Exact Number Of Blind Individuals example essay topic

The term blindness implies total or partial loss of vision involving both eyes. The exact level of vision defined as blindness, however, varies in different countries because of differing legal or social requirements. In the United States, blindness is defined as un improvable vision of 20/200 (6/60) or worse. This means that an individual is generally considered blind who, even with the use of ordinary eyeglasses, can see no better at 20 ft (6 m) than a person with normal vision can see at 200 ft (60 m).

On the other hand, the World Health Organization (WHO) Program Advisory Group on the Prevention of Blindness lists the vision level suggested as blindness as a visual acuity of less than 10/200 (3/60), which is twice as low as the U.S. definition. The WHOle vel of visual acuity is also described as the inability to count fingers in daylight at a distance of 10 ft (3 m), because in many regions a great number of people cannot receive formal eye examinations but may be tested by unspecialized personnel. From data available in the mid-1980's, the number of persons worldwide who have a visual acuity of less than 10/200 is estimated as 28 million. This level of handicap precludes an individual from functioning effectively in the community without special assistance and rehabilitation (see BLIND, EDUCATION OFTHE). Were the definition of blindness instead taken as 20/200, as is done in a number of industrialized countries besides the United States, the total number of blind persons in the world would be about 42 million.

The prevalence and causes of blindness vary according to the geographical location and economic status of a region. Thus in developing countries in tropical areas, the number of blind persons may reach at least 21 million (using the WHO definition). This high figure is due to the massive prevalence of such eye diseases as TRACHOMA, (RIVER BLINDNESS), and the NUTRITION-DEFICIENCY DISEASESkeratomalacia and xerophthalmia. In addition, few eye doctors are present in such regions to treat CATARACT or accidental eye injuries.

In other developing countries where eye care is not easily available and the presence of untreated cataract and undetected GLAUCOMA is also critical, the number of blind persons may reach 5.5 million. In developed countries with advanced medical services, on the other hand, most curable blindness is treated. Thus although many persons may have vision problems, the exact number of blind individuals may be less than 2 million. The main causes of blindness in such countries are age-related cataract, glaucoma, DIABETES, and macular degeneration (see EYE DISEASES). Inthe United States about 1 million cataracts are removed each year and vision improved with either an intraocular plastic lens, a contact corneal lens, or a cataract glass. Several million Americans are also being treated for glaucoma, which if caught in its early stages can usually be dealt with by medication or surgery.

PAUL HENKIND, M.D.

Bibliography

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Henkind, Paul, Priest, R.S., and Schiller, G., Compendium of Ophthalmology (1983);
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Koestler, Frances, The Unseen Minority: A Social History of Blindness in the United States (1976);
Lewis, Vicky, Development and Handicap, 3d ed. (1987);
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Sommer, Alfred, Nutritional Blindness (1982);
Warren, David, Blindness and Early Development (1977);
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