In the United States, legal blindness means that your central visual acuity, which is the part of your vision that allows you to see straight ahead, is 20/200 or less, even with glasses or contact lenses. This means that you can only read the first letter at the top of the Snellen Chart, if that. Additionally, you can be legally blind if you can see, but only in a very small window in your eye, and you cant see enough to function on a regular basis. It is important to note that legally blind is not the same as being totally blind. While legally blind people still might be able to see technically, people who are totally blind will not be able to sense light or see anything at all.