potential (VEP) contamination in PERG.
• To assess the impact of stimulation conditions on PERG parameters.

Main Methods:

• Monocular and binocular PERG were recorded in normal subjects and a patient with optic neuritis.
• Ipsilateral ear, temple, and midfrontal references were compared.
• VEP (P100/N100) contribution to PERG (N95) was analyzed.
• Effect of increasing check size on PERG latencies and amplitudes was investigated.

Main Results:

• No significant PERG from the occluded eye confirmed no cross-contamination in binocular testing.
• Ipsilateral temple reference minimized VEP (P100/N100) contamination of PERG (N95).
• Binocular stimulation resulted in smaller inter-eye amplitude ratio differences compared to monocular stimulation.
• Larger check sizes reduced P50 and N95 latencies and increased P50 amplitude.

Conclusions:

• The ipsilateral temple reference is optimal for reducing VEP contamination in PERG.
• Binocular PERG stimulation provides more reliable inter-eye amplitude comparisons.
• PERG parameters are influenced by check size, offering diagnostic potential.