Multifocal, pattern and full field electroretinograms in cats with unilateral optic nerve section

Area of Science:

• Neuroscience
• Ophthalmology
• Visual Electrophysiology

Background:

• The optic nerve head is crucial for visual signal transmission.
• Understanding electroretinogram (ERG) components helps diagnose optic nerve dysfunction.
• Multifocal ERGs (mFERGs) offer localized retinal responses.

Purpose of the Study:

• To identify a subcomponent of the mFERG originating at the optic nerve head.
• To investigate if this mFERG component's latency increases with distance from the optic nerve head.
• To compare mFERG and multifocal pattern ERG (mPERG) changes with full-field ERGs after optic nerve section in cats.

Main Methods:

• Recorded mFERGs and mPERGs in cats with unilateral optic nerve section.
• Utilized three intensity levels for mFERGs and recorded responses across 61 areas.
• Compared responses between normal and denervated eyes, analyzing latency variations relative to the optic nerve head.

Main Results:

• No mFERG component was found to vary in latency with distance from the optic nerve head.
• Localized changes near OP2 were observed in the mFERG, potentially related to ganglion cell density variations.
• Full-field PERGs and FERGs showed significant reductions, with mesopic OPs most affected.

Conclusions:

• The cat mFERG lacks a component whose latency varies with distance from the optic nerve head.
• Observed mFERG changes were qualitatively similar to light-adapted full-field ERGs.
• The study suggests local variations in ganglion cell density may explain some observed mFERG alterations.