Posts Tagged ‘20/400’

What Does 20/400 Mean

Monday, February 4th, 2013

We measure  your quality of vision at 20 feet-this is the numerator (top twenty).  The denominator (bottom 400) is a comparison to someone with standard vision.  So if you have 20/400 vision you would have to be at 20 feet to see what one with standard vision would see at 400 feet.

20/400 does not correlate to your exact prescription, it is merely a measure of your vision without (hopefully) your eyeglasses or contact lenses on.

By Dr. Cook, O.D.