Here's the latest article from the Vision Issues site at BellaOnline.com.
Measuring Visual Acuity
Visual acuity is measured using a Snellen chart or other similar test, by counting fingers etc. It often is expressed as a fraction, such as 20/20 or 20/200. What do these numbers mean? Is 20/200 or 20/400 better? Is 20/20 vision really perfect vision?
http://www.bellaonline.com/articles/art53325.asp
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