What is Legal Blindness?

“Legal blindness” is a definition used by the United States government to determine eligibility for vocational training, rehabilitation, schooling, disability benefits, low vision devices, and tax exemption programs. It’s not a functional low-vision definition and doesn’t tell us much about what a person can and cannot see. Having low vision means that even with regular glasses, contact lenses, medication, or surgery, you may find it difficult to perform everyday tasks. Part 1 of the U.S. definition of legal blindness states this about visual acuity:

Snellen eye chart
Eye Test Chart – Snellen Chart
  • Visual acuity of 20/200 or less in the better-seeing eye with the best conventional correction (meaning with regular glasses or contact lenses).
  • This is a 20/200 visual acuity measurement, correlated with the Snellen Eye Chart (pictured at left):
  • If you can only read line 1 (the big “E”) from 20 feet away while wearing your regular glasses or contact lenses, the doctor records your vision (or visual acuity) as 20/200 with the best correction.
  • Update: In 2007, the Social Security Administration updated the criteria for measuring legal blindness using newer low-vision test charts with lines that can measure visual acuity between 20/100 and 20/200. Under the new criteria, if a person’s visual acuity is measured with one of the newer charts and cannot read any of the letters on the 20/100 line, they will qualify as legally blind, based on visual acuity of 20/200 or less.

Part 2 of the U.S. definition of legal blindness states this about the visual field:

  • OR a visual field (the total area an individual can see without moving the eyes from side to side) of 20 degrees or less (also called tunnel vision) in the better-seeing eye.

A living room viewed through a constricted visual field.

A living room viewed through a constricted visual field.

Source: Making Life More Livable. Used with permission. For more information on the definitions of legal blindness, you can read Disability Evaluation Under Social Security, a publication from the Social Security Administration.

Using Low Vision Optical and Non-Optical Devices

Low-vision optical, non-optical, and electronic magnifying devices can make it possible for you to do a variety of everyday tasks, including

  • your favorite craft projects
  • preparing meals
  • and managing your finances

To learn more about the many different types of reading options that are available, see Reading and Writing Techniques.

Next Steps: What Can I Still Do If I Am Legally Blind?

Man using a screen magnifier to read.
  • You can still read.
  • You can still cook.
  • You can still work.
  • In other words, you can still enjoy life!
  • Read about Ben Karpilow, a low-vision attorney who practices disability law in California.

Visual Impairment

Much like low vision, there are many different definitions of visual impairment. “Visual impairment” is a general term that describes a wide range of visual functions, from low vision to total blindness.

Here is an example of the variations in the term “visual impairment” or “visually impaired” from the World Health Organization Levels of Visual Impairment:

Moderate Visual Impairment:

  • Snellen visual acuity = 20/70 to 20/160

Severe Visual Impairment:

  • Snellen visual acuity = 20/200 to 20/400
  • OR visual field of 20 degrees or less

Profound Visual Impairment:

  • Snellen visual acuity = 20/500 to 20/1000
  • OR visual field of 10 degrees or less

Like the term “legal blindness,” “visual impairment” is not a functional definition that tells us much about what a person can and cannot see. It is a classification system rather than a definition.

Light Perception and Light Projection

These terms describe the ability to distinguish between light and dark or daylight and nighttime. A person can have severely reduced vision and still be able to determine the difference between light and dark or the general source and direction of light.

  • The stereotypical assumption – that people who are blind or have low vision live in a type of “blackness” that sighted people see when they close their eyes – is generally inaccurate.
  • Although every person sees differently, including persons with low vision, an individual with light perception/projection can perceive the presence or absence of light. Some people describe light perception as knowing when a room light is on or off or being able to walk toward a lighted lamp on a table in an otherwise darkened room.

Total Blindness

Total blindness is the complete lack of light perception and form perception and is recorded as “NLP,” an abbreviation for “no light perception.”

Few people today are totally without sight. 85% of all individuals with eye disorders have some remaining sight; approximately 15% are totally blind.

Living room image source: From Maureen A. Duffy, Making Life More Livable: Simple Adaptations for Living at Home After Vision Loss (New York, NY: AFB Press, American Foundation for the Blind, 2015), p. 11. © 2015 by American Foundation for the Blind. All Rights