Quantitative Retinal Vessel Oximetry in Ischaemic and Non-Ischaemic Retinal Vein Occlusion

Abstract

 

Purpose:

 

Hyperspectral imaging offers a non-invasive technique to measure the oxygen saturation in the retinal vasculature.This study aims to demonstrate the detection of oxygen saturation changes in the retinal vasculature of subjects with ischaemic and non-ischaemic retinal vein occlusion using quantitative analysis of hyperspectral retinal images.

 

Methods:

 

High resolution en face hyperspectral retinal images were obtained from subjects with angiographically confirmed ischaemic and non-ischaemic retinal vein occlusions using a modified conventional fundus camera.Algorithms incorporating physical optics models for light propagation within the retina were used to quantify the blood oxygen saturation along the retinal blood vessels and generate oximetric maps of the retinal vasculature of each subject.

 

Results:

 

In subjects with ischaemic retinal vein occlusion the quantitative retinal oximetry maps identified increased retinal venular oxygen saturation associated with areas of capillary non-perfusion. In subjects with non-ischaemic retinal vein occlusion the retinal venular oxygen saturation appears to be much lower than normal.

 

Conclusions:

 

Quantitative analysis of hyperspectral retinal images has the potential to detect oximetric changes in the retinal vasculature in ischaemic and non-ischaemic retinal vein occlusions. Increased venular oxygen saturation in ischaemic retinal vein occlusion may indicate either reduced metabolic consumption of oxygen in the inner retina or an arterio-venous shunting phenomenon within the retinal circulation. Reduced venular oxygen saturation in non-ischaemic retinal vein occlusion may indicate the consumption of residual venular oxygen diffusing out of stagnant retinal venules by functioning retinal tissues.  

 

Keywords: retina • imaging/image analysis: clinical • oxygen