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Wouter Vehmeijer, Sveinn Hakon Hardarson, Kelly Jonkman, Albert Dahan, Leon Aarts, Einar Stefansson, Nicoline Schalij-Delfos; Handheld and mobile oximeter in a healthy adult population. Invest. Ophthalmol. Vis. Sci. 2017;58(8):3125.
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© ARVO (1962-2015); The Authors (2016-present)
The purpose of this study is to introduce a prototype handheld and mobile retinal oximeter (Corimap) for clinical research. Dual wavelength retinal oximetry is a method to measure the relative oxygen saturation in the retinal vessels, utilizing the difference in light absorption of hemoglobin bound and unbound to oxygen.The novel feature of handheld oximeter is that images can be captured in sitting and supine patients. The objective of this study is to measure the Optical Density Ratio (ODR) of the Corimap oximeter in both upright and supine position. For comparison, the ODR was also measured with an Oxymap T1 oximeter.
For this study, healthy volunteers (age 18-35) were recruited at the Leiden University Medical Center. After mydriasis, retina images were acquired with both Corimap Camera and Oxymap T1. The Oxymap T1 is a fundus camera based oximeter and the newly developed mobile Corimap camera is a handheld oximeter. Both dual wavelength oximeters acquire images in 570nm and 600nm. For the Corimap camera, images were captured in sitting and supine position. Images were processed by Oxymap Analyzer software for the calculation of ODR. The ODR has an approximately linear inverse relationship to oxygen saturation. A paired t–test was used for statistically analysis.
In this study, healthy subjects (n = 11, mean age 25±1.9 years) were included for the measurement of ODR. For the Corimap camera, the ODR of arterioles was upright 0.217±0.044 and for the venules 0.533±0.100. In supine position the ODR for arterioles was 0.244±0.107 and for the venules 0.486±0.130. For the Oxymap T1, the ODR was 0.204±0.033 for arterioles and 0.499±0.064 for venules. In all cases, a paired t-test showed a statistical significant difference in the ODR of arterioles and venules (p<0.005). The ODR values of the Corimap camera did not differ statistically in sitting or supine position (p>0.05) neither did the ODR measurements between the Corimap oximeter and the Oxymap T1 oximeter (p>0.05).
With the introduction of this novel mobile and handheld oximeter, retinal oximetry will be applicable in a broader variety of diseases and patient populations. The Corimap measures the ODR and the retinal vessel oxygen saturation in sitting and supine patients.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.
Figure 1. A retinal image of a supine subject processed by the Oxymap Analyzer software for the calculation of the hemoglobin oxygen saturation of the retinal arterioles and venules.
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