Vision

Understanding 20/20 Vision Update

This is a post originally for about 2 years ago, that I thought it would be good to update.

People ask me what Will sees, while I can’t give an accurate picture of that, I thought that giving some perspective on the distance he can read would be good. As he is approaching Kindergarten in the fall we are really trying to understand at what distance he can accurately read and see the board.

In March he read letters from the 20/80 line, which is the first time he has ever seen anything on a standard eye chart. Below is an illustration of what he could read verses a “normal” 20/20 vision person. He can read at 20 ft., what “normal” 20/20 vision people can read at 80 ft.

vision compairsion

We all hear references to 20/20 vision, but what does that really means? I was talking with a friend and realized even I couldn’t accurately articulate it after all we have been through. So here is an explanation.

Over time, eye doctors established what “normal” people should be able to see at a distance of 20 ft. At the doctor’s office they test us with eye charts containing letters at a simulated distance of 20 feet and if you can see the appropriate line, then you have 20/20 vision. Or you can have your vision corrected to 20/20 using glasses or contacts. Keep in mind, this is considered “normal” vision.

People with 20/40 vision can see at 20 feet what people with “normal” vision can see at 40 feet. A person with 20/100 vision can see at 20feet what people with “normal” vision can see at 100 feet. It is important to remember that 20/20 vision isn’t considered perfect vision, it is considered normal vision.

It is also possible for people to have better than “normal” vision, such as 20/10 or 20/15. That means that those people see at 20 feet what people with “normal” vision would see at 10 or 15 feet.

In the United States, people with vision 20/200 or higher are considered legally blind. I was actually considered legally blind before my LASIK surgery and without my glasses or contacts. Unlike Will’s condition that affects the back of the eye (retina), my vision deficiency was due to a lens defect so it was correctable. Typically you need to have 20/40 vision using eyes together to pass driver’s vision exams around the country.

Hopefully it will help put it in terms that make sense and are easier to visualize. Although I would love a program that could really show me what he really sees.

Sources:

http://health.howstuffworks.com/human-body/systems/eye/question126.htm

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