Criteria for Being Legally Blind

You've probably met someone who claimed to be legally blind or at least has heard or read the term somewhere. Although it may seem a little strange to label a health condition "legal," legally blind actually does refer to a definition of blindness recognized by government agencies and health insurers to determine if someone is eligible for certain benefits.

Departments of Motor Vehicles, which need a way of measuring how well potential drivers can see in order to keep our roads and highways safe, also use this definition.

According to the Centers for Disease Control and Prevention, more than 3.3 million people over age 40 are legally blind or have low vision. The main causes of blindness are related to age and include macular degeneration, cataracts, glaucoma, and diabetic retinopathy. 

Unlike those who are totally blind, meaning they can't see anything at all out of either eye, most people who truly are legally blind have some vision, according to the American Foundation for the Blind. 

To be considered legally blind, you would have to meet one of two criteria for visual acuity and visual field.

Visual acuity refers to how close a person needs to be to an object that's 20 feet away in order to see it in detail. Normal vision is measured as 20/20. If you had visual acuity of 20/80, it would mean that you would be able to see details from 20 feet away from the same as a person with 20/20, or normal, vision could see from 80 feet away.

A legally blind person with 20/200 vision (with the best corrective lenses) would need to be 20 feet from an object in order to see it as well as someone with 20/20 vision could see it from 200 feet away.

Another way to look at it: If someone with 20/20 vision was standing next to a person who's legally blind, in order for the legally blind person to see an object that's 200 feet away as well as the person with the normal vision he would have to get as close as 20 feet to it.

If you go for an eye test, you would only be able to read the top line, the big E, while wearing your corrective lenses.

If a person has a visual field of only 20 degrees, he can see things that are right in front of him without moving his eyes from side to side but he can't see anything on either side. By contrast, a visual field of 180 degrees is considered normal. A severely limited visual field sometimes is called tunnel vision. It makes it nearly impossible to drive safely.

Losing the ability to see can be scary, but it doesn't have to limit your ability to live your life. There are many resources and products for people who are legally blind—from canes and talking calculators to spill-proof cups and special computer software.

Even Amazon sells items that are designed for the legally blind. Certainly losing your vision will take a lot of getting used to, but it shouldn't stop you from doing almost everything you did when you could see.