Evaluation of Visual Cortex Activity Using Functional Near-Infrared Spectroscopy in Primary Open Angle and Primary...

Area of Science:

• Neuroscience
• Ophthalmology
• Medical Imaging

Background:

• Glaucoma, a leading cause of irreversible blindness, involves progressive optic nerve damage.
• Visual cortex dysfunction is increasingly recognized in glaucoma, but its assessment remains challenging.

Purpose of the Study:

• To evaluate visual cortex activity using functional near-infrared spectroscopy (fNIRS) in patients with primary open-angle glaucoma (POAG) and primary angle-closure glaucoma (PACG).
• To compare visual cortex activity between glaucoma patients and healthy controls.
• To investigate the correlation between visual cortex activity and glaucoma severity.

Main Methods:

• A cross-sectional observational pilot study involving 30 POAG patients, 31 PACG patients, and 30 age-matched healthy controls.
• fNIRS was employed to measure changes in oxyhemoglobin (OxyHb) concentration in the visual cortex during a visual stimulus.
• Visual cortex activity was quantified by the maximum amplitude of OxyHb change over 10 seconds.

Main Results:

• Both POAG and PACG groups exhibited significantly lower visual cortex activity compared to controls in the middle occipital gyri.
• No significant difference in visual cortex activity was found between POAG and PACG groups.
• Glaucoma patients showed a negative correlation between visual cortex activity and visual field defect severity (mean deviation) and a positive correlation with retinal nerve fiber layer thickness.

Conclusions:

• Patients with glaucoma demonstrate reduced visual cortex activity, potentially indicating neuronal degeneration in the occipital cortex.
• Visual cortex activity is closely correlated with glaucoma disease severity.
• fNIRS is a promising neuroimaging tool for assessing hemodynamic and neurodegenerative changes in glaucoma.