Morphometric analyses of the visual pathways in macular degeneration

TL;DR

This study reveals that macular degeneration leads to structural degeneration along the entire visual pathway, with distinct patterns in age-related and juvenile forms, and links AMD to frontal white matter reduction and potential cognitive decline.

Contribution

It provides the first comprehensive morphometric analysis of visual pathway structures in both AMD and JMD, highlighting disease-specific neurodegenerative patterns.

Findings

Volumetric reductions in optic nerves, chiasm, lateral geniculate bodies, optic radiations, and visual cortex in JMD.

Reductions in lateral geniculate bodies, optic radiations, and visual cortex in AMD.

AMD associated with frontal white matter volume reduction, suggesting links to cognitive impairment.

Abstract

Introduction. Macular degeneration (MD) causes central visual field loss. When field defects occur in both eyes and overlap, parts of the visual pathways are no longer stimulated. Previous reports have shown that this affects the grey matter of the primary visual cortex, but possible effects on the preceding visual pathway structures have not been fully established. Method. In this multicentre study, we used high-resolution anatomical magnetic resonance imaging and voxel-based morphometry to investigate the visual pathway structures up to the primary visual cortex of patients with age-related macular degeneration (AMD) and juvenile macular degeneration (JMD). Results. Compared to age-matched healthy controls, in patients with JMD we found volumetric reductions in the optic nerves, the chiasm, the lateral geniculate bodies, the optic radiations and the visual cortex. In patients with AMD we found volumetric reductions in the lateral geniculate bodies, the optic radiations and the visual cortex. An unexpected finding was that AMD, but not JMD, was associated with a reduction in frontal white matter volume. Conclusion. MD is associated with degeneration of structures along the visual pathways. A reduction in frontal white matter volume only present in the AMD patients may constitute a neural correlate of previously reported association between AMD and mild cognitive impairment. Keywords: macular degeneration - visual pathway - visual field - voxel-based morphometry