Vision or visual acuity is tested by reading a Snellen eye chart at a distance of 20 feet. If you have 20/20 vision that means when you stand 20 feet away from the chart you can see what a “normal” human being can see at 20 feet. If you have 20/40 vision, it means that when you stand 20 feet away from the chart you can only see what a normal human can see when standing 40 feet from the chart. So the top number represents the distance you stand from the chart, and the bottom number is the distance a person with normal vision could read the same line you correctly read. So the larger the bottom number is, the worse the vision is.
In addition, if you have vision that is better than the norm such as 20/10 vision, that means you can see at 20 feet what a normal person can see when standing 10 feet away from the chart.
Fun fact – a hawk’s vision is eight times more acute than a human’s, which means they might have 20/2 vision!
Legal blindness in the United States is considered to be 20/200 vision.
DMV’s Vision Screening Standards are:
- 20/40 with both eyes tested together and
- 20/40 in one eye and
- 20/70, at least in the other eye
The better we can correct your vision the safer you will be on the road.