word blindness

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a·lex·i·a

, optic alexiasensory alexiavisual alexiamotor alexia (ă-lek'sē-ă),
An inability to comprehend the meaning of written or printed words and sentences, caused by a cerebral lesion. Also called optic alexia, sensory alexia, visual alexia, to differentiate from motor alexia (anarthria), in which there is loss of the power to read aloud even though the significance of what is written or printed is understood.
[G. a- priv. + lexis, a word or phrase]

word blindness

n.
See alexia.

word′-blind′ adj.

word blindness

Etymology: AS, word + blind
an inability to understand written language. A form of receptive aphasia caused by lesions in the parietal or parietal-occipital areas of the brain. The condition may be congenital or acquired as a result of disease or injury. Also called alexia. Compare dyslexia.

blindness

(blind'nes)
Inability to see. The leading causes of blindness in the U.S. are age-related macular degeneration, diabetic retinopathy, and glaucoma.

Blindness may be caused by diseases of the lens, retina, or other eye structures; diseases of the optic nerve; or lesions of the visual cortex or pathways of the brain. A small number of infants are born blind, but far more people become blind during life. In the U.S., blindness due to infection is rare, but worldwide diseases like trachoma and onchocerciasis are relatively common causes of severe visual impairment. In malnourished people, vitamin A deficiency is an important cause of blindness.

A variety of free services are available for the blind and physically handicapped. Talking Books Topics, published bimonthly in large-print, cassette, and disc formats, is distributed free to the blind and physically handicapped who participate in the Library of Congress free reading program. It lists recorded books and magazines available through a national network of cooperating libraries and provides news of developments and activities in library services. Subscription requests may be sent to Talking Books Topics, CMLS, P.O. Box 9150, Melbourne, FL 32902-9150.

amnesic color blindness

Inability to remember the names of colors.
Enlarge picture
TEST FOR COLOR BLINDNESS

color blindness

A genetic or acquired abnormality of color perception. Complete color blindness, a rare disease, is called achromatopsia. Red-green color blindness, which affects about 8% of the male population, is an X-linked trait. Although color blindness is the term most commonly used, it is inaccurate:color deficiency and color vision deficiency are preferred. See: illustration

cortical blindness

Blindness due to lesions in the left and right occipital lobes of the brain. The eyes are still able to move, and the pupillary light reflexes remain, but the blindness is as if the optic nerves had been severed. The usual cause is occlusion of the posterior cerebral arteries. Transitory cortical blindness may follow head injury.
Synonym: cerebral visual impairment

day blindness

Hemeralopia.

eclipse blindness

Blindness due to burning the macula while viewing an eclipse without using protective lenses. Looking directly at the sun at any time can damage the eyes. Synonym: solar blindness; solar maculopathy

green blindness

Aglaucopsia.

hysterical blindness

An inaccurate term for functional blindness, i.e., blindness caused by psychological disorders rather than by demonstrable organic pathology.

legal blindness

A degree of loss of visual acuity that prevents a person from performing work requiring eyesight. In the U.S. this is defined as corrected visual acuity of 20/200 or less, or a visual field of 20° or less in the better eye. In the U.S. there are about three quarters of a million blind people, and about 8 or 9 million people with significant visual impairment.

letter blindness

A form of aphasia marked by an inability to understand the meaning of letters.

night blindness

Nyctalopia (1).

note blindness

The inability to recognize musical notes. It is due to a lesion of the central nervous system.

object blindness

A disorder in which the brain fails to recognize things even though the eyes function normally.
See: apraxia

psychic blindness

Sight without recognition due to a brain lesion.

red-green blindness

Red-green color blindness

red-green color blindness

Inability to see red hues. It is the most common kind of color blindness. Synonym: red-green blindness

river blindness

See: onchocerciasis

snow blindness

Blindness, usually temporary, due to the glare of sunlight on snow. It may result in photophobia and conjunctivitis, the latter resulting from effects of ultraviolet radiation.

solar blindness

Eclipse blindness.

taste blindness

An inability to taste certain substances such as phenylthiocarbamide. This inability is due to an autosomal recessive trait.

transient monocular blindness

A temporary loss of vision affecting one eye. In older adults it is usually a form of transient ischemic attack, caused by carotid atherosclerosis, and is therefore a harbinger of stroke. In young adults it may be caused by migraine. Synonym: amaurosis fugax

Etiology

In older adults, causes of carotid atherosclerosis include smoking, diabetes mellitus, hypertension, obesity, and hypercholesterolemia. When atherosclerotic plaques form within the carotid artery, they may ulcerate. The exposed endothelium within the artery becomes a focus of inflammation and blood clotting. Blindness occurs when tiny clots from the carotid arteries embolize to the ophthalmic arteries.

Symptoms

Patients often describe a dark shade descending into the field of vision. At the same time they may have other stroke symptoms, e.g., difficulty with speech or weakness of the hand on the side opposite the affected eye.

Treatment

A patient who may have carotid atherosclerosis should begin taking aspirin or other antiplatelet drugs if these are tolerated. Blood pressure and lipid levels should be controlled. The patient should be referred for noninvasive evaluation of blood flow through the carotid arteries, e.g., ultrasonography. If the carotid arteries are significantly blocked, the patient and physician should consider the risks and benefits of carotid endarterectomy.

violet blindness

Inability to see violet tints.

word blindness

Alexia.

word blindness

See DYSLEXIA.

dyslexia

or

word blindness

impairment of the ability to read, write and speak, due to a brain disorder. Dyslexia is characterized by a discrepancy between high ability in some areas and poor performance in others. There are often sequencing difficulties which affect short-term memory so that multi-syllabic words cannot always be repeated or recalled.

alexia 

Inability to recognize written or printed words due to a lesion in the brain. This is a form of visual agnosia. Syn. word blindness. See agnosia; dyslexia.