Retinal tissue oxygen tension imaging in the rat

Area of Science:

• Ophthalmology
• Biomedical Engineering
• Physiology

Background:

• Retinal oxygen tension (PO2) is critical for visual function and is affected by various ocular diseases.
• Accurate measurement of retinal PO2 is essential for understanding retinal physiology and pathology.
• Current methods for measuring retinal PO2 are limited in their ability to provide quantitative, spatially resolved data.

Purpose of the Study:

• To develop and validate an imaging technique for quantitative measurement of retinal oxygen tension (PO2).
• To assess the feasibility of this technique for measuring retinal PO2 variations in rat eyes.
• To investigate the impact of adjusting the fraction of inspired oxygen (FiO2) on retinal PO2.

Main Methods:

• An oxygen-sensitive molecular probe was injected intravitreally.
• A narrow laser line projected onto the retina, and phosphorescence emission was imaged.
• A frequency-domain approach measured phosphorescence lifetime to compute retinal PO2 maps and depth profiles under varying FiO2 (10%, 21%, 50%).

Main Results:

• The developed imaging technique provided repeatable retinal PO2 measurements.
• Significant differences in outer retinal PO2 were observed across different FiO2 levels (P<0.0001).
• Outer retinal PO2 showed strong correlations with systemic arterial PO2 (R=0.70) and inner retinal PO2 (R=0.88).

Conclusions:

• A novel, quantitative imaging technique for mapping retinal tissue oxygen tension has been successfully developed.
• This technique demonstrates feasibility for sequential monitoring of retinal oxygenation.
• The method holds potential for applications in studying retinal oxygenation in both healthy and diseased states.