Image-Guided Optical Coherence Tomography to Assess Structural Changes in Rodent Retinas

Summary

The protocol presented here details the procedures of data collection and data analysis for image-guided optical coherence tomography (OCT) and demonstrates its application in multiple rodent models of ocular diseases.

Abstract

Ocular diseases, such as age-related macular degeneration, glaucoma, retinitis pigmentosa, and uveitis, are always accompanied by retinal structural changes. These diseases affecting the fundus always exhibit typical abnormalities in certain cell types in the retina, including photoreceptor cells, retinal ganglion cells, cells in the retinal blood vessels, and cells in the choroidal vascular cells. Noninvasive, highly efficient, and adaptable imaging techniques are required for both clinical practice and basic research. Image-guided optical coherence tomography (OCT) satisfies these requirements because it combines fundus photography and high-resolution OCT, providing an accurate diagnosis of tiny lesions as well as important changes in the retinal architecture. This study details the procedures of data collection and data analysis for image-guided OCT and demonstrates its application in rodent models of choroidal neovascularization (CNV), optic nerve crush (ONC), light-induced retinal degeneration, and experimental autoimmune uveitis (EAU). This technique helps researchers in the eye field to identify rodent retinal structural changes conveniently, reliably, and tractably.

Introduction

Ocular diseases affecting the fundus always exhibit typical abnormalities in certain cell types in the retina, such as photoreceptor cells, retinal ganglion cells, cells in the retinal blood vessels, and cells in the choroidal blood vessels, which may subsequently influence the visual acuity of patients¹. To avoid irreversible visual impairment, timely diagnoses and appropriate treatments are required¹. Optical coherence tomography (OCT) has been widely used in the clinic to evaluate a range of ocular diseases, including age-related macular degeneration, retinitis pigmentosa, glaucoma, uveitis, and retinal detachment, am....

Protocol

All the animal procedures conformed to the Association for Research on Vision and Ophthalmology's statement on the Use of Animals in Ophthalmic and Vision Research and were approved by the Institutional Animal Care and Use Committee of Wenzhou Medical University (WMU). The rats and mice were given free access to water and food with an environmental light intensity of 18 lux on a 12 h dark/light cycle.

1. Preparation of the ocular animal models

1. Mouse laser-induced choroidal neovascularization (CNV) model^11,12
   1. Anesthetize 4-week-old female ....

Results

Image-guided OCT can be used to monitor the development of the laser spot in laser-induced choroidal neovascularization (CNV) in mice. As shown in Figure 1, the newborn blood vessels passed through Bruch's membrane as well as the retinal pigment epithelium (RPE) layer and formed a fibrotic scar after laser injury^11,12. This lesion spot could be captured under either full-size scanning (Figure 4A) or half.......

Discussion

This protocol provides instructions for the image collection and thickness measurement of image-guided OCT. By demonstrating the four most popular rodent models of ocular diseases, the researchers found that image-guided OCT provided excellent performance in examining drastic retinal structural alterations. In fact, with high-resolution images, tiny lesions can be found easily in OCT images as well. With the aid of image-guided OCT, a group in the laboratory also found abnormal hyperreflectivity spots within the OPL in a.......

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
BALB/c mouse	Beijing Vital River Laboratory Animal Technology Co., Ltd		Animal model preparations
C57BL/6JNifdc mouse	Beijing Vital River Laboratory Animal Technology Co., Ltd		Animal model preparations
Carbomer Eye Gel	Fabrik GmbH Subsidiary of Bausch & Lomb		Moisten the cornea
Complete Freund’s adjuvant	Sigma	F5881	EAU experiment
Experimental platform	Phoenix Technology Group		Animal model preparations
hIRBP161-180	Shanghai Sangon Biological Engineering Technology & Services Co., Ltd.		EAU experiment
Ketamine	Ceva Sante Animale		General anesthesia
Laser box	Haag-Streit Group	Merilas 532α	Animal model preparations
Lewis rat	Beijing Vital River Laboratory Animal Technology Co., Ltd		Animal model preparations
Mycobacterium Tuberculosis H37RA	Sigma	344289	EAU experiment
Phoneix Micron IV with image-guided OCT and image-guided laser	Phoenix Technology Group		Animal model preparations
Tissue forceps	Suzhou Mingren Medical Instrument Co., Ltd	MR-F101A-5	Animal model preparations
Tropicamide Phenylephrine Eye Drops	SANTEN OY, Japan		Eye dilatation
Vannas scissors	Suzhou Mingren Medical Instrument Co., Ltd	MR-S121A	Animal model preparations
Xylazine	Ceva Sante Animale		General anesthesia