Abstract
Abstract: :
Purpose: To report an optical system that was established for noninvasive imaging of chorio-retinal oxygen tension. Due to its depth discrimination, this optical section imaging technique is capable of discrete imaging of oxygen tension in the chorio-retinal vasculatures. Methods: The method consists of projecting a narrow laser line at an angle on the retina following intravenous injection of an oxygen-sensitive probe and viewing phosphorescence emission. The probe (Pd porphine) phosphorescence emission is quenched by blood oxygen, and the degree of quenching is dependent on the concentration of oxygen near the probe molecule. Due to the angle between the incident laser and imaging path, a phosphorescence optical section image of the retina was captured. The system was tested in four rats, while breathing room air, 10% oxygen, 50% oxygen and after euthanasia when inhaled oxygen was near 0%. Linear regression analysis was applied to determine the correlation coefficient between oxygen-sensitive probe phosphorescence intensity and inhaled oxygen. Results: On the phosphorescence optical section image, retinal and choroidal vasculatures appeared laterally displaced according to their depth location, displaying probe phosphorescence discretely in the chorio-retinal vasculatures. The intensity of the phosphorescence decreased with increased degree of inhaled oxygen. The inverse of phosphorescence intensity and degree of inhaled oxygen were highly correlated (r = 0.9). Conclusion: The results demonstrate the feasibility of our technique for noninvasive and discrete imaging of oxygen-sensitive probe phosphorescence in the chorio-retinal vasculatures. The system has potential as a valuable tool for three-dimensional oxygen tension imaging and understanding disease-related oxygen dynamics in retinal, choroidal, and intra-retinal vasculatures.
Keywords: imaging methods (CT, FA, ICG, MRI, OCT, RTA, S • retina • hypoxia