Electroretinographic oscillatory potentials in Leber hereditary optic neuropathy

Area of Science:

• Ophthalmology
• Neuroscience
• Genetics

Background:

• Leber hereditary optic neuropathy (LHON) is a genetic disorder causing severe vision loss due to retinal ganglion cell degeneration.
• Standard electroretinogram (ERG) measures like the photopic negative response (PhNR) are often affected in LHON.
• Investigating high-frequency components of the ERG, such as oscillatory potentials (OPs), may offer deeper insights into LHON pathophysiology.

Purpose of the Study:

• To evaluate dark-adapted (DA) and light-adapted (LA) oscillatory potentials (OPs) in the flash ERG of genetically confirmed LHON patients.
• To differentiate slow from fast neuronal response components in LHON using specific ERG parameters.
• To explore the potential of OPs as functional biomarkers for LHON status.

Main Methods:

• Full-field ERGs were recorded from seven LHON patients and twelve healthy controls.
• Digital filters with low cutoff frequencies of 50, 75, and 100 Hz were applied to isolate high-frequency ERG components.
• Specific OP components (OP2, OP3, OP4) were analyzed for amplitude differences between groups under DA and LA conditions.

Main Results:

• ERG a-waves and b-waves were similar between LHON patients and controls.
• Photopic negative response (PhNR) was significantly reduced in LHON patients.
• Reduced peak amplitude of dark-adapted OP2 was observed in LHON patients (75 Hz cutoff).
• Light-adapted OPs (OP2, OP3, OP4) showed significant differences between LHON patients and controls with a 100 Hz cutoff filter.

Conclusions:

• Reduced OPs in LHON suggest impaired neuronal interactions in the inner retina, despite preserved photoreceptor and bipolar cell function.
• Dark-adapted OP2 reduction and light-adapted OP alterations with high-frequency filtering may serve as functional indicators for LHON.
• Further research into these OP alterations could enhance the characterization and monitoring of LHON progression.