Optic Nerve Crush Model

The optic nerve crush model mimics severe damage to the optic nerve similar to that of traumatic optic neuropathy and optic nerve degeneration in glaucoma. Optic nerve crush leads to axonal degeneration and initiates apoptosis in retinal ganglion cells which over time causes vision loss. The purpose of this model is to test new and novel treatments that may help us to understand the mechanisms behind neuronal death and to treat types of optic neuropathy.

This is similar to ONC in rats although this is a more difficult approach with a higher likelihood of adverse effects or events from the procedure. However, the benefit of conducting this model in mice is that it allows for whole retina imaging for retinal flat mounts. Using mice for this model is more appealing in academic settings because it tends to be slightly cheaper and mice are easier to house.

The most relevant clinical sign of optic nerve damage is optic nerve cupping or enlargement of the cup-to-disc ratio. This is caused by a sustained increase in intraocular pressure causing a condition where the depression of the optic nerve in the posterior aspect of the eye to increase in size. If left unchecked apoptosis will initiate in the retinal ganglion cells and vision loss will progressively get worse. Both cup-to-disc ratio and thinning of the retina nerve fiber layer (RNFL) can be measured by OCT. Increases in cup-to-disc ratio and thinning of the RNFL are indications of glaucoma.

Optic neuritis is most commonly associated with autoimmune disorders with most cases being associated with multiple sclerosis (MS) but can also be caused by an infection.