I found this thorough and informative post this morning. It gives a basic overview of what the term “20/20 vision” actually means. An excerpt:
If your visual acuity is determined to be 20/20, you see at 20 feet what a person with normal vision sees at 20 feet. If you have 20/40 vision, you see at 20 feet what a person with 20/20 vision would see at 40 feet. And, if you’re one of the lucky ones (e.g., 20/15), you can see at 20 feet what others would have to move closer (15 feet) to see.
Check it out. In case you’re wondering, my uncorrected vision is about 20/800. This prohibited me from becoming a Coast Guard Engineer. What’s your uncorrected vision?