Optic Nerve Atrophy

Optic nerve & nervous system Types Symptoms Causes About the nervous system Treatment

Optic nerve atrophy, also known as optic neuropathy, simply defined, is the end result of any disease that damages nerve cells anywhere between the retina and a part of the thalamus that links the eye to the brain. Optic nerve atrophy is the condition wherein the optic nerve is limited in its capacity to transmit information accurately. While there are different causes associated with this disorder, the end result is the same, which is a degeneration, or "wasting away," of the nerve. Onset can occur from birth through adulthood.

When the ophthalmologist looks in your eye she can see that the pale optic nerve is visibly atrophied and looks pale. It has partially or seriously wasted away resulting in partial or serious loss or change in vision.

Next: Nutritional support, diet, & lifestyle tips for the optic nerve.

The Nervous System

Everything we do consciously or unconsciously is intimately connected to the central nervous system (CNS), the central organizing power of the body. It is comprised of nerve cells in the brain and spinal cord. It receives, analyzes, and organizes all information coming from the five senses in every part of the body. It integrates the behind-the-scenes information communicated from organs of the body, glands, and every other entity that acts or reacts to physical, chemical, mental, and electrical stimuli.

The peripheral nervous system is comprised of the nerve cells that are not part of the brain or spinal cord and connects the CNS to the organs, glands, and extremities of the body.

The optic nerve is not part of the brain but it and the retina are considered to be part of the central nervous system. Like brain cells, the optic nerve begins to develop during the earliest embryonic stages. The cells of the optic nerve are covered with protective myelin.

The Optic Nerve

The optic nerve is responsible for carrying electrical impulses from the retina to our brain. Impulses that contain the information about what we see. The optic nerve is made up of ganglion nerve cells in the retina and glial cells.

Retinal ganglion cells receive information from the photoreceptors, and they transmit that information to different parts of the brain in the thalamus, hypothalamus, and midbrain.
Glial cells are not nerve cells, but they are essential to optic nerve health because they protect and insulate the optic nerve and supply it with nutrients.

optic nerve atrophy

In optic nerve atrophy nerve fibers atrophy and are lost, the protective myelin sheath around them shrinks, gliosis occurs and the optic cup (where the optic nerve enters the retina) widens. Gliosis means that glia cells proliferate or enlarge, crowding the nerve cells.

Types of Optic Neuropathy

In practice, optic neuropathy is not considered a disease, but rather a sign or symptom of potentially many disease processes. It is closely associated to a group of conditions, some of which are genetically based, while others are due to lifestyle considerations, such as chronic systemic inflammation, trauma, toxins, poor blood flow, and/or a lack of essential nutrients getting to the optic nerve. Thus, the prevalence of optic nerve atrophy depends on the prevalence of an underlying cause.

Ischemic optic neuropathy is caused by insufficient blood flow with an occlusion in blood supply vessels. It occurs in adults and is described as a “stroke” of the optic nerve. One type, arteritic anterior ischemic optic neuropathy, is an ophthalmic emergency. The other non-arteritic type involves swelling, which typically lessens over time, but vision does not improve.

Optic neuritis is caused by an inflamed optic nerve. In compressive optic neuropathy, lesions cause the optic nerve to become compressed. A similar condition in appearance is glaucomatous optic neuropathy.

Infiltrative optic neuropathy occurs when the tumors or an inflammatory process invades the nerve or the space around it. Traumatic optic neuropathy develops after direct or indirect injury to the eye or sometimes to the back of the head.

Mitochondria optic neuropathy involves failure in mitochondria functioning.

Nutritional optic neuropathy occurs when nutritional deficiencies cause severe problems.

Toxic optic neuropathy arises due to damage from various poisons, toxins, and some drugs.

Hereditary optic neuropathy is caused by genetic mutations, including Leber’s hereditary optic neuropathy.

Optic nerve atrophy type 1 appears in childhood, or during puberty, with visual loss that progresses during puberty until adulthood. The subsequent progression is chronic and very slow. This is a complete and permanent breakdown of optic nerve fibers.

Symptoms

The symptoms described here may not necessarily mean that you have optic nerve atrophy. However, if you experience one or more of these symptoms, contact your eye doctor for a complete exam.

Blurred vision
Decrease in visual function such as a decrease in sharpness and clarity of vision (visual acuity) or decreases in side (peripheral) vision. Color vision and contrast sensitivity can also be affected.
Poor constriction of the pupil in light
Decreased brightness in one eye relative to the other
Change in the optic disc which your doctor would see in an exam

Causes

Most commonly, optic nerve atrophy occurs without a known or proven cause.

Causes leading to optic atrophy range from eye injury or trauma to systemic eye conditions and diseases. These include:

Optic neuritis occurs when the optic nerve is inflammed due to autoimmune conditions, viral, fungal and bacterial infections, parasitic diseases, toxins, allergies, digestive problems, diabetes, and/or simply poor circulation. The person might notice eye pain which is more severe when they move their eye. It mostly found in young to middle-aged women. Such inflammation attacks the myelin covering and the optic nerve becomes swollen and, over time, damaged. Some people with this condition may develop multiple sclerosis later on in life.
Leber's hereditary optic neuropathy is a hereditary eye disease mostly occurring in late teens to early 20s young men. It is characterized by development over a few weeks of painless, serious, central visual loss in one eye, followed months or weeks later by the same process in the other eye. In the beginning there might be slight swelling, but eventually the optic nerve atrophied resulting in, usually, permanent vision loss.
Untreated glaucoma. Untreated, the increased pressure characteristic of glaucoma may eventually affect the optic nerve. Glaucoma is characterized by optic nerve atrophy.
Toxic optic neuropathy. Optic atrophy can result from nutritional deficiencies, some medications, and toxins which damage the optic nerve causing gradual or sudden vision loss. The most common optic neuropathy from poisons and toxins is called as tobacco-alcohol amblyopia, thought to be caused by exposure to cyanide from tobacco smoking, and by low vitamin B12. Other toxins include methyl alcohol (moonshine), ethylene glycol (antifreeze), cyanide, lead, and carbon monoxide.
Certain drugs are optic nerve toxins, including ethambutol, topiramate (Topamax) that can cause narrow angle glaucoma, and amiodarone that can cause blurred vision and ischemic optic neuropathy. Ethambutol is considered an optic nerve toxin.
Nutritional optic neuropathy may be caused by deficiencies in protein, B vitamins, vitamin B12, in particular, and folic acid which result from poor nutrition, starvation, poor absorption or alcoholism. Vitamin B12 deficiency damages the nerves, and drinking alcohol contributes to poor absorption of vitamin B12. Treatment with intramuscular B12 as well as oral B12 supplementation has been found to result in dramatic improvement in vision.¹
Compressive optic neuropathy results from a tumor or other lesion pressing on the optic nerve or from eye movement muscle enlargement which is seen in hyperthyroidism (Graves' disease) patients.
Syphilis, untreated, can also result in damage to the optic nerve.
Brain tumor or stroke may cause optic nerve atrophy.