<em>In Vivo</em> Imaging of <em>Cx3cr1^gfp/gfp</em> Reporter Mice with Spectral-domain Optical Coherence Tomography and Scanning Laser Ophthalmoscopy

Abstract

Spectral domain optical coherence tomography (SD-OCT) and scanning laser ophthalmoscopy (SLO) are extensively used in experimental ophthalmology. In the present protocol, mice expressing green fluorescent protein (gfp) under the promoter of Cx3cr1 (BALB/c-Cx3cr1) were used to image microglia cells in vivo in the retina. Microglia are resident macrophages of the retina and have been implicated in several retinal diseases. This protocol provides a detailed approach for generation of retinal B-scans, with SD-OCT, and imaging of microglia cell distribution in Cx3cr1 mice with SLO in vivo, using an ophthalmic imaging platform system. The protocol can be used in several reporter mouse lines. However, there are some limitations to the protocol presented here. First, both SLO and SD-OCT, when used in the high-resolution mode, collect data with high axial resolution but the lateral resolution is lower (3.5 µm and 6 µm, respectively). Moreover, the focus and saturation level in SLO is highly dependent on parameter selection and correct alignment of the eye. Additionally, using devices designed for human patients in mice is challenging due to the higher total optical power of the mouse eye compared to the human eye; this can lead to lateral magnification inaccuracies, which are also dependent on the magnification by the mouse lens among others. However, despite that the axial scan position is dependent upon lateral magnification, the axial SD-OCT measurements are accurate.

Semi-Automated Live Tracking of Microglial Activation in CX3CR1GFP Mice During Experimental Autoimmune Encephalomyelitis by Confocal Scanning Laser Ophthalmoscopy

“…The retina represents an easily accessible compartment of the CNS for in vivo imaging by OCT as well as fundus imaging and live-cell tracking by cSLO ( 26 , 37 ). Longitudinally tracking the microglial cSLO outcomes revealed a steadily increasing CC and SuA of all experimental groups over the period of 12 weeks, although the sham-treated and naïve mice were not MOG 35-55 immunized.…”

Optimal Efficacy and Safety of Humanized Anti-Scg3 Antibody to Alleviate Oxygen-Induced Retinopathy

“…OCT was performed at P42 as previously described (Spectralis™ HRA + OCT device from Heidelberg Engineering, Franklin, MA, USA) [ 40 ]. Briefly, set the Automatic Real-Time (ART) value to at least 7 to obtain high-quality images.…”

Using Optical Coherence Tomography and Optokinetic Response As Structural and Functional Visual System Readouts in Mice and Rats

“…Many OCT devices allow simultaneous confocal scanning laser ophthalmoscopy (cSLO) imaging with different wavelengths, which provides diagnostic information about retinal pathologies, i.e., visualization of lipofuscin deposits or alterations of the retinal pigment epithelium 27 . Furthermore, in vivo imaging of fluorescence labelled cells in transgenic animals is possible 28,29,30,31,32 . However, the application of OCT technology in rodent models is still challenging, mainly because of the small eye size.…”