The multifocal electroretinogram (mfERG) in the pig.

Area of Science:

• Ophthalmology
• Neuroscience
• Animal Models

Background:

• Multifocal electroretinography (mfERG) is crucial for assessing retinal function.
• Standardizing mfERG in animal models like pigs is essential for translational research.
• Characterizing the porcine retina's electrophysiological properties aids in understanding visual processing.

Purpose of the Study:

• To develop and validate a method for simultaneous mfERG recording and fundus monitoring in anesthetized pigs.
• To characterize the electrophysiological peaks (N1, P1, N2) of the porcine mfERG.
• To compare mfERG responses in the visual streak with non-responsive areas like the optic nerve head and to demonstrate the method's feasibility by inducing a laser burn.

Main Methods:

• mfERG recordings were performed on fifteen pigs at baseline and at 1 and 6 weeks.
• One pig underwent mfERG before and after retinal laser treatment in the visual streak.
• Simultaneous fundus monitoring was employed during mfERG recordings.

Main Results:

• The porcine mfERG trace exhibited three peaks (N1, P1, N2), similar to human responses.
• The visual streak showed significantly faster implicit times for N1 and increased amplitudes for all peaks compared to extra-visual streak areas.
• The laser-treated area demonstrated mfERG responses comparable to the optic nerve head, indicating a functional deficit.

Conclusions:

• Porcine mfERG is a viable technique, mirroring human electroretinographic patterns.
• The visual streak exhibits distinct, heightened electrophysiological activity compared to the optic nerve head and inferior retina.
• The established mfERG method successfully identified a localized functional deficit (3x3 mm) following induced laser injury.