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EC Ophthalmol. 2017;5(3):89-98. Epub 2017 Feb 21.

OCT-Angiography for Non-Invasive Monitoring of Neuronal and Vascular Structure in Mouse Retina: Implication for Characterization of Retinal Neurovascular Coupling.

Author information

1
Ophthalmology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China.
2
Department of Ophthalmology and Visual Sciences, University of Texas Medical Branch, Galveston, TX, United States.
3
Department of Pharmacology and Toxicology, University of Texas Medical Branch, Galveston, TX, United States.
4
Center for Biomedical Engineering, University of Texas Medical Branch, Galveston, TX, United States.
5
Department of Neuroscience and Cell Biology, University of Texas Medical Branch, Galveston, TX, United States.

Abstract

Purpose:

Optical coherence tomography angiography (OCT-A) is a newly developed technique to visualize retinal vasculature non-invasively based on interferometry. Although OCT-A has been used clinically, its applications in small animal studies have been limited. This study is designed to develop and demonstrate the feasibility of a protocol for the use of an en-face OCT-based method to visualize and quantify retinal microvasculature in mice that can be used for in vivo assessment of retina ischemia.

Methods:

A customized algorithm was developed to extract angiographic profiles of the mouse retina from en-face OCT using an unmodified Bioptigen Envisu R-Class OCT imaging system. En-face OCT images were collected in living animals and then compared to images acquired following termination of blood flow to the retina. The images were processed with ImageJ using the raw file importer. The vessel enhancement algorithm was developed based on a combination of local contrast enhancement, Laplacian of Gaussian peak detection and background subtraction methods. For comparison, fluorescein angiography (FA) was performed using Heidelberg Spectralis® HRA+OCT imaging system.

Results:

By vessel enhancement algorithm, we successfully extracted retinal vasculature and quantified retinal vessel branch points, vascular area and vessel lengths with AngioTool. While the retinal neuronal structure could be simultaneously identified and quantified using B-scan and volumetric OCT run in the annular scanning model, the retinal vasculature in OCT-A was dramatically diminished after the animals were sacrificed, indicating en-face OCT-A signal is a measure of the blood flow.

Conclusions:

These studies indicate that a novel approach to extract angiographs from en-face OCT images by utilizing local structure enhancement can be used to provide depth-resolved retinal vasculature distributions. Simultaneous non-invasive analysis of retinal vessels and neurons by OCT-A and OCT may provide a novel approach to characterize retinal ischemia accompanied by neurovascular coupling.

KEYWORDS:

Mouse; Neuron; OCT Angiography (OCT-A); Optical Coherence Tomography (OCT); Retina; Vasculature

PMID:
29333536
PMCID:
PMC5766278

Conflict of interest statement

Conflict of Interest The authors state that the manuscript has not been published previously. Copyright application of the software patch to conduct OCT-A analysis is pending approval.

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