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Marielle Mentek, Christophe Chiquet, Frederic Truffer, Mario Bernabei, Benjamin Mottet, Jean-Paul Romanet, Diane Godin-Ribuot, Martial Geiser; Development of a prototype of laser Doppler flowmeter for the measurement of blood flow of retinal vessels and optic nerve head tissue in small animals (rats). Invest. Ophthalmol. Vis. Sci. 2013;54(15):4669.
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© ARVO (1962-2015); The Authors (2016-present)
The aim of the present study was to validate a new laser Doppler flowmeter (LDF) device, specifically designed to measure retinal and optic nerve head blood flow in the rat. We investigated the reproducibility of blood flow parameters measurements on optic nerve head and retinal arteries in Wistar rats along with the effects of hyperoxia.
Rats were immobilized on a modified stereotactic table, which allows free rotation of the instrument around the eye, in order to aim the probing beam on the fundus. The fundus is illuminated with a green light and an image is captured with a CCD for easy targeting (measurement diameter about 60 μm). In vivo validation consisted of: (1) Study of linearity of the instrument with a rotating diffusing wheel. (2) Measurement reproducibility during a single experimental session (n = 5 rats, 1 hour, 4 measurements of 5-min duration) by calculation of intra-individual Variation Coefficients (VC) and Intra-class Correlation Coefficient (ICC). (3) Blood Flow (BF), velocity (Vel) and volume (Vol) (mean ± SD) were evaluated in response to 100% oxygen breathing (n = 8 rats).
Vel varied linearly with the rotating speed (R2=0.9806) while Vol did not change (standard deviation/mean = 2.9%). Short-term reproducibility of retinal arterial Vel shows strong agreement (ICC=0.9, IC 95%=0.7-0.99), associated with low intra-individual VC (7.8 ± 6.6 %). After 2 minutes of 100% oxygen breathing, retinal arterial Vel was significant decreased by 17.0 ± 13.7 % (p=0.012), and optic nerve head BF by 11.0 ± 9.7 % (p=0.018).
This new LDF device allows repeatable measurements of ocular blood flow in small animals. Rat optic nerve head and retinal blood flow measurements are of crucial interest in physiological and pathophysiological studies. This prototype will be used to investigate various animal models (diabetes mellitus, glaucoma, vascular disorders) and for therapeutic evaluation.
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