Name: In Vivo Visible Light Optical Coherence Tomography (OCT) Mouse Retinal Imaging
Uploaded: 2023-06-30T13:00:00
Description: Watch this Scientific Journal Video about In Vivo Visible Light Optical Coherence Tomography OCT Mouse Retinal Imaging at JoVE.com

in vivo visible light optical coherence tomography (oct) mouse retinal imaging

Mouse Retina OCT Fibergram Alignment with Confocal Images

Retinal ganglion cells (RGCs) play a critical role in visual information processing, receiving synaptic inputs through their dendritic trees in the inner plexiform layer (IPL) and transmitting the information via their axons in the retinal nerve fiber layer (RNFL) to the brain1,2,3,4. In diseased conditions such as glaucoma, early RGC degeneration may result in subtle changes in the RNFL, the ganglion cell layer (GCL), the IPL, and the optic nerve in both patients and rodent models5,6,7,8,9. Early detection of these morphological changes in RGCs is thus essential for timely intervention to prevent RGC and vision loss.
We have recently developed a new clinical-ready imaging technology called visible-light optical coherence tomography (vis-OCT) to satisfy the need for in vivo monitoring of RGC damage. Vis-OCT improved the axial resolution, reaching 1.3 &#181;m in the retina10, 11, allowing for the visualization of individual RGC axon bundles in the RNFL. Subsequently, vis-OCT fibergraphy (vis-OCTF) was established to track and quantify RGC damage at the single axon bundle level in mice11,12,13. However, ex vivo confocal imaging of the same retina as the gold standard is often necessary to validate the in vivo findings. Therefore, this study will demonstrate how to align in vivo images acquired by vis-OCTF with ex vivo confocal images of the same mouse retina. The protocol aims to validate the in vivo findings by ex vivo confocal imaging and establish a foundation for examining the molecular and cellular changes underlying RGC damage in diseased conditions.

Author Spotlight: Advancements in In Vivo and Ex Vivo Retinal Imaging for Improved Glaucoma Diagnosis and Treatment 

Alignment of Visible-Light Optical Coherence Tomography Fibergrams with Confocal Images of the Same Mouse Retina

We present a protocol for aligning in vivo VIS-OCT images with ex vivo immunostained retinal nerve fibers to validate our novel imaging technology. VIS-OCT enables visualization of retinal nerve fibers in vivo, and this process confirms the accuracy of our findings. Our protocol combines in vivo and ex vivo imaging to provide a real time visualization of retina structure and confirm findings.The process is applicable to mouse models of eye diseases, provided the anterior eye portion allows for optical imaging. This includes diabetic retinopathy and retinal ischemia models. These studies lay the foundation for establishing an objective evaluation of neuro damage in humans, which can significantly improve glaucoma diagnosis and treatment in the future.

Watch this Scientific Journal Video about In Vivo Visible Light Optical Coherence Tomography OCT Mouse Retinal Imaging at JoVE.com

In Vivo Visible Light Optical Coherence Tomography (OCT) Mouse Retinal Imaging  

Start by positioning the anesthetized mouse on the animal holder and securing it with two Velcro straps. Turn on the computer and open the software to activate the laser. Adjust the animal holder to center the laser in the mouse's eye.Visualize the posterior part through an on-face preview, the field of view of the superficial vascular plexus, a B scan, and the retina cross-section within the field of view. Acquire a visible light optical coherence tomography, or vis-OCT volume after making minor adjustments to the optical focus. Align the optical nerve head in each of the four corners of the field of view to cover different retinal areas.Use an intensity-based threshold method to detect the retina surface, and generate vis-OCT fiber grams from the volume. Crop the retinal nerve fiber layer, or RNFL, by selecting the first 16 micrometers depth. Next, calculate the mean intensity projection along the axial direction to generate the fiber gram image composed of retinal ganglion cell axon bundles and surrounding vasculature.Align the blood vessels using a graphics editor to montage the four images post-processing. The composite vis-OCT fiber gram is compared with the corresponding confocal image of flat-mounted retina immunostained with TUJ1 for RGC axons. Blood vessels exhibit distinguishable branching structures which can be matched with the ICAM II labeled blood vessels on the confocal image.Side-by-side comparison between ex vivo confocal microscopy and in vivo vis-OCT revealed identical RGC exon bundle networks and surrounding retinal vasculature.

Research

JoVE Journal

Neuroscience

In recent years, in vivo retinal imaging, which provides non-invasive, real-time, and longitudinal information about biological systems and processes, has ...