Diffusion Tensor Imaging Detects Microstructural Differences of Visual Pathway in Patients With Primary Open-Angle...

Area of Science:

• Neuroimaging
• Ophthalmology
• Medical Physics

Background:

• Ocular hypertension (OHT) affects ~5% of adults globally.
• Differentiating early primary open-angle glaucoma (POAG) from OHT is challenging with current methods.
• Diffusion tensor imaging (DTI) offers potential for assessing visual pathway axonal integrity.

Purpose of the Study:

• To evaluate the efficacy of high-resolution DTI in differentiating POAG from OHT.
• To investigate DTI parameters (FA and MD) in the optic tract (OT), lateral geniculate body (LGN), and optic radiation (OR).
• To correlate DTI findings with morphological and functional ophthalmological measurements.

Main Methods:

• Recruited 32 POAG patients (15 OHT, 14 controls), with 62.5% of glaucoma cases in early stages.
• Performed standard ophthalmological assessments including automated perimetry and OCT.
• Applied voxel-based analysis of DTI to measure fraction anisotropy (FA) and mean diffusivity (MD) in the OT, LGN, and OR.

Main Results:

• Significantly lower FA values in bilateral optic radiation (OR) were observed in POAG compared to OHT patients.
• Higher mean diffusivity (MD) values in the right lateral geniculate body (LGN) were found in POAG patients versus OHT subjects.
• No significant differences in DTI parameters were found between OHT and control groups.
• DTI parameters showed positive correlations with morphological (VCDR) and functional (MDVF) measurements in POAG patients.

Conclusions:

• DTI effectively differentiates POAG from OHT, particularly in early stages, by analyzing visual pathway microstructural changes.
• DTI parameters correlate with established clinical measures of glaucoma severity.
• DTI shows promise for quantifying the progression of POAG.