Retinal oximetry in humans using visible-light optical coherence tomography [Invited]

Area of Science:

• Ophthalmology
• Biomedical Optics
• Medical Imaging

Background:

• Retinal oximetry is crucial for diagnosing various eye conditions.
• Visible-light optical coherence tomography (vis-OCT) offers a non-invasive method for retinal imaging.
• Accurate measurement of hemoglobin oxygen saturation (sO2) in retinal vessels is challenging due to signal noise.

Purpose of the Study:

• To develop and validate an improved vis-OCT technique for accurate retinal oximetry.
• To address the inherent signal-to-noise ratio limitations in human eye vis-OCT measurements.
• To establish a foundation for clinical application of vis-OCT-based retinal oximetry.

Main Methods:

• Hemoglobin oxygen saturation (sO2) was measured in the retinal circulation of healthy humans using vis-OCT.
• Theoretical and experimental analysis was performed to characterize noise in OCT intensity, identifying a Rice distribution.
• A novel statistical-fitting sampling strategy was employed to retrieve unbiased OCT intensity estimations.

Main Results:

• Oxygenation differences between central retinal arteries and veins were clearly detected near the optic nerve head.
• Spatial variations in oxygenation were observed at different vascular branching levels.
• The new statistical-fitting strategy reduced sO2 estimation error by three percentage points (pp).

Conclusions:

• The developed vis-OCT method provides accurate measurements of retinal hemoglobin oxygen saturation.
• The improved statistical approach enhances the reliability of vis-OCT oximetry.
• This work supports the clinical implementation of vis-OCT for retinal oxygenation assessment.