What It Is, Qualifications & Common Questions

What does ‘legally blind’ mean?

“Legal blindness” is a term that defines severe vision loss. It isn’t a medical term. Instead, government agencies use it when determining how to apply policies relating to vision loss. If your visual acuity is equal to or less than the definition’s thresholds, you qualify as “legally blind.”

Total blindness is when everything appears dark (the technical term for this is “no light perception” or “NLP”). But only about 15% of people with eye disorders fall under that. The other 85% of people with eye disorders have at least some degree of functional eyesight.

The Social Security Administration (SSA) is the U.S. government agency responsible for the regulations surrounding legal blindness. They use a definition for legal blindness set by the American Medical Association in 1934. According to that definition, “legally blind” means at least one of the following applies:

• You have 20/200 (or worse) eyesight, even with correction. This means that even with glasses or contacts, you still have 20/200 eyesight or worse eyesight in the center of your field of view. If you have better sight in one eye, the measurement comes from the eye with the better vision.
• You have a field of view that’s no more than 20 degrees wide. If one eye has a wider field of view, the measurement comes from that better eye.

What does 20/200 mean?

If you don’t have 20/20 eyesight, the second number tells whether or not your eyesight is better or worse than normal:

• If the second number is smaller, you have better-than-normal eyesight. It means people with “normal” eyesight have to stand closer to see something as well as you can.
• If the second number is bigger, you have worse-than-normal eyesight. It means someone with normal eyesight can stand farther away and still see an object just as clearly as you can. In the case of 20/200 eyesight, that means you have to stand 10 times closer to an object or the object has to be 10 times bigger to see it as clearly as someone who has normal eyesight.

What is legally blind vs. blind?

The 20/200 threshold for “legally blind” is the only threshold set in the U.S. But some countries use other terms or define even more severe levels of vision impairment.

One example is the United Kingdom, which uses the metric system. For that country, 6/60 — about the same as 20/200 — means “sight impaired (partially sighted).” They also set a threshold at 6/150 — or 20/500 in feet — and define that as “severely sight impaired (blind).”

And many countries throughout the world rely on the World Health Organization’s International Classification of Diseases (ICD) for their legal thresholds. The 11th (and latest) edition of the ICD uses vision impairment categories, with three categories for “blindness.”

The ICD vision impairment and blindness categories use the following criteria: