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Lesions involving the whole optic nerve cause complete blindness on the affected side, that means damage at the right optic nerve causes complete loss of vision in the right eye. [3] Optic neuritis involving external fibers of the optic nerve causes tunnel vision. [4] Optic neuritis involving internal fibers of the optic nerve causes central ...
The term "disc-at-risk" refers to an optic nerve head characterized by a small cup-to-disc ratio and a crowding of optic nerve fibers. This anatomical feature is a significant factor in the development of NAION. [4] [5] Individuals predisposed to this condition typically have smaller optic discs with minimal or no cupping. This anatomical ...
The optic nerve can be damaged when exposed to direct or indirect injury. Direct optic nerve injuries are caused by trauma to the head or orbit that crosses normal tissue planes and disrupts the anatomy and function of the optic nerve; e.g., a bullet or forceps that physically injures the optic nerve.
The optic nerve is the bundle of axons that carry the visual signals from the eye to the brain. This optic nerve must penetrate through the wall of the eye, and the hole to accommodate this is usually 20-30% larger than the nerve diameter. In some patients the optic nerve is nearly as large as the opening in the back of the eye, and the optic ...
Arteritic anterior ischemic optic neuropathy (arteritic AION, A-AION or AAION) is vision loss that occurs in giant cell arteritis (also known as temporal arteritis). Temporal arteritis is an inflammatory disease of medium-sized blood vessels that happens especially with advancing age.
The anterior optic nerve receives blood primarily from the posterior ciliary arteries. The anterior optic nerve, a.k.a. the optic nerve head, is surrounded by the scleral canal, and is vulnerable to crowding of nerve fibers. The portion of the optic nerve head that is visible by looking into the eye with an ophthalmoscope is called the optic disc.
Ischemic optic neuropathy (ION) is the loss of structure and function of a portion of the optic nerve due to obstruction of blood flow to the nerve (i.e. ischemia).Ischemic forms of optic neuropathy are typically classified as either anterior ischemic optic neuropathy or posterior ischemic optic neuropathy according to the part of the optic nerve that is affected.
The most common cause is multiple sclerosis (MS) or ischemic optic neuropathy due to thrombosis or embolism of the vessel that supplies the optic nerve. [ 13 ] [ 14 ] Up to 50% of patients with MS will develop an episode of optic neuritis, and 20–30% of the time optic neuritis is the presenting sign of MS .