Diffusion Tensor Imaging of Visual Pathway Abnormalities in Five Glaucoma Animal Models

Area of Science:

• Neuroscience
• Ophthalmology
• Medical Imaging

Background:

• Glaucoma is a leading cause of irreversible blindness.
• Understanding visual pathway damage in glaucoma is crucial for developing effective treatments.
• Diffusion tensor imaging (DTI) offers a non-invasive method to assess white matter integrity.

Purpose of the Study:

• To characterize visual pathway integrity in five distinct glaucoma animal models.
• To evaluate the utility of diffusion tensor imaging (DTI) in detecting microstructural changes in the optic nerve and optic tract.
• To compare DTI findings across experimentally induced and genetically determined glaucoma models.

Main Methods:

• Evaluated two inducible (microbead, laser) and three genetic (DBA/2J, LTBP2 mutant, TBK1) glaucoma models.
• Measured DTI parameters: fractional anisotropy (FA), axial diffusivity (AD), and radial diffusivity (RD) along the optic nerve and tract.
• Compared DTI metrics between glaucoma models and their respective healthy controls.

Main Results:

• Elevated intraocular pressure (IOP) was confirmed in all models except transgenic TBK1 mice.
• Significantly reduced FA and increased RD were observed in inducible and genetic glaucoma models (excluding TBK1).
• DBA/2J mice showed reduced AD, while TBK1 mice exhibited no significant DTI changes compared to controls.

Conclusions:

• Chronic IOP elevation leads to decreased FA and increased RD in visual pathways, indicating microstructural disruption.
• DTI is effective in characterizing visual pathway damage in various glaucoma models.
• Axial diffusivity changes vary across models, suggesting differential pathological processes.