Legal Blindness Explained

Many people assume "legally blind" means complete blindness, but the truth is more nuanced. In fact, most individuals who are legally blind still retain some level of vision. The term is actually a legal classification used in the U.S. to determine eligibility for disability benefits and access to essential services not a medical diagnosis of total blindness.

So, what does it really mean to be legally blind? Here’s what you need to know.

The Legal Definition of Blindness

In the United States, a person is considered legally blind if they meet one of the following criteria in their better eye, even with corrective lenses (like glasses or contacts):

• Visual acuity of 20/200 or worse, meaning what a person with normal vision can see clearly from 200 feet away, someone who is legally blind can only see at 20 feet.

• Visual field of 20 degrees or less, also known as tunnel vision, meaning you have very limited peripheral vision.

This definition is used by government programs like Social Security Disability Insurance (SSDI) and Supplemental Security Income (SSI) to determine whether someone qualifies for disability support. It also plays a role in tax deductions, access to assistive services, and even driving eligibility in some states.

How Is Legal Blindness Diagnosed?

Two standard in-office eye tests are used to diagnose legal blindness:

• Snellen Eye Chart Test: You’ll be asked to read rows of letters of decreasing size. A legally blind person can typically only read the top line (a large "E"), even with corrective lenses.

• Visual Field Test: One eye is covered while the other is tested for peripheral vision. If your visual field is 20 degrees or less, you meet the criteria for legal blindness.

Additional vision tests may be used for more detailed assessments, but these two are enough to confirm a diagnosis for legal or disability purposes.

Is Legal Blindness the Same as Total Blindness?

Not at all. Total blindness, meaning no light perception, is rare. In fact, around 85% of people classified as legally blind still have some usable vision. This might include light sensitivity, shapes, or motion detection enough to function with assistive technology or mobility aids.

Legal Blindness vs. Medical Blindness

While “legal blindness” refers to eligibility for benefits, “medical blindness” covers a broader spectrum of visual impairments.

According to the World Health Organization (WHO), vision is categorized into levels:

• 20/40: Mild impairment

• 20/70: Moderate impairment

• 20/200: Severe impairment

• 3/60 or worse: Considered blind

• No light perception: Total blindness

So, someone with 20/200 vision or worse may be legally blind but still retain some visual capacity.

What Is Low Vision?

Low vision refers to vision loss that can't be corrected by glasses, contacts, medication, or surgery but isn’t severe enough to be classified as legally blind. From a clinical standpoint, it usually means vision of 20/70 or worse in the better eye.

Legally, however, definitions vary by state. In some areas, individuals with low vision may still qualify to drive under certain conditions, while others may have stricter limits.

Benefits of Legal Blindness Certification

If diagnosed as legally blind, your doctor may issue a Certificate of Legal Blindness, which can help you access:

• Social Security Disability benefits (SSDI or SSI)

• Medicaid coverage

• IRS tax deductions for blindness

• Educational accommodations and scholarships

• Housing and transportation assistance

• Subsidies for assistive technology and telecommunication devices

• Guide dog support and mobility training programs

These services are designed to help individuals with vision loss maintain independence and quality of life.

Understanding 20/20 Vision

To put things in perspective:

• 20/20 vision means you can see clearly at 20 feet what someone with normal vision should see at 20 feet.

• 20/200 vision means you’d need to be 20 feet away to see what most people can see clearly from 200 feet away.

Corrective lenses may improve vision for some, but once you've reached the legal thresholds (with correction), you’re considered legally blind.

Key Takeaways

• Legal blindness is defined as 20/200 vision or worse, or a visual field of 20 degrees or less, in the better eye with correction.

• Most legally blind individuals are not totally blind they retain some degree of sight.

• This classification allows individuals to qualify for government and local services, from disability income to tax breaks and assistive technology.

• Diagnosis involves simple eye tests performed by an optometrist or ophthalmologist.

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