Optic disc blood perfusion and oxygenation in glaucoma

Area of Science:

• Ophthalmology
• Medical Imaging
• Glaucoma Research

Background:

• Glaucoma is a leading cause of irreversible blindness.
• Optic nerve damage in glaucoma is associated with vascular dysregulation.
• Quantifying optic disc hemodynamics is crucial for understanding glaucoma pathophysiology.

Purpose of the Study:

• To investigate and compare optic disc hemoglobin concentration and oxygenation between glaucoma patients and healthy controls.
• To assess the impact of neuronal activity stimulation on these parameters.
• To explore the correlation between optic disc hemodynamics and glaucoma severity.

Main Methods:

• Multispectral imaging was employed to measure optic disc reflectance at various wavelengths.
• Hemoglobin concentration and oxygenation (SO2) were calculated from reflectance data.
• Standard glaucoma diagnostic tools including perimetry, OCT, and OCT angiography were utilized.

Main Results:

• Glaucoma patients exhibited significantly lower optic disc hemoglobin concentration in both the rim and excavation compared to controls.
• While overall SO2 did not differ, a subgroup of glaucoma patients with ischemic disc rims showed reduced SO2.
• Hemoglobin concentration correlated significantly with visual field loss (perimetric mean defect), RNFL thickness, and perfusion density.

Conclusions:

• Optic disc hemoglobin concentration and oxygenation are quantifiable using multispectral imaging and are reduced in glaucoma.
• The observed reduction in hemoglobin concentration and its correlation with structural and functional parameters highlight its role in glaucoma pathology.
• These findings suggest that optic disc hemodynamics are a potential biomarker for glaucoma progression.