Dark-adapted red flash ERGs in healthy adults

Area of Science:

• Ophthalmology
• Neuroscience
• Physiology

Background:

• The dark-adapted (DA) electroretinogram (ERG) x-wave reflects DA cone function.
• Optimizing the visualization and quantification of the x-wave is crucial for understanding retinal function.

Purpose of the Study:

• To investigate how flash strength and dark adaptation duration affect the DA red ERG x-wave in healthy adults.
• To identify optimal parameters for visualizing and quantifying the x-wave.

Main Methods:

• Investigated the effect of red flash strength (0.2-2.0 cd·s·m⁻²) on DA red ERGs in 4 subjects after 20 min dark adaptation.
• Examined the effect of dark adaptation duration (1-20 min) on DA red ERGs (1.5 cd·s·m⁻²) in 16 subjects using skin electrodes.

Main Results:

• X-wave visibility was better with weaker red flashes (<0.6 cd·s·m⁻²) after 20 min dark adaptation; stronger flashes obscured it.
• For 1.5 cd·s·m⁻² flashes, the x-wave was most prominent after 1-5 min of dark adaptation, becoming less distinct with longer adaptation.

Conclusions:

• X-wave visibility in healthy subjects is enhanced by using red flashes <0.6 cd·s·m⁻² after 20 min dark adaptation.
• For 1.5 cd·s·m⁻² flashes, recording around 5 min of dark adaptation maximizes x-wave visibility.
• No evidence suggests interim red flash ERGs alter the dark-adapted state of the normal retina.