Legally Blind: What Does it Mean?

Although most people can define complete blindness, many do not understand, or even know, that there is a difference between total blindness and legal blindness. There are approximately 12 million people in the United States who have a visual impairment. This includes 3 million people who would be considered legally blind. 

To be legally blind means a person’s vision cannot be corrected, even with eyeglasses or contact lenses. Unlike complete blindness, where the person does not see any light or shape, people who are deemed legally blind may be able to make out shapes or see some light. In Canada and the United States, a person is considered legally blind based on two criteria: their visual acuity and field of view. 

An individual with a visual acuity of 20/200 or less, in their better eye when best corrected, is considered legally blind. Visual acuity is typically measured using a Snellen Chart. If you have ever visited an optometrist or ophthalmologist, you’ve probably had to identify the letters on the chart. Each line corresponds to a certain level of visual acuity, with the letter sizes decreasing as you go down the chart.

The eye chart assumes the base distance of 20 feet. A person with normal vision (20/20 visual acuity) can identify all the letters when standing 20 feet away. However, having 20/200 visual acuity means that the person needs to be 20 feet away from the chart to see what others can see when 200 feet away.

legal blindness, peripheral vision

Individuals with a severely restricted field of vision, no more than 20 degrees, can also be considered legally blind. A person might see the smallest letters on the chart, but fail to see an object next to them. This is the result of a significant decrease in peripheral vision.

Two parameters are measured when it comes to peripheral vision: vertical and lateral. The maximum lateral field of view a person can see is 180 degrees. This means there is no difficulty seeing objects to their right and their left, simultaneously. The maximum vertical field of view is 135 degrees, meaning an individual can see what is directly below their feet and above their head at the same time.

What Causes Legal Blindness? 

Several eye conditions can cause a person to be considered legally blind. For some, it is congenital, while others might develop a condition later in life. The four leading causes in the United States are: 

  • Age-related macular degeneration
  • Cataracts
  • Glaucoma 
  • Diabetic retinopathy 

Other causes of legal blindness include optic neuritis and neuropathy, retinopathy of prematurity, and Stargardt’s disease.

How can eSight help?

eSight is a class 1 medical device that’s been proven to work for over 20 different eye conditions. It has also worked for individuals with visual acuities from 20/60 to 20/800. These conditions include: 

eSight 4
  • Macular degeneration
  • Glaucoma 
  • Cataracts
  • Age-related macular degeneration
  • Retinopathy of prematurity 
  • Optic Neuropathy
  • Stargardt’s Disease 
  • Diabetic retinopathy
  • And many more 

eSight works by providing additional stimuli to the dormant photoreceptors in the eyes, allowing them to receive more visual information than they usually do. The device features the best match camera and lens technology that projects high-quality images onto two high-resolution screens for full binocular vision. 

eSight has helped thousands of people with legal blindness see and experience new possibilities. Read the stories of the many individuals eSight has helped here

See what’s possible with eSight. Speak to an eSight advisor today.

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