Scattering process in LDV from retinal vessels

Area of Science:

• Ophthalmology
• Biomedical Engineering
• Laser Physics

Background:

• Accurate measurement of retinal blood flow is crucial for diagnosing and monitoring various ocular diseases.
• Laser Doppler velocimetry (LDV) offers a non-invasive method for assessing blood flow dynamics.
• Understanding the optical properties of retinal vessels is essential for refining LDV techniques.

Purpose of the Study:

• To apply Laser Doppler Velocimetry (LDV) for measuring blood flow in small retinal vessels (<120 microm) of a cat.
• To investigate the influence of laser light transmission pathways on Doppler shift power spectra.
• To validate theoretical models of blood flow in retinal vasculature.

Main Methods:

• Utilized a linearly polarized Helium-Neon (He-Ne) laser as the incident beam for LDV.
• Performed measurements on retinal vessels in a feline model.
• Analyzed Doppler shift power spectra to assess red blood cell velocity profiles.

Main Results:

• Successfully obtained Doppler shift power spectra from retinal vessels.
• Demonstrated that preventing double transmission of laser light is critical for accurate measurements.
• Observed that under single transmission conditions, spectra matched theoretical predictions for a parabolic velocity profile.

Conclusions:

• Laser Doppler velocimetry is a viable technique for measuring blood flow in small retinal vessels.
• The single scattering model accurately predicts Doppler shift power spectra when double transmission is avoided.
• These findings support the use of LDV for in-vivo retinal blood flow analysis.