Fig. 16. Reading card with proportional paragraphs. All paragraphs on this chart have the same length so that reading times and reading fluency can be compared. The set of smaller paragraphs is duplicated to avoid memorization. A ruler with a diopter scale is provided to compare the reading distance to the reading add and to facilitate the use of the modified Snellen formula (1/V = M × D). Various languages are available. The same text appears on the back of the chart in Figure 9.