July 2019
Volume 60, Issue 9
Open Access
ARVO Annual Meeting Abstract  |   July 2019
Validating Laser Speckle Contrast Imaging as a Quantitative Tool for Measuring Retinal Vascular Function in Rodents
Author Affiliations & Notes
  • Dwani Patel
    Cell Biology, Neurobiology, Anatomy, Medical College of Wisconsin, Milwaukee, Wisconsin, United States
  • Thomas B. Connor
    Department of Ophthalmology and Visual Science, Medical College of Wisconsin, Milwaukee, Wisconsin, United States
  • Daniel M. Lipinski
    Department of Ophthalmology and Visual Science, Medical College of Wisconsin, Milwaukee, Wisconsin, United States
    Nuffield Laboratory of Ophthalmology, University of Oxford, Oxford, United Kingdom
  • Footnotes
    Commercial Relationships   Dwani Patel, None; Thomas Connor, None; Daniel Lipinski, None
  • Footnotes
    Support  NEI 1R01EY027767-01A1, NIGMS T32-GM080202
Investigative Ophthalmology & Visual Science July 2019, Vol.60, 172. doi:
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    • Get Citation

      Dwani Patel, Thomas B. Connor, Daniel M. Lipinski; Validating Laser Speckle Contrast Imaging as a Quantitative Tool for Measuring Retinal Vascular Function in Rodents. Invest. Ophthalmol. Vis. Sci. 2019;60(9):172.

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      © ARVO (1962-2015); The Authors (2016-present)

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Abstract

Purpose : Rodent models of diabetes mellitus fail to develop the characteristic proliferative retinal vascular abnormalities of end-stage diabetic retinopathy – limiting their use for studying disease pathogenesis and the effectiveness of therapeutic interventions. Thus, developing methodologies to measure early changes in vascular function, which occur in small animal species like in humans, would significantly benefit the development of novel therapies. Using a rodent model of branch retinal vein occlusion (BRVO), here we evaluate whether laser speckle contrast imaging (LSCI), a non-invasive technique capable of visualizing hemodynamic changes with high spatiotemporal resolution, can be used to quantify changes in rodent retinal vascular function.

Methods : A commercial fundus camera (Phoenix Micron IV) was adapted to enable full field illumination of the mouse retina using a 640nm coherent laser light source and a speckle image analysis software was developed in Matlab. Using a syringe pump, blood was forced at various flow rates (0-2 mL/min) through polyethylene tubing (0.43mm ID) to evaluate our ability to quantify relative blood flow rate using ex vivo LSCI. Next, we performed LSCI in C57BL/6J mice (N=5) pre- and post-euthanasia to confirm that observed changes in speckle pattern derive from the movement of blood cells through the retinal vessels. Lastly, fluorescein angiography and LSCI were performed in age and gender-matched C57BL/6J mice (N=10) before and after (D1 and D7) BRVO induction using a 532nm diode laser.

Results : Speckle contrast intensity correlated with flow rate in our ex vivo capillary tubing and in vivo mouse models. Our imaging system and analysis software are capable of high spatial (~10μm) and temporal (≥10ms) resolution, enabling visualization and quantification of blood flow even in retinal microvessels. Pre- and post-euthanasia LSCI confirmed that change in contrast intensity derived solely from movement of blood through retinal vessels. LSCI of BRVO models showed a reduction in venous drainage and blood flow rate in occluded vessels relative to unaffected vessels.

Conclusions : LSCI can be applied to visualize and detect changes in rodent retinal vascular perfusion with high spatial and temporal resolution. LSCI may be useful for assessing early vascular changes in retinal diseases and as an outcome measure to determine therapeutic treatment efficacy.

This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.

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