Retinal Oxygen Saturation during 100% Oxygen breathing in Healthy Subjects and Glaucoma Patients

Abstract

 

Purpose

 

Impaired regulation of retinal blood flow has been implicated in the pathophysiology of glaucoma. The purpose of the study was to test vascular regulation by evaluating the reaction to 100% oxygen breathing in retinal oxygen saturation and vessel diameter in patients with glaucoma and in healthy controls.

 

Methods

 

Retinal vessel oxygen saturation was measured in 11 patients with glaucoma and 16 healthy individuals with a fundus camera based oximeter, Oxymap T1. Oximetry was performed during breathing of room air, after ten minutes of breathing 100% oxygen and again during breathing of room air (10 minutes of recovery).

 

Results

 

In both groups, oxygen saturation was higher during breathing of 100% oxygen compared to room air in retinal arterioles (p=0.0011 in glaucoma, p<0.0001 in healthy) and venules (p<0.0001 in both groups), see figure. The arteriovenous difference was less during 100% oxygen breathing (p<0.0001 in both groups). Retinal vessel diameter decreased in both groups during 100% oxygen breathing in arterioles (p=0.0011 in glaucoma, p=0.0049 in healthy) and in venules (p<0.0001 in both groups). There was no statistically significant difference in oxygen saturation or vessel diameter between groups. This applies for both 100% oxygen and room air breathing (p>0.2). There was no statistically significant difference between the groups in vessel oxygen saturation change as well as in vessel diameter change from room air breathing to 100% oxygen breathing (see table). However, the oxygen saturation difference in venules from room air to 100% oxygen breathing was marginally higher in glaucoma patients (p=0.069).

 

Conclusions

 

Retinal oxygen saturation in arterioles and venules increased during hyperoxia in healthy subjects and glaucoma patients. Also, the vessel diameter decreased during hyperoxia in both groups. There is no significant difference in reaction to 100% oxygen breathing between healthy subjects and glaucoma patients.

 

 

The figure shows retinal oxygen saturation during breathing of room air and 100% oxygen breathing in both groups.

 

 

The table shows the change in vessel oxygen saturation and diameter from room air breathing to 100% oxygen breathing.

 

Keywords: 635 oxygen • 551 imaging/image analysis: non-clinical • 688 retina