Glaucoma severity affects diffusion tensor imaging (DTI) parameters of the optic nerve and optic radiation

Area of Science:

• Ophthalmology
• Neuroimaging
• Medical Physics

Background:

• Glaucoma is a progressive optic neuropathy characterized by damage to the optic nerve.
• Accurate assessment of glaucoma severity is crucial for effective management and treatment.
• Current methods for assessing glaucoma severity may have limitations in early detection and differentiation.

Purpose of the Study:

• To investigate the utility of Magnetic Resonance Imaging (MRI) Diffusion Tensor Imaging (DTI) in differentiating between mild and severe glaucoma.
• To determine if DTI-derived parameters of the optic nerve and optic radiation correlate with Retinal Nerve Fibre Layer (RNFL) thickness.

Main Methods:

• A 3-Tesla DTI scan was performed on 90 subjects (30 normal, 30 mild glaucoma, 30 severe glaucoma).
• Fractional Anisotropy (FA) and Mean Diffusivity (MD) of the optic nerve and optic radiation were measured.
• RNFL thickness was assessed using Optical Coherence Tomography (OCT); glaucoma severity was classified using the Hodapp-Parrish-Anderson (HPA) system.

Main Results:

• FA values decreased and MD values increased in the optic nerve and optic radiation with glaucoma progression.
• FA at the optic nerve demonstrated high sensitivity (87%) and specificity (80%) in discriminating glaucoma severity.
• FA values in the optic nerve showed the strongest correlation with RNFL thickness (r=0.684, p ≤ 0.001).

Conclusions:

• DTI-derived FA values in the optic nerve are sensitive and specific indicators of glaucoma severity.
• The strong correlation between DTI-FA and RNFL thickness supports its potential as a biomarker for glaucoma.
• DTI shows promise as a non-invasive tool for assessing glaucoma progression and severity.