Time-dependent diffusion tensor changes of optic nerve in patients with indirect traumatic optic neuropathy

Area of Science:

• Neuroimaging
• Ophthalmology
• Neurology

Background:

• Indirect traumatic optic neuropathy (ITON) causes irreversible vision loss due to axonal degeneration.
• Conventional imaging cannot assess axonal damage in ITON.
• Diffusion tensor imaging (DTI) offers a non-invasive method to evaluate axonal integrity.

Purpose of the Study:

• To investigate time-dependent changes in ITON using DTI.
• To provide imaging evidence for ITON diagnosis and treatment.

Main Methods:

• 28 unilateral ITON patients underwent ocular examinations and MRI.
• Optic nerves (ON) were compared between injured and contralateral sides.
• Patients were grouped by time post-injury: <7 days, 7-30 days, >30 days.
• DTI parameters were analyzed, correlating with retinal nerve fiber layer (RNFL) and ganglion cell complex (GCC) thickness.

Main Results:

• Reduced fractional anisotropy (FA) in injured ON observed at 7-30 days.
• Further reductions in FA, axial diffusivity (λ//), and increases in radial diffusivity (λ┴) and mean diffusivity (MD) noted after 30 days.
• Progressive decrease in FA and increase in λ┴ over time.
• Increased MD and λ┴ correlated with RNFL and GCC thinning; FA correlated with RNFL thickness.

Conclusions:

• DTI parameters serve as effective biomarkers for detecting optic nerve changes in ITON.
• DTI can aid in the clinical diagnosis and management of ITON.