Progression of Visual Pathway Degeneration in Primary Open-Angle Glaucoma: A Longitudinal Study

Area of Science:

• Neuroscience
• Ophthalmology
• Radiology

Background:

• Primary open-angle glaucoma (POAG) is associated with widespread white matter (WM) degeneration in visual pathways.
• The origin and spread pattern of this WM degeneration (pre- vs. post-geniculate) remain unclear.

Purpose of the Study:

• To longitudinally assess WM degeneration progression in the pre-geniculate optic tracts (OTs) and post-geniculate optic radiations (ORs) of POAG patients.
• To determine the source and pattern of spread of glaucomatous WM degeneration.

Main Methods:

• Diffusion-weighted MRI scans were acquired from 12 POAG patients and 14 controls at two time-points (5.4 ± 2.1 years apart).
• Fiber density (FD), an indicator of WM axonal density, was computed for OTs and ORs.
• Longitudinal analysis compared FD between groups and assessed changes over time.

Main Results:

• POAG patients showed significantly lower FD in OTs and ORs compared to controls at both time-points.
• POAG patients exhibited significant FD loss in the right OT and both ORs over time.
• The left OR showed a significantly higher rate of FD loss in POAG patients compared to controls.

Conclusions:

• Longitudinal neurodegenerative WM changes progress in both pre- and post-geniculate visual pathways in POAG.
• Glaucomatous WM degeneration appears to originate in pre-geniculate pathways and subsequently spread to post-geniculate pathways.
• There is a potential therapeutic window for targeting intact post-geniculate pathways, even with ongoing degeneration.