Refining Flash Visual Evoked Potential Analysis in Rats: A Novel Approach Using Bilateral Epidural Electrodes

Area of Science:

• Neuroscience
• Ophthalmology
• Preclinical Research

Background:

• Visual evoked potentials (VEPs) objectively measure visual pathway integrity.
• Flash VEPs (fVEPs) are sensitive to external variables, complicating inter-eye comparisons.
• Existing methods struggle with accurate relative visual function assessment between eyes.

Purpose of the Study:

• To develop a repeatable and accurate method for comparing visual function between diseased and healthy optic nerves.
• To improve the signal-to-noise ratio and reliability of fVEP measurements.
• To create a mathematical formula for estimating functional differences between optic nerves.

Main Methods:

• Utilized the rodent non-arteritic anterior ischemic optic neuropathy (rNAION) model.
• Employed implanted bilateral epidural electrodes for fVEP recording.
• Developed a mathematical formula to calculate relative visual function, validated with OCT, visual acuity, and RGC survival.

Main Results:

• The novel approach significantly improved signal-to-noise ratio and repeatability compared to subcutaneous methods.
• The derived formula accurately estimates functional differences, accounting for afferent input asymmetry.
• Calculated visual function strongly correlated with RGC survival and visual acuity.

Conclusions:

• A repeatable and accurate method was developed to assess relative visual function in optic nerve disease models.
• This novel method enhances fVEP measurement sensitivity and accuracy in preclinical trials.
• The technique reduces the number of animals required for statistically significant results.