<sod>The common Snellen chart is printed with eleven lines of block letters. The first line consists of one very large letter, which may be one of several letters, for example E, H, or N.  Subsequent rows have increasing numbers of letters that decrease in size. A person taking the test covers one [[human eye|eye]] from 6 metres or 20 feet away, and reads aloud the letters of each row, beginning at the top.  The smallest row that can be read accurately indicates the visual acuity in that specific eye.<eod>
<sod>The common Snellen chart is printed with eleven lines of block letters. The first line consists of one very large letter, which may be one of several letters, for example E, H, or N.  Subsequent rows have increasing numbers of letters that decrease in size. A person taking the test covers one [[human eye|eye]] from 6 metres or 20 feet away, and reads aloud the letters of each row, beginning at the top.  The smallest row that can be read accu  <eod>