Serial dual-wavelength illumination for retinal vessel oximetry using a conventional fundus camera: a...

Area of Science:

• Ophthalmology
• Biomedical Engineering
• Medical Imaging

Background:

• Retinal vessel oximetry is crucial for assessing oxygen saturation in the retina.
• Simultaneous dual-wavelength imaging can suffer from spectral crosstalk in one-chip fundus cameras.
• Multi-chip systems offer better spectral separation but are more complex.

Purpose of the Study:

• To present a serial dual-wavelength illumination approach integrated into a conventional fundus camera for retinal oximetry.
• To compare oxygen saturation measurements obtained with this novel method against a commercial retinal oximeter.
• To evaluate the feasibility and accuracy of serial illumination for retinal oximetry.

Main Methods:

• A custom LED illumination unit delivered serial light at 548 nm and 605 nm to a fundus camera.
• Images were acquired sequentially, registered, and analyzed using established retinal oximetry algorithms.
• Arterial and venous oxygen saturation were compared between the serial illumination method and a commercial oximeter in nine participants.

Main Results:

• Mean arterial oxygen saturation was 99.4% (serial) vs. 100.4% (commercial); venous was 71.5% vs. 69.5%.
• Mean absolute differences were 3.6% for arteries and 8.4% for veins.
• Arterial measurements showed a small bias (0.94%) and borderline correlation, while venous measurements had greater variability and no correlation.

Conclusions:

• Serial dual-wavelength illumination is a feasible technique for retinal vessel oximetry.
• This method effectively mitigates spectral crosstalk inherent in simultaneous imaging systems.
• Arterial measurements showed good agreement, but venous measurements require further optimization and validation for clinical use.