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Martin Vietauer, René M Werkmeister, Corinna Knopf, Walthard Vilser, Leopold Schmetterer; Measurement of relative blood flow changes in retinal vessels of rodents by a Doppler FD-OCT system with integrated dynamic vessel analyzer. Invest. Ophthalmol. Vis. Sci. 2014;55(13):4326.
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© ARVO (1962-2015); The Authors (2016-present)
To determine whether Doppler Fourier-domain optical coherence tomography (FD-OCT) in combination with dynamic retinal vessel analysis allows for detection of blood flow changes due to administration of different breathing gases in vivo in rodent’s retinal vessels, and, thus, for study of ocular diseases in animal models.
For blood flow measurements a single beam FD-OCT system with a center wavelength of 841 nm, a spectral bandwidth of 49.6 nm and a frame rate of 20 Hz has been combined with a commercially available retinal vessel analyzer (RVA) for rodents by Imedos GmbH (Jena, Germany). The FD-OCT system is capable of measuring relative velocities in retinal vessels while the RVA provides high resolution data of retinal vessel diameters. The combination of those two systems and the simultaneous measurement of the velocity and the retinal vessel diameters enable the calculation of the relative blood flow. The rodents were sedated and breathed air for 10 minutes; afterwards the breathing gas was switched to 100 % oxygen for another 10 minutes. In each animal, one major vein was measured at a distance of about one disc diameter from the optic nerve head. While vessel diameters were recorded continuously during the whole session starting at minute 8 of the air breathing phase, blood flow velocity measurements were carried out at the minutes 8 and 9 of the air breathing phase (baseline) and at the minutes 2, 4, 6, 8, 9 and 10 of the oxygen breathing phase. OCT recordings lasted 14s to allow for averaging of the phase data and calculation of the mean velocity.
Based on the baseline measurements we observed a decrease of the venous velocity, diameter and consequently the venous blood flow due to the oxygen breathing in all test animals. The decrease of the vessels’ velocity was ranging from -38 % to -50 %, while a vasoconstriction of -8 % to -20 % was measured, and, the resulting decrease of the venous blood flow of -45 % to -64 % was determined.
The significant oxygen induced decrease of the venous retinal blood flow is an excellent confirmation for the system’s functionality. The system is well suited for the study of various ocular vascular diseases in animal models.
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