ConditionEyes & vision
Legal Blindness
Legal blindness is a legal definition, not a medical diagnosis. In the US, you are legally blind if your best-corrected vision in your better eye is 20/200 or worse, or if your field of vision is 20 degrees or less. Most legally blind people still have some useful vision. The definition determines eligibility for disability benefits, tax deductions and services. The leading causes in adults are macular degeneration, glaucoma, diabetic retinopathy and cataracts.
Also called: Statutory blindness, legally blind, severe visual impairment
At a glance
- US definition
- Best-corrected vision of 20/200 or worse in the better eye, or a visual field of 20 degrees or less.
- What 20/200 means
- You see at 20 feet what a person with normal vision sees at 200 feet.
- Most people can see something
- Only a small proportion of legally blind people have no light perception.
- Leading causes
- Macular degeneration, glaucoma, diabetic retinopathy, cataracts, inherited retinal disease.
- Why it matters
- Qualifies for Social Security disability benefits, tax benefits and vision rehabilitation services.
When to get help
Call 911 or go to the ER
- Sudden loss of vision in one or both eyes, a curtain over vision, or new flashes and many floaters
- Sudden vision loss with headache, jaw pain or scalp tenderness, especially over age 50
- Painful red eye with blurred vision, halos and nausea
See a doctor within a day or two
- Vision that is getting noticeably worse over days to weeks
- New distortion of straight lines or a dark spot in the center of vision
Book a routine appointment
- Gradual difficulty reading, recognizing faces, driving or seeing at night
- Diabetes, glaucoma risk or family history of eye disease without a recent dilated eye exam
- Living with low vision and wanting rehabilitation, aids or benefits advice
What legal blindness means
US federal law, used by the Social Security Administration (SSA) and the IRS, defines statutory (legal) blindness as:
- Central visual acuity of 20/200 or less in the better eye with the best possible correction (glasses or contact lenses), or
- A visual field limited to 20 degrees or less at its widest diameter in the better eye, sometimes called tunnel vision
Vision is measured with standard eye charts and visual field tests. Other countries use different thresholds. The World Health Organization defines blindness as vision worse than 3/60 (about 20/400) or a field under 10 degrees.
Legal blindness vs total blindness vs low vision
| Term | Meaning |
|---|---|
| Total blindness | No light perception at all. A minority of blind people |
| Legal blindness | 20/200 or worse, or field of 20 degrees or less, in the better eye with correction |
| Low vision | Vision that cannot be fully corrected with glasses, contacts, medicine or surgery and interferes with daily tasks, often 20/70 or worse |
| Visual impairment | Broad term for any vision loss that affects function |
Someone who sees 20/200 in one eye but 20/40 in the other is not legally blind, because the definition uses the better eye.
Common causes
Adults
- Age-related macular degeneration: loss of central vision, the leading cause in older Americans
- Glaucoma: gradual loss of side vision, can narrow the field to under 20 degrees
- Diabetic retinopathy: the leading cause in working-age adults
- Cataract: a leading cause worldwide, and reversible with surgery
- Retinitis pigmentosa and other inherited retinal diseases
- optic nerve damage from stroke, injury, multiple sclerosis or tumors
- retinal detachment and severe eye injury
Children
- cortical visual impairment from brain injury
- retinopathy of prematurity
- optic nerve hypoplasia
- inherited retinal and congenital eye conditions
How it is determined
An ophthalmologist or optometrist measures:
- Best-corrected visual acuity with an eye chart after refraction
- Visual fields using automated perimetry (such as Humphrey or Goldmann testing)
- Eye health through a dilated exam and imaging to identify the cause
For benefits, the SSA requires medical evidence from an eye specialist that meets its listing criteria.
Benefits and services in the US
- Social Security Disability Insurance (SSDI) and Supplemental Security Income (SSI): blindness has special rules, including a higher earnings limit for SSDI
- IRS additional standard deduction for people who are legally blind
- State vocational rehabilitation and services for the blind
- Library services: the National Library Service provides free talking books and braille
- Transportation: paratransit and reduced fares
- Education: IEPs and teachers of students with visual impairments
- Employment protections under the Americans with Disabilities Act
Living with legal blindness
Vision rehabilitation helps people make the most of remaining vision and stay independent:
- low vision aids: magnifiers, telescopes, high-contrast and large-print materials, good lighting
- technology: screen readers, magnification software, voice assistants, smartphone apps that read text or describe surroundings
- orientation and mobility training: using a white cane or guide dog
- daily living skills training: cooking, labeling, money handling
- emotional support: vision loss is linked to depression and isolation, and counseling and peer groups help
Legally blind people in the US cannot hold a standard driver's license. Some states allow driving with bioptic telescopes for people with vision close to the threshold, under specific rules.
Prevention
Many causes of vision loss can be prevented or slowed:
- regular dilated eye exams, especially after age 40, with diabetes, or a family history of glaucoma
- good control of blood sugar and blood pressure
- not smoking
- prompt treatment of macular degeneration with anti-VEGF injections
- cataract surgery when vision affects daily life
- eye protection at work and in sports
Frequently asked questions
What does legally blind mean?
In the US, legally blind means your best-corrected vision in your better eye is 20/200 or worse, or your visual field is 20 degrees or less. It is a legal standard used for benefits and services, and most people who are legally blind still have some vision.
Can you be legally blind and still see?
Yes. Most legally blind people have some remaining vision. Some see shapes and light, some can read large print, and some have good central vision but very narrow side vision. Total blindness, with no light perception, is uncommon.
Is legal blindness the same in both eyes?
The definition is based on your better eye. If one eye is 20/400 but the other sees 20/40 with glasses, you are not legally blind. Both eyes must be impaired enough that the better eye meets the criteria.
Can legal blindness be corrected?
Sometimes. Vision loss from cataracts can be reversed with surgery, and early treatment can stabilize macular degeneration or diabetic retinopathy. Damage from glaucoma, optic nerve disease and advanced retinal disease is usually permanent.
What benefits can a legally blind person get?
In the US, legally blind people may qualify for SSDI or SSI, an additional IRS standard deduction, state vocational rehabilitation, free talking books from the National Library Service, transportation help and other services.
Sources
This guide was written from current patient and clinical guidance, including:
- Social Security Administration: Disability Evaluation Under Social Security, Special Senses and Speech (Listing 2.00)
- American Foundation for the Blind: Key Definitions of Statistical Terms
- National Eye Institute: Low Vision
- American Academy of Ophthalmology: What Is Low Vision?
- Internal Revenue Service: Publication 501 (additional standard deduction for blindness)