[Impairment of the Visual System in Glaucoma]

Area of Science:

• Ophthalmology
• Neuroscience
• Radiology

Background:

• Glaucoma is characterized by optic nerve damage and visual field loss.
• Optic radiation atrophy is more pronounced in glaucoma patients compared to controls.
• This atrophy correlates with Optical Coherence Tomography (OCT) and visual field test results.

Purpose of the Study:

• To investigate the utility of advanced Magnetic Resonance Imaging (MRI) techniques in visualizing and quantifying visual system changes in glaucoma.
• To explore the potential of Diffusion Tensor Imaging (DTI) and metabolic MRI in understanding the neurodegenerative processes in glaucoma.

Main Methods:

• Diffusion Tensor Imaging (DTI) was used to assess axonal integrity of the optic radiation by calculating fractional anisotropy (FA) and radial diffusivity (RD).
• Metabolic MRI, utilizing specific Na+-coils and Chemical Exchange Saturation Transfer (CEST) techniques, was employed to visualize neuronal cell death and protein accumulation.
• Changes in FA and RD, both within and outside the visual system, were analyzed.

Main Results:

• Glaucoma patients exhibit more pronounced atrophy of the optic radiation than age-matched controls.
• DTI-derived measures (FA and RD) show substantial changes, suggesting a complex neurodegenerative disease process.
• Metabolic MRI techniques offer potential for visualizing neuronal damage and pathological protein accumulation.

Conclusions:

• Glaucomatous atrophy of the visual system may result from antero- and retrograde axonal degeneration.
• Retrograde degeneration in specific glaucoma types (normal tension, PEX) can be linked to ischemic lesions or protein accumulation.
• Advanced MRI, including DTI and metabolic imaging, holds promise for improved diagnosis and therapeutic monitoring in glaucoma.