Tiresias (typeface)

Tiresias is a suite of sans-serif typefaces designed specifically for people with impaired vision. Developed by Dr. John Gill of the Royal National Institute of Blind People (RNIB) in the United Kingdom, the Tiresias family aims to maximize readability for users with low vision, including those with cataracts, glaucoma, macular degeneration, and diabetic retinopathy.

The key characteristic of the Tiresias family is its focus on letterform distinctiveness. Designers paid careful attention to differentiating individual letters, ensuring that similar characters are easily distinguishable. This is achieved through features such as:

• Open counters: Generous space within enclosed letterforms (e.g., "a," "e," "o") to prevent filling in.
• Exaggerated ascenders and descenders: The parts of letters that extend above or below the x-height are made more prominent to aid identification.
• Wide apertures: Openings in letters like "c" and "s" are enlarged to improve clarity.
• Reduced stroke contrast: The difference in thickness between thick and thin parts of letters is minimized to prevent distortion.

The Tiresias family includes several variations tailored to different purposes. Some notable fonts within the family are:

• Tiresias Screenfont: Designed for on-screen use, optimized for clarity on computer displays.
• Tiresias Infofont: Intended for use in printed materials such as leaflets, signage, and reports.
• Tiresias Signfont: Specifically designed for wayfinding and signage, offering maximum legibility at a distance.

Tiresias fonts are often used in applications and environments where accessibility is paramount, such as public transportation signage, government publications, medical information, and assistive technology devices. Their widespread adoption reflects a commitment to making information more accessible to individuals with visual impairments.