This article describes a method for imaging the retina of a genetically modified mouse with optic atrophy using spectral-domain optical coherence tomography (SD-OCT). The procedure includes anesthetizing the mouse, preparing the eyes for imaging, and analyzing the resulting OCT images to assess retinal structure.
Take an anesthetized genetically modified mouse exhibiting optic atrophy.
The pupils are dilated for enhanced light penetration.
Administer anesthetic to immobilize the eyes. Apply drops for corneal hydration. Then, wrap the mouse in gauze to maintain body warmth.
Apply gel to minimize light refraction. Secure the mouse in the spectral-domain optical coherence tomography system cassette, ensuring proper head positioning.
Align the optical axes of the right eye and the imaging lens. Use alignment controls to center the optic nerve head in the imaging field, ensuring proper retinal alignment.
Low-coherence light directed into the retina reflects off layers with varying refractive indices. The reflected light combines with a reference beam to generate interference patterns, creating a high-resolution cross-sectional image of the retina.
After imaging, allow the mouse to recover.
The OCT image analysis reveals the thickening of the ganglion cell complex layer, a hallmark of optic atrophy.
Remove the drops and repeat the 10% phenylephrine and 0.5% tropicamide installation. When the eyes are sufficiently dilated for the imaging, lubricate the eyes with viscous glycol-based eyedrops to provide corneal hydration, and wrap the mouse in a sheet of surgical gauze to keep it warm.
Using a sponge or cotton wick, apply a thin layer of ophthalmic gel supplemented with 0.3% hypromellose onto each eye. While doing so, set the eyelashes and whiskers aside. Position the mouse in the cassette with the head straight and pointing forward, and carefully place the bite bar in its mouth. Place a cotton roll under the side of the animal for the eye that is being examined.
Then keeping the clip-on aiming tip on the mouse-specific lens, rotate the Z-translator screw counterclockwise to bring the lens towards the eye. Pre-set the position of the mouse by rotating and swiveling the cassette and turning the bite bar and the X-translator screws until the experimental eye is positioned to look directly into the lens.
When the optical axes of the eyes and the lens are aligned, select the first scan in the exam. Click Start Aiming, and use the Z-translator screw to move the retina vertically in the left panel and horizontally in the right panel. By rotating the cassette, move the optic nerve head up or down to bring it into the middle of the right panel. Use the bite bar screw to straighten the retina within the right panel and swivel the cassette to position the optic nerve head in the middle of the left panel.
Then, use the X-translator screw to level the retina within the left panel, and keeping in mind the major function of each modulator, further adjust the position of the retina for the perfect centralization on the optic nerve head. When the retina is in position, click Start Snapshot to begin the spectral domain optical coherence tomography scanning.
Do not forget to save the scan and the report. Adjust the centralization if necessary. Remove the mouse from the cassette. Apply ophthalmic gel with 0.3% hypromellose to each eye, and place the mouse on a heating plate with monitoring until full recovery.
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