Causes of optic neuritis
Optic neuritis is a kind of eye disease, which is the inflammation of the optic nerve. The optic nerve begins from the retinal ganglion cell axons, and leaves the orbit via the optic canal to the optic chiasm, and terminates in the lateral geniculate nucleus. Optic neuritis can divided into two kinds, inflammation of the optic disc and retrobulbar optic neuritis according to the part of the optic nerve that was infected.
Optic neuritis typically affects people ranging from 18-45 years of age. Females are much easier to be affected with optic neuritis, and it is twice as often as men. Bilateral optic neuritis in childhood is not uncommon, and there is less risk of progression to multiple sclerosis.
The most common symptoms of optic neuritis are sudden loss of vision, or a sudden blurred vision, and the patient may suffer pain on movement of the affected eye. In most cases, visual functions can return to normal or near normal within two to three months, but they may also advance to a complete and permanent state of visual loss.
The causes of optic neuritis are complex. The most common etiology for the inflammation of the optic nerve that causes vision loss is the swelling and destruction of the myelin sheath covering the optic nerve. Direct axonal damage may also cause nerve destruction in many cases. Some other causes involving viral-bacterial infections, autoimmune disorders, chloramphenicol and the inflammation of vessels nourishing. Antitubercular drugs, such as ethambutol, can also cause optic neuritis.
Optic neuritis can be diagnosed via eye examination, the head of the optic nerve can easily be visualised by an ophthalmoscope. And magnetic resonance imaging (MRI) is a highly sensitive and specific tool in assessing inflammatory changes in the optic nerves and helps to rule out structural lesions.