A Highly Reproducible and Straightforward Method to Perform In Vivo Ocular Enucleation in the Mouse after Eye Opening
October 6th, 2014
The removal of eyes, also called enucleation, provides a useful strategy to study aspects of visual, cross-modal, and developmental plasticity along the mammalian visual system since it induces irreversible partial (monocular) or complete (binocular) vision loss. Here we describe a highly reproducible and straightforward approach to perform in vivo enucleation.
The overall goal of this procedure is to successfully remove an eye from an anesthetized mouse in a very straightforward and reproducible manner. This is accomplished by first displacing the eyeball by gently pressing onto the canthus with a curved forceps. The second step of the procedure is to guide the forceps behind the eye, to firmly grasp the optic nerve.
The third step is to make circular movements. With the hand holding the forceps, the mouse body will move in the same direction. The final step is to gradually increase the speed of the movements to ensure constriction of the optic nerve resulting in the detachment of the eyeball.
Ultimately, the eye can be used to study the AFR visual pathway longitudinally by, for instance, revealing different sensory deprivation plasticity processes in the brain of the mouse. The main advantage of this technique over existing methods, which often use suturing and blunt dissection, is that our iation method is simply based on the constriction of the optic nerve, which results in minimal to no bleeding and is very easy to learn. Begin with anesthetizing the mouse using an intraperitoneal injection of a mixture of ketamine and meine in saline.
Confirm the sedation by checking the mouse's reflexes. Pinch the toes with forceps and check for a reflex response. If there is no response, then use a cotton tipped applicator and 70%ethanol to clean the eyelids and area around the eye.
If there is no eye blink response, proceed with the eye in nucleation. Put the mouse on a stable, flat, smooth, and dry surface. Sterilize the tips of the curved serrated forceps in a glass bead sterilizer.
The best tip size to use is 0.5 by 0.4 millimeters. Next, gently press onto the canthus with the forceps until the eyeball is displaced from the socket and the optic nerve is reachable. Then guide the forceps behind the eye and firmly press and hold the optic nerve with the optic nerve gripped Slowly begin moving the forceps in circles in the direction of least resistance.
Keeping the mouse against the operating table, the mouse should be secured. Its body should move as well. Gradually speed up until after seven to 15 circular movements, the optic nerve constricts and the eyeball detaches.
If the rotations are too quick or the forceps are pulled too hard, the nerve will break prematurely and pleading will follow. Begin with reversing the anesthesia. Give the mouse an intraperitoneal injection of aamaz all hydrochloride in saline.
Then intramuscularly administer 0.05. Milliliters of prepared pain reliever such as meloxicam and analgesia should be administered every 24 hours. Now, apply eye ointment to the remaining eye to prevent dehydration of the cornea.
Had this been applied before the surgery, it would've smeared onto the table. Move the mouse to a holding cage, control the mouse's body temperature using a heating plate or a blanket while it recovers when the animal regains motor control transfer it back to its home cage. A successful removal of the eye is characterized by the absence of bleeding or any apparent physical damage to the orbital tissue or eye socket.
The enucleated eye should have features of an intact globe like a smooth cornea and choroid. The optic nerve should be constricted at the base of the retina. The remaining length of nerve on the animal should show a clean cut and the surrounding brain area should not be damaged.
An experiment was conducted using these techniques followed by detection of Z 2 68 mRNA by radioactive in C two hybridization to uncover visually induced neuronal activity in the cerebral cortex. In contrast to visually stimulated controls, mice with both eyes and nucleated showed basal activity in the left and right visual cortex due to complete lack of visual input. As such, the borders between visual with non-visual cortex were uncovered.
Monocular enucleation revealed the two monocular driven regions as being hypoactive in the visual cortex contralateral to the remove dye. These regions are located medially and laterally to the central binocular zone. Once mastered, this technique can be done in less than one minute if performed properly.
Therefore, it provides an efficient method to examine activity, plasticity, or other phenomena in the ENT visual pathway.
Overview
This article presents a straightforward method for performing in vivo enucleation in mice, allowing researchers to study visual and cross-modal plasticity. The technique minimizes bleeding and is easy to learn, making it suitable for various experimental applications.
Key Study Components
Area of Science
- Neuroscience
- Visual System
- Plasticity Research
Background
- Enucleation induces vision loss, facilitating studies on visual processing.
- The procedure allows for the examination of sensory deprivation effects on the brain.
- Existing methods often involve complex techniques that can lead to complications.
- This method aims to provide a safer and more efficient alternative.
Purpose of Study
- To describe a reproducible technique for eye removal in mice.
- To enable the study of visual pathways and plasticity in the brain.
- To improve upon existing enucleation methods.
Methods Used
- Anesthetization of the mouse using a ketamine and saline mixture.
- Displacement of the eyeball using curved forceps.
- Grasping and constricting the optic nerve to detach the eyeball.
- Post-operative care including pain relief and monitoring recovery.
Main Results
- The technique resulted in minimal bleeding and intact surrounding tissues.
- Enucleated mice showed altered neuronal activity in the visual cortex.
- Monocular enucleation revealed hypoactivity in specific visual regions.
- The procedure can be performed efficiently in under one minute.
Conclusions
- The described enucleation method is effective for studying visual plasticity.
- It provides a reliable approach for investigating sensory deprivation effects.
- Future studies can leverage this technique for deeper insights into visual processing.
