Thursday, July 31, 2014

The Causes of Blindness

A recent analysis of data indicates that vitamin A deficiency is the leading cause of childhood blindness. It was estimated that 70% of the 500,000 children who become blind annually do so because of xerophthalmia. This corresponds to a prevalence of roughly 1 million in view of the high mortality among affected children.

Hemianopsia can result when a hemorrhagic, thrombotic, or embolic stroke affects part of the optic pathway Associated signs and symptoms vary according to the location and size of the stroke, but may include a decreased LOC; intellectual deficits, such as memory loss and poor judgment; personality changes; emotional lability; a headache; and seizures The patient may also develop contralateral hemiplegia, dysarthria, dysphagia, ataxia, a unilateral sensory loss, apraxia, agnosia, aphasia, blurred vision, decreased visual acuity, and diplopia

The link between poverty and treatable visual impairment is most obvious when conducting regional comparisons of cause. Most adult visual impairment in North America and Western Europe is related to age-related macular degeneration and diabetic retinopathy. While both of these conditions are subject to treatment, neither can be cured. Another common cause is retinopathy of prematurity. In developing countries, wherein people have shorter life expectancies, cataracts and water-borne parasites—both of which can be treated effectively—are most often the culprits (see River blindness, for example). Of the estimated 40 million blind people located around the world, 70–80% can have some or all of their sight restored through treatment.
Another disease is called Trachoma.

Trachoma is caused by a virus that affects the cornea and the conjunctiva or lining of the eyelid. The white part of the eye is called the sclera, and the colored part is the iris. The conjunctiva covers the sclera. Trachoma is contagious. It is spread by flies and contact with towels and other articles that have been used by people who have the disease. Physicians can cure the disease in the early stages by using medicines.

There are different causes of change blindness. According to scientists, change blindness can happen as a result of disturbance or disruption in visual continuity. This disruption can be either due to eye saccade, an eyelid flicker, an eye blink, a shift of the picture or even a film cut in case of a motion picture. In order to differentiate changes in the vision, it is important that there is effective coordination between the eye and the brain where one image is compared with another image that already exists in the memory.

Diseases: These are the leading cause of blindness. There are a variety of diseases that lead to blindness. Popular among these glaucoma, trachoma, cataracts, uveitis and diabetic retinopathy. While in some cases blindness occurs as a result of a parasitic infection in the eye, in others it occurs as a result of malnutrition. Blindness due to vitamin A deficiency is common in most of the developing and under-developed countries.

Glaucoma generally affects older people. This happens when fluids in the eye build up and cause too much pressure in the eye, damaging important nerves, etc.. To know what a person feels like with glaucoma, think of how your eyes feel after coming out of a swimming pool with a lot of chlorine in it. (This does not cause glaucoma, but makes the eyes feel as a person does with glaucoma)This disease can be prevented and eye doctors almost always check for glaucoma when a patient has an eye exam. If the person who has glaucoma doesn't take the appropriate medicine for the condition, they can lose their eyesight.
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