Children who have problems with reading, for whatever the reason, do better with larger font sizes like 14 and 16 points. This has nothing to do with visual problems, but because such children struggle with the process of reading, the larger font sizes forces eyes to move more slowly compared to standard-sized fonts. With bigger font sizes, students can easily follow their reading.
The amount of white space between the lines of print is called leading. There is no standardization for the font size and the leading between the lines among publishers. Leading in itself has no impact on legibility. It is the combination of leading with font size that can influence reading speed. For someone struggling with reading, specific legibility factors are important.
A study by Laura Hughes and Arnold Wilkins in 2000 concluded that typographical factors including font size, style and leading play a role in the development of reading. Font sze and leading usually decreases as children grow older. Small print can put a strain on the eyes. As the font size gets smaller, reading errors also increase, which led Hughes and Wilkins to conclude that larger and more widely spaced fonts enhanced speed and accuracy. Large print books, according to findings in 1987 by the Northland Library Cooperative in Alpena, Michigan, even help children with dyslexia read with success because of the additional space on the page in books.
A study at Wichita State University titled "The Effects of Font Type and Size on the Legibility and Reading Time of Online Text by Older Adults" also concluded larger font was reader-friendly. The study found that 14 point fonts were more legible to read than 12 point fonts. Participants in the research were people between the ages of 62 to 83 with the median age of 70 with no visual problems. Independent research by Elizabeth Lowe, a Maine-based literacy and neuroscience researcher, on the use of large print books by third and fifth graders also found an improvement of between 41 and 70 percent of student's SRA Reading scores after a year.