Transhemispheric optic pathway degeneration following unilateral post-geniculate lesions

Area of Science:

• Neuroscience
• Ophthalmology
• Radiology

Background:

• Unilateral post-geniculate optic pathway lesions cause contralateral visual hemifield loss.
• Degeneration in ipsilesional optic tracts and retinas is known.
• Contralesional degeneration in the post-chiasmal optic pathway is understudied.

Purpose of the Study:

• To investigate the presence and extent of contralesional degeneration in individuals with unilateral post-geniculate optic pathway lesions.
• To evaluate white matter integrity in optic pathway tracts using advanced imaging analysis.

Main Methods:

• Case-control study design.
• Fixel-based analysis of diffusion-weighted imaging data.
• Examination of two cohorts with unilateral post-geniculate lesions and healthy controls.

Main Results:

• Reduced fibre density and fibre-bundle cross-section observed in both ipsilesional and contralesional optic pathways.
• Further degeneration noted in the forceps major.
• Evidence of widespread transhemispheric degeneration beyond the primary lesion site.

Conclusions:

• Unilateral post-geniculate optic pathway lesions induce degeneration extending to contralesional tracts.
• This pattern of degeneration is more extensive than previously understood.
• Further research is needed to understand the functional implications of this widespread degeneration for vision.