Low vision often makes reading a difficult task in the following situations:
- When a diminished amount of light can come in the eye
The contrast of the print on its background is affected by diminished light and blurring. The harm to the central retina interferes with the capability to see petite print, and to make necessary eye movements involved in reading.
The following guidelines make print more legible for individuals with vision problems and for the general public as well. Therefore, they are significant for universal design.
Large print type should be used, preferably Eighteen point, but at a minimum 16 point. Scalable fonts on the computer make this effortless to do.
Font Type and Style
The objective in font selection is to use lightly recognizable characters, either standard Roman or Sans Serif fonts. A good choice is Arial.
Use of Color
The use of different colored lettering for headings and emphasis is difficult to read for many people with low vision. When used, dark blues and greens are most effective.
Contrast is one of the most critical factors in enhancing visual functioning, for printed materials as well as in environmental design. Text should be printed with the best possible contrast. For many older people light lettering—either white or light yellow—on a dark background, usually black, is lighter to read than black lettering on a white or light yellow background.
Avoid using glossy finish paper such as that typically used in magazines and some journals. Glossy pages create excess glare, which makes it more difficult for people with low vision to read.
Leading (Space Inbetween Lines of Text)
The recommended spacing inbetween lines of text is 1.Five, rather than single space. Many people who are visually impaired have difficulty finding the beginning of the next line when single spacing is used.
Tracking (Space Inbetween Letters)
Text with letters very close together makes reading difficult for many people who are visually impaired, particularly for those who have central visual field defects, such as older persons with macular degeneration. Spacing inbetween letters should be wide—for example, a mono-spaced font such as Courier, which allocates an equal amount of space for each letter, is very readable.
Many low vision devices, such as stand magnifiers and closed-circuit televisions (CCTVs) are easiest to use on a plane surface. An extra-wide roping margin makes it lighter to hold the material plane. A minimum of one inch should be used; one and a half inches is preferable.
Research is still underway to determine how text can be made more legible for individuals with limited vision.