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Visual Pathways Involvement in Friedreich's Ataxia Patients Without Macular Impairment
Vincenzo Parisi1,2, Lucilla Barbano1, Antonio Di Renzo1
1IRCCS-Fondazione Bietti, Via Livenza 3, 00198 Rome, Italy.
Journal of Clinical Medicine
|August 13, 2026
Summary
Friedreich Ataxia (FA) patients exhibit impaired retinal ganglion cell (RGC) function and post-retinal visual pathway conduction. This neural conduction deficit is more pronounced in late-onset FA and is not linked to patient age or disease onset age.
Area of Science:
- Neuroscience
- Ophthalmology
- Genetics
Background:
- Friedreich Ataxia (FA) is a rare inherited disease.
- Visual Evoked Potential (VEP) abnormalities in FA suggest potential issues with retinal ganglion cells (RGCs) or post-retinal visual pathways.
- Clarifying the exact location of visual pathway dysfunction in FA is crucial for understanding disease progression.
Purpose of the Study:
- To determine if abnormal neural conduction in FA involves dysfunctional RGCs, impaired post-retinal pathways, or both.
- To investigate the relationship between RGC and/or post-retinal dysfunction and patient age, age at disease onset, and disease duration.
Main Methods:
- Simultaneous pattern electroretinogram (PERG) and VEP recordings were performed on 14 FA patients and 20 healthy controls.
- Retino-cortical time (RCT) was calculated by measuring the difference between VEP P100 and PERG P50 implicit times.
- Patients were categorized into early-onset (FA2) and late-onset (FA1) groups based on disease onset age.
Main Results:
- FA patients showed significantly reduced PERG amplitude and significantly delayed VEP implicit times compared to controls.
- Increased RCT values were observed in FA patients, particularly in the late-onset (FA1) group.
- No significant correlation was found between electrophysiological parameters and age at disease onset in late-onset FA patients.
Conclusions:
- Both RGC function and neural conduction along post-retinal visual pathways are impaired in the studied FA population.
- Abnormal neural conduction is more severe in late-onset FA patients.
- Disease duration has a minor impact on post-retinal neural conduction in small optic nerve fibers.
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