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The optic nerve head component of the human ERG
1Smith-Kettlewell Eye Research Institute, San Francisco, CA 94115, USA. ees@skivs.ski.org
Vision Research
|May 26, 1999
Summary
A novel optic nerve head signal component was identified using multifocal electroretinography (mfERG). This component
Area of Science:
- Ophthalmology
- Neuroscience
- Visual Electrophysiology
Background:
- The multifocal electroretinogram (mfERG) assesses retinal function.
- Local mfERG responses show continuous waveform changes across the retina.
- An unexplained additive component in mfERG signals was observed.
Purpose of the Study:
- To investigate the origin of an additive signal component in mfERG.
- To test the hypothesis of an optic nerve head (ONH) contributing source.
Main Methods:
- Two independent electrophysiological methods were employed.
- Method 1: Modeled local mfERG waveforms using two fixed components with variable latency.
- Method 2: Used differential reference electrode placements to isolate ONH signals.
Main Results:
- A two-component model provided an excellent fit for mfERG waveforms.
- Both methods consistently identified a signal component originating near the optic nerve head.
- Derived signal latencies correlated with optic nerve fiber layer propagation delays.
Conclusions:
- Strong evidence supports a signal source near the optic nerve head.
- This finding advances understanding of visual pathway electrophysiology.
- mfERG analysis can reveal contributions beyond the retina.