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Eye Information from NAVH
NAVH maintains comprehensive information about the eye, vision, and medical conditions related to the eye and vision.
What is the difference between Low Vision, Legal Blindness and Total Blindness?
Did you know that the visually impaired are the second largest group of disabled people in the United States?
Low Vision - If corrective lenses cannot provide 20/40 sight in at least one eye you have low vision. Those who have low vision may or may not be legally blind.
Legal Blindness - Those who are legally blind test 20/200 or less in the better eye after the best correction or have a field defect in which the widest diameter of the visual field is no greater that 20 degrees.
Total Blindness is the complete lack of vision either as a result of neurological or physiological factors. Those who do not have form or visual light perception are considered blind.
There is a lot of variation within the low vision and legally blind categories. Some individuals who fall into these categories can read without Braille while others cannot. Some do not need assistance walking or completing activities of daily living while others do. The bottom line is that these individuals have some vision and are not totally blind.
Consider that the leading cause of low vision and legal blindness is macular degeneration which, alone, will NEVER cause complete vision loss. Most cases of diabetic retinopathy do not produce total blindness, although the disease is the leading cause of profound vision loss among young working adults in the United States. Glaucoma, the second leading cause of vision loss in the world, does not lead to total blindness when successfully treated. Retinitis pigmentosa, in the majority of cases, allows for some residual vision.
Thus there is a tremendous need for services for those with low vision.
And why is that difference so important?
Those who are almost or totally blind are unable to benefit from the wide array of visual aids and thus require skills in the use of canes, guide dogs, as well as orientation and mobility training. The partially seeing, however, have needs which vary greatly with age, the degree of motivation, and type of impairment. Training the partially seeing to use residual vision is a far more expensive and complicated process.
If you have limited vision, that is, if you belong to the majority among those who have serious eye problems, you will find that information and services available to you are sparse. And what's worse, the world at large, perhaps including your family and friends, often do not understand your vision is limited and you have trouble seeing, although you are not blind. That is a difficult concept for many.
The ability to see is not just black and white. There are many shades of gray, and those with limited vision live in the gray area.
The modern age of computers has created new challenges for the "hard of seeing." The good news is that contemporary operating systems and web browsers provide excellent accessibility options. We encourage everyone to learn about these capabilities.
Learn More!
We invite you to explore our web site for more helpful information and to Contact Us directly if you have questions, need more information or would like to get involved.
Common Eye Diseases
The Eye & Your Vision is a booklet published by NAVH that describes common refractive errors such as near sightedness (myopia), far sightedness (hyperopia), astigmatism (an irregular shape of the normally spherical cornea surface), and presbyopia as well as brief descriptions about common diseases such as cataracts, macular degeneration, glaucoma, diabetic retinopathy and a section on visual aids. Please contact us in order to obtain a copy of this informative booklet.
Many people think Cataracts are some sort of growth over the surface of the eye. We set the record straight with this article.
Macular Degeneration is an age-related condition affecting the eye. There are several types and it is a complex problem, resulting in varying outcomes.
Glaucoma is the second leading cause of blindness in the United States, the leading cause of blindness among African-Americans, and the leading cause of PREVENTABLE blindness in the U.S.
Diabetes is the leading cause of new cases of legal blindness in the United States among working-age adults. This article is an attempt to help you understand the connection between diabetes and Diabetic Retinopathy.
Did you know that the visually impaired are the second largest group of disabled people in the United States? Read more about the Psychological Effects of Low Vision in an article authored by our founder.