Abstract
Purpose :
To test, with different methods for retinal oximetry, if a change is detected over time in retinal oxygenation in diabetic retinopathy.
Methods :
Oximetry images of 214 patients with diabetic retinopathy were collected with the Oxymap T1 retinal oximeter in an outpatient clinic in Aarhus, Denmark. Imaging was repeated at subsequent patient visits. The Oxymap Analyzer 2.5.1 (ver.10981) was used for a single-blind, semi-automatic assessement of retinal vessel oxygen saturation. The same vessel segments were matched between visits. Different filtering, weigthing and averaging of the data was tested and compared. Automatic image quality assessment was also made with the Oxymap Analyzer software.
Results :
The median follow-up time was 3.0 years (min 0.8 years, max 6.8 years). Oxygen saturation in retinal arterioles increased from 95.9%±5.2% at the first visit to 97.6%±4.7% at the second visit (p<0.0001, standard analysis method). The corresponding numbers for venules were 67.9%±8.2% at the first visit and 71.9%±7.7% at the second visit (p<0.0001). Arteriovenous difference decreased from 27.9%±6.9% to 25.7%±6.5% (p<0.0001). The figure shows results of different analysis methods. Image quality grade at the first visit was 7.5±1.0 and 7.3±1.0 at the second (p=0.0027).
Conclusions :
All analysis methods showed an increase in arterial and venous saturation and a decrease in arteriovenous difference over time. Image quality decreased only slightly during the follow–up period. Semi-automatic analysis of large oximetry datasets is laborious and requires expertise. Ongoing development of automatic oximetry will help mitigate this. Oximetry results should be correlated to other clinical data for further understanding of changes with progression.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.