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Eye Anatomy
Number of Americans with Vision Loss
Employment
Getting Around
Special Education
Computer Use
National Resources
State Resources

Eye Anatomy
The eye is a complex organ composed of many parts. Good vision depends on the way in which those parts work together. It is helpful to understand how the eye works before learning about macular degeneration and other forms of low vision.

The eye is a spherical structure about an inch in diameter. It has a clear bulge on the front side, which is the cornea. The wall of the eye beyond the cornea consists of three tissue layers. The outermost layer is the sclera, a tough, protective coating that covers most of the outer surface of the eye that connects to the transparent cornea at the front of the eye. The middle layer is the choroid, a vascular layer that is continuous with the ciliary body and the iris on the front side of the eye. The inner layer is the retina, a light-sensitive tissue that lines the inside back wall of the eye. To understand how the eye works, it is useful to think of a camera. The human eye is more complex than a television camera, but the principles are similar.

Vision begins when light rays are reflected off an object and enter the eyes through the cornea, the transparent outer covering of the eye. The cornea bends or refracts the rays that pass through a round hole called the pupil. The iris, or colored portion of the eye that surrounds the pupil, opens and closes (making the pupil bigger or smaller) to regulate the amount of light passing through. The light rays then pass through the lens, which actually changes shape so it can further bend the rays and focus them on the retina at the back of the eye. The retina is a thin layer of tissue at the back of the eye that contains millions of tiny light-sensing nerve cells called rods and cones, which are named for their distinct shapes. Cones are concentrated in the center of the retina, in an area called the macula. In bright light conditions, cones provide clear, sharp central vision and detect colors and fine details. Rods are located outside the macula and extend all the way to the outer edge of the retina. They provide peripheral or side vision. Rods also allow the eyes to detect motion and help us see in dim light and at night. These cells in the retina convert the light into electrical impulses. The optic nerve sends these impulses to the brain where an image is produced.


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Number of Americans with Vision Loss
More than 20 million Americans report experiencing significant low vision.

The exact figure from the National Health Interview Survey was 21.2 million Americans who reported experiencing vision loss.

Definition and scope: The term vision loss refers to individuals who reported that they have trouble seeing, even when wearing glasses or contact lenses, as well as to individuals who reported that they are blind or unable to see at all. This estimate pertains to a nationally representative sample of the noninstitutionalized civilian population 18 years of age and over.

How many older Americans have vision loss?

There are approximately 6.2 million seniors (65 years of age and over) that are visually impaired. There are approximately 9 million Americans 45 to 64 years of age who are visually impaired. As the 9 million baby boomers with vision loss continue to age, the number of seniors who have impaired vision will continue to grow substantially.

Furthermore, the NHIS estimates pertain to the noninstitutionalized civilian population. Seniors in nursing homes, for example, are not included in these data. Thus, there is reason to believe that the rate of vision loss among seniors is substantially greater than indicated by the NHIS.

Definition and scope: The term low vision refers to individuals who reported that they have trouble seeing, even when wearing glasses or contact lenses, as well as to individuals who reported that they are blind or unable to see at all. As mentioned, this estimate pertains to a nationally representative sample of the noninstitutionalized civilian population.

Data source: National Center for Health Statistics, National Health Interview Survey, www.cdc.gov/nchs/nhis.htm. For further information, see "Pleis J.R., Lethbridge-Çejku M. Summary health statistics for U.S. adults: National Health Interview Survey. National Center for Health Statistics. Vital Health Stat 10 (235).

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Employment
Several recommended resources for employment statistics are provided in Featured Resources for Employment Statistics.

Investigators are advised that there are no perfect employment statistics currently available pertaining to Americans who are visually impaired. A primary limitation of the currently available nationally-representative data sources is that people who have impaired vision are often grouped together with all people who have sensory impairments. In other instances, people with vision loss are grouped together with all people who have a disability in communication. Consequently, Americans with vision loss cannot be separated from Americans who have other sensory impairments such has hearing loss, for example.

Employment statistics pertaining to people with vision loss differ based on the scope and definitions of vision loss used, as well as on the dates the data were collected, populations surveyed, survey methodology, and other features of data sources. Please pay attention to information provided about the data source. The background information is necessary for the accurate interpretation and use of these data.

Educational Attainment

How much schooling have Americans with low vision received?Of Americans who have vision loss and are 25 years of age and over, 4.5 million have less than a high school diploma, 6.0 million have a high school diploma or a GED, 5.4 million have some college education, and 3.6 million have a bachelor's degree or higher.

Definition and scope: The term visually impaired refers to individuals who reported that they have trouble seeing, even when wearing glasses or contact lenses, as well as to individuals who reported that they are blind or unable to see at all. This estimate pertains to a nationally representative sample of the noninstitutionalized civilian population 25 years of age and over.
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Getting Around

Please note that this older estimate is provided pending the availability of more current information. In 1990, approximately 109,000 people who had a visually impairment in the U.S. used long canes to get around.

Definition and scope: The term low vision refers to individuals who have trouble seeing, even when wearing glasses or contact lenses, as well as to individuals who are blind or unable to see at all. This estimate pertains to noninstutionalized individuals.

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Special Education

Please note that this older estimate is provided pending the availability of more current information. It was estimated that in 1998 approximately 93,600 visually impaired or blind students, 10,800 of whom were deaf-blind, were being served in the special education program.

Definition and scope: This estimate pertains to students who were reported as being served in the special education system as blind, visually impaired, or deaf-blind. These students were 0-21 years of age. Legal blindness is a level of vision loss that has been defined by law to determine eligibility for benefits. It refers to explicitly to those who have a central visual acuity of 20/200 or less in the better eye with the best possible correction, or a visual field of 20 degrees or less. This estimate includes legally blind students and deaf-blind students as well as those commonly referred to as visually impaired. These visually impaired students have a vision loss with a visual acuity better than 20/200, and a visual field of better than 20 degrees.

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Computer Use

Please note that this older estimate is provided pending the availability of more current information. At least 1.5 million Americans who are visually impaired use computers.

The term vision loss includes people with any degree of limitation in seeing. Thus, these individuals with vision loss were further identified as having any limitation in seeing, a limitation in seeing, and a severe limitation in seeing. Applying these more specific measures of vision loss more a more detailed estimate is available. The total number of people ages 15 and older with any "limitation in seeing", who report they have access to the Internet is just over 1.5 million (1,549,000). The number of people ages 15 and older, with a limitation in seeing, who use a computer regularly is a bit under 1 million (979,000). Of those, about 196,000 people with a "severe" limitation in seeing have access to the Internet, and about 102,000 persons with a severe limitation in seeing use a computer on a regular basis.

Definition and scope: The term low vision refers to individuals who have trouble seeing, even when wearing glasses or contact lenses, as well as to individuals who are blind or unable to see at all. The term visually impaired includes people with any degree of limitation in seeing.

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