Optical devices are used for orientation and mobility. They are also used for reading time tables, reading directories in buildings, reading addresses, maps, etc. Children shouldn't have to wait for someone to produce large type for them. Large type texts are bulky and don't at this time have color which makes the books less attractive and some directions to children rely on children being able to see color in pictures that go along with text. When large print is produced, labels on diagrams, fractions, map markings, etc.
Optical devices allow a child to gain control over their visual environment.
Optical devices give students more practice at reading because they can read more in their environments. Any child who can read 18 point print can read using optical devices. Optical devices can increase visual environmental awareness. Optical devices have vocational and recreational applications that expand opportunities to use print. I strongly believe there are increases in literacy skills, e.g., increases in reading speeds with practice with optical devices - over reading speeds using large type.