Molecular imaging reveals unique degenerative changes in experimental glaucoma.

Area of Science:

• Neuroscience
• Ophthalmology
• Medical Imaging

Background:

• Glaucoma is a leading cause of irreversible blindness.
• Early diagnosis and intervention are crucial for preserving vision.
• Understanding the central visual pathway's response to glaucoma is vital.

Purpose of the Study:

• To investigate changes in the central visual pathway in experimental unilateral glaucoma using positron emission tomography (PET).
• To evaluate the utility of PET imaging as a tool for early glaucoma diagnosis and identifying neural degeneration.

Main Methods:

• Monkeys with experimentally induced unilateral hypertension glaucoma underwent PET scans.
• 2-[18F]fluoro-2-deoxy-glucose (FDG) PET was used to assess neural activity during monocular visual stimulation.
• [11C]PK11195 PET and immunohistochemistry were employed to detect neuroinflammation and microglial activation.

Main Results:

• Monocular stimulation of the affected eye showed significantly reduced neural responses in the ipsilateral occipital visuocortical areas.
• Activated microglia, indicative of neural degeneration, were observed bilaterally in the lateral geniculate nuclei.
• PET imaging demonstrated the unique vulnerability of the ipsilateral visual cortex in experimental glaucoma.

Conclusions:

• Noninvasive molecular imaging, particularly PET, is useful for the early diagnosis of glaucoma.
• PET provides a sensitive surrogate endpoint for detecting early-stage glaucoma and associated neural degeneration.
• The findings highlight the specific impact of unilateral glaucoma on the visual cortex and lateral geniculate nuclei.