The effect of filter bandwidth on the multifocal electroretinogram

Area of Science:

• Ophthalmology
• Neuroscience
• Biomedical Engineering

Background:

• The multifocal electroretinogram (mfERG) is a critical tool for assessing retinal function.
• Understanding signal processing, including filtering, is essential for accurate mfERG interpretation.
• Previous studies have not fully elucidated the impact of filter bandwidth on mfERG waveform morphology.

Purpose of the Study:

• To investigate the influence of filter bandwidth on multifocal electroretinogram (mfERG) waveforms.
• To determine the specific effects of high-pass filtering on normal and negative mfERG waveforms.
• To provide recommendations for optimal filter settings in mfERG recordings.

Main Methods:

• Theoretical calculations were performed to model filter effects.
• Electronic simulations were used to replicate mfERG signal processing.
• Real-world mfERG recordings were conducted to validate theoretical and simulation findings.

Main Results:

• High-pass filtering was demonstrated to cause waveform distortion in simulated square waves and actual mfERG recordings.
• Negative mfERG waveforms exhibited significant differentiation effects with increased high-pass filter settings.
• This differentiation can artificially create a positive component resembling a b-wave, leading to misinterpretation.

Conclusions:

• Increasing the high-pass filter setting differentiates negative mfERG waveforms, potentially mimicking a b-wave.
• To preserve the integrity of mfERG waveforms and avoid misinterpretation, a high-pass filter setting below 1 Hz is recommended.
• Adhering to recommended filter settings ensures more accurate assessment of retinal function using mfERG.