Optic nerve transmits visual information from the retina to the brain. Also known as cranial nerve, the optic nerve connects the eyes to the brain. It carries impulses formed in the retina to the brain which interprets these impulses as images.
Optic neuritis is inflammation of the optic nerve(s) which results in interference with normal function of the eye by preventing retinal information from reaching the brain. In this condition, one or both optic nerves are swollen, resulting in impaired visual function. Optic neuritis affects nervous and ophthalmic systems of the body.
The secondary form of optic neuritis, in which the condition is secondary to another condition, such as central nervous system (CNS) dysfunction, is more common in dogs while the primary form of optic neuritis is uncommon and only affects dogs younger than three years of age.
The optic nerve may be inflamed along its entire length from the retina to the brain, or only a portion of the nerve may be affected. When the beginning of the nerve is inflamed, this inflammation is visible by examining the retina. When the nerve behind the eye is inflamed, the retina may appear normal.
Common symptoms associated with optic neuritis are sudden blindness or partial vision loss, pupils are completely fixed, dilated and unresponsive to light stimuli with a complete absence of vision reflex. An examination of the anterior surface of the eye cavity may reveal a swollen optic disk, or a focal hemorrhage.
