Optic neuritis

Optic neuritis is also defined as the inflammation of the optic nerve that may cause a complete or partial loss of vision. It is also known a the retro-bulbar neuritis. In this, there is also the demyelination of the optic nerve that is nerve that transmits light and visual images from the retina to the brain.

Causes of optic neuritis

This optic nerve comprises axons that emerge from the retina of the eye and carry visual information to the primary visual nuclei, most of the which is relayed to the occipital cortex of the brain to be processed into vision. Inflammation of the optic nerve causes loss of vision usually due to the swelling and destruction of the myelin sheath covering the optic nerve.

Direct axonal damage may also play a role in nerve destruction in may cases. Some causes are viral bacterial infection, for egr herpes zoster, autoimmune disorders, for egr lupus, and the inflammation of vessels known as vasculitis, nourishing the optic nerve. Optic neuritis can also emerge as attendant, first or sole manifestation of multiple sclerosis.

Symptoms of optic neuritis

Optic neuritis is generally experienced as an acute blurring, graying, loss of vision, most often in only one eye. It is rare that both eyes are affected at the same time. There may or may not be pain in the affected eye. Loss of vision usually reaches its maximum extent within a few days and generally improves within 4 to 12 weeks without treatment.

Occasionally there may be pain on movement of the eyes. Many patients with optic neuritis may lose their colour vision also. On medical examination the head of the optic nerve can easily be visualized by an ophthalmoscope.

In many cases, only one eye is affected and patients may not be aware of the loss of colour vision until the doctor asks them to close or cover the healthy eye. A person may have sub -clinical episode of optic neuritis. That is there may be inflammation and demyelination of the optic nerve that occurs without affecting visual function so that the person is not aware of any changes.