Ischemic optic neuropathy (ION) is the loss of structure and function of a portion of the

optic nerve In neuroanatomy, the optic nerve, also known as the second cranial nerve, cranial nerve II, or simply CN II, is a paired cranial nerve that transmits visual system, visual information from the retina to the brain. In humans, the optic nerve i ...

due to obstruction of blood flow to the nerve (i.e.

ischemia Ischemia or ischaemia is a restriction in blood supply to any tissue, muscle group, or organ of the body, causing a shortage of oxygen that is needed for cellular metabolism (to keep tissue alive). Ischemia is generally caused by problems wi ...

). Ischemic forms of

optic neuropathy Optic neuropathy is damage to the optic nerve from any cause. The optic nerve is a bundle of millions of fibers in the retina that sends visual signals to the brain. Damage and death of these nerve cells, or neurons, leads to characteristic featu ...

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. People affected will often complain of a loss of

visual acuity Visual acuity (VA) commonly refers to the clarity of vision, but technically rates an examinee's ability to recognize small details with precision. Visual acuity is dependent on optical and neural factors, i.e. (1) the sharpness of the retinal ...

and a

visual field The visual field is the "spatial array of visual sensations available to observation in introspectionist psychological experiments". Or simply, visual field can be defined as the entire area that can be seen when an eye is fixed straight at a point ...

, the latter of which is usually in the superior or inferior field. When ION occurs in patients below the age of 50 years old, other causes should be considered, such as juvenile diabetes mellitus,

antiphospholipid antibody Antiphospholipid syndrome, or antiphospholipid antibody syndrome (APS or APLS), is an autoimmune, hypercoagulable state caused by antiphospholipid antibodies. APS provokes blood clots (thrombosis) in both arteries and veins as well as pregnancy-re ...

-associated

clotting disorders Coagulopathy (also called a bleeding disorder) is a condition in which the blood's ability to coagulate (form clots) is impaired. This condition can cause a tendency toward prolonged or excessive bleeding (bleeding diathesis), which may occur spo ...

, collagen-vascular disease, and

migraines Migraine (, ) is a common neurological disorder characterized by recurrent headaches. Typically, the associated headache affects one side of the head, is pulsating in nature, may be moderate to severe in intensity, and could last from a few hou ...

. Rarely, complications of

intraocular surgery Eye surgery, also known as ophthalmic or ocular surgery, is surgery performed on the human eye, eye or its Accessory visual structures, adnexa, by an ophthalmologist or sometimes, an optometrist. Eye surgery is synonymous with ophthalmology. The ...

or acute

blood loss Bleeding, hemorrhage, haemorrhage or blood loss, is blood escaping from the circulatory system from damaged blood vessels. Bleeding can occur internally, or externally either through a natural opening such as the mouth, nose, ear, urethra, vag ...

may cause an ischemic event in the optic nerve.

Presentation

Anterior ION presents with sudden, painless

visual loss Visual impairment, also known as vision impairment, is a medical definition primarily measured based on an individual's better eye visual acuity; in the absence of treatment such as correctable eyewear, assistive devices, and medical treatment� ...

, developing over hours to days.

Diagnosis

Examination findings usually include decreased visual acuity, a visual field defect,

color vision Color vision, a feature of visual perception, is an ability to perceive differences between light composed of different wavelengths (i.e., different spectral power distributions) independently of light intensity. Color perception is a part of ...

loss, a

relative afferent pupillary defect A relative afferent pupillary defect (RAPD), also known as a Marcus Gunn pupil, is a medical sign observed during the swinging-flashlight test whereupon the patient's pupils dilate when a bright light is swung from the unaffected eye to the affec ...

, and a swollen

optic nerve head The optic disc or optic nerve head is the point of exit for ganglion cell axons leaving the eye. Because there are no rods or cones overlying the optic disc, it corresponds to a small blind spot in each eye. The ganglion cell axons form the ...

. Posterior ION occurs arteritic, nonarteritic, and surgical settings. It is characterized by acute vision loss without initial disc

edema Edema, also spelled oedema, and also known as fluid retention, dropsy, hydropsy and swelling, is the build-up of fluid in the body's Tissue (biology), tissue. Most commonly, the legs or arms are affected. Symptoms may include skin which feels t ...

, but with subsequent optic disc atrophy."Chapter 7: Ischemic Optic Neuropathy." Walsh and Hoyt's Clinical Neuro-ophthalmology. Ed. Neil R. Miller, Frank Burton Walsh, and William Fletcher Hoyt. Illustrated ed. Vol. 1. N.p.: Lippincott Williams & Wilkins, 2005. N. pag. Print.

Management

Although there is no recognized treatment that can reverse the visual loss, upon recent reports, optic nerve health decompression may be beneficial for a select group of patients with a gradual decline in vision due to ION.Oria, Veronica. "Ischemic Optic Neuropathy: Abstract." Seminars in Neurology. By Monica Rodriguez Fontal, John B. Kerrison, and Reinaldo Garcia. N.p.: Thieme, 2007. N. pag. Print.

References

* ''Dictionary of Eye Terminology'', Triad Publishing Company, 1990. Disorders of optic nerve and visual pathways {{nervoussystem-disease-stub

Presentation

Diagnosis

Management

See also

References