Reading information from screens in one form or another will become a daily activity for most people. As digital television becomes available, our televisions and personal computers at home will develop into interactive terminals. The increase in access to the Internet is allowing a whole new level of interactivity between government offices, schools, colleges, medical centres, businesses and our own homes.

Reading a screen can be difficult for anyone under some circumstances such as bright sunlight. However, the problems are more severe for elderly and visually impaired people. The choice of typeface can make all the difference to screen legibility.

Visual impairment is much more common than many people think. It is estimated that the majority of the population have problems reading text on screens.

When a typeface is projected onto a screen the character shapes are created on a grid of fine lines or pixels. Because most traditional typefaces were designed for reproduction on paper rather than screens their subtle shapes are distorted when viewed on screen, particularly at small sizes.

Some typefaces are fairly legible on screens but many are not. To help improve the legibility of type on screens, the Tiresias Consortium, under the direction of Dr John Gill of the Royal National Institute of the Blind, have designed Tiresias PCfont.

Tiresias PCfont is in the same family as Tiresias Screenfont but has been specially designed to reproduce to an optimum resolution at most sizes on screen pixel structures.

PCfont has a slightly condensed character shape. These proportions have been chosen to allow the maximum number of characters per line without losing legibility. The individual letter shapes have then been designed to display clear shapes within the available grid for each type size.

Careful thought has been given to the letters and numerals so that persons with low vision can distinguish characters such as the lower case 'l' from the numeral '1' and the capital 'I'. This is particularly important now that more unusual combinations of letters and numerals are being used in Email: addresses.

When the typeface is used it will be seen that at small sizes some sizes display slightly better than others. The user should adjust the size to suite the available space and viewing conditions depending on the viewing environment. Guidelines for improving legibility on screen based systems can be viewed from this link.