The Snellen chart has eleven lines of block letters that anyone who are familiar with the alphabet should be able to recognize—that is, assuming they have the visual acuity to do so, as the letters grow progressively smaller as you proceed down the chart's lines. A line of print is 5mm high; thus, the largest letter in a line is 20/200 vision (since 2 minutes of arc equals 1 mm), and the smallest letter is 20/20 vision (0 minute of arc). The entire chart measures about 30cm by 45cm. There are two ways to interpret the lines on the chart. One method is to say that someone who can read the top line at 3 meters (10 feet) has poor vision, someone who can read the bottom line at 3 meters has good vision, and someone who can read any other line has vision equal to that reported by someone who can read the top line at 3 meters. The other method is to say that someone who can read the top line at 3 meters has perfect vision, someone who can read the next line down at 2 meters has better-than-normal vision, someone who can read the third line down at 1 meter has normal vision, and so on. For individuals with low vision, there are several options for improving their ability to see.