The Legally Blind: Meaning, Eligibility, Reasons, Treatment

'Legally blind' is a definition of blindness used by the United States Social Security Administration (SSA) to determine if someone is eligible for disability benefits, tax benefits, and education for the visually impaired .

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These terms can also be used by health insurers to define benefits and as part of vision exams required by the State Departments of Motor Vehicles (DMV) to determine eligibility for a driver's license. For safety reasons, people with legal blindness or low vision are generally not eligible for a driver's license.

According to the American Foundation for the Blind, "legally blind" is not the same as "completely blind," which is used to describe the inability to see anything with either eye. Most blind people have vision .


To be considered legally blind, you must meet one of two criteria: visual acuity (visual acuity) and visual field (the total amount of what you can see without moving your eyes).

Legal blindness criteria

You meet one of the following criteria :

  • Visual acuity of 20/200 or less in the eye that can see better (with corrective glasses or contact lenses)
  • Field of view no more than 20 degrees

Visual acuity

Visual acuity refers to how close a person must be to an object 20 feet away in order to see it in full detail. Normal vision is measured as 20/20. If you had a visual acuity of 20/80, that would mean that you could see detail at 20 feet in the same way that a person with 20/20, or normal vision, could see at 80 feet.

A legally blind person with 20/200 vision (with the best corrective lenses) must be within 20 feet of an object to see it, and a person with 20/20 vision can see it from 200 feet away.

Another way of looking at this is if someone with 20/20 vision were standing next to a person who is legally blind, for a legally blind person to see an object 200 feet away, as well as a person with normal vision, they would need to walk toward him as close to 20 feet as possible.

Low vision is a visual acuity of 20/40 or worse when corrective lenses are worn.

More than 4.2 million people over the age of 40 are officially blind or visually impaired, according to the Centers for Disease Control and Prevention .

line of sight

If a person has a field of vision of only 20 degrees, they can see objects directly in front of them without moving their eyes from side to side, but they cannot see anything from either side (peripheral vision). A 180 degree field of view is considered normal. A very limited field of vision is sometimes called tunnel vision . This makes it almost impossible to drive safely .


The ophthalmologist measures visual acuity and visual field to determine if a person is blind.

A common visual acuity test is the Snellen chart . Someone who is legally blind will only be able to read the top row of the table, capital E, while wearing corrective lenses. The line below the capital E is the 20/100 line. There are also tests that can measure from 20/200 to 20/100. Anyone who cannot see the 20/100 line but sees between 20/100 and 20/200 will still meet the government's legal blindness standard, thus it appears as "20/200 or less. "

Visual field tests often begin with a confrontational visual field test, in which you, the optometrist, cover one eye at a time and then lift one or more fingers in different quadrants of the visual field to test whether you can see them. while keeping your eyes open, focused on the center point in front of you. There are also more comprehensive computer tests that use blinking, blinking, or moving lights or images to measure the field of view. This includes pressing a button when you see light or images .


There are many conditions that can cause legal blindness, but age-related eye diseases are the most common. Age-related eye diseases, which are the main causes of low vision and blindness :

Injuries or trauma to the eyes, as well as genetic diseases such as Usher syndrome , can also lead to legal blindness.


Treatment for legal blindness depends on the cause and stage of the disease. For age-related eye conditions, prescription medications or eye treatments are commonly used to try to delay or prevent visual impairment.

For example, the goal of glaucoma treatment is to reduce pressure in the eye. This can be accomplished with prescription eye drops or oral medications, laser treatments, and, in severe cases, surgery to try to prevent further damage. It is important to closely monitor glaucoma and other age-related eye diseases to determine if treatment is working or needs to be adjusted.

Cataracts are an exception, as vision can be restored with surgery to remove the cloudy lens and, in most cases, replace it with an implant.

Get the word of drug information

It is clear that low vision or legal blindness can be limiting, but there are many resources and assistive devices available to help you live your life with maximum independence. Depending on the cause of your vision loss, eye exercises and strategies for participating in daily activities may be helpful. You can also use a cane, a talking calculator, special computer software, and other products designed to help people who have nothing to do with the law .

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