Thursday, September 10, 2015

Optotype: Typography of the Eye Chart

      At this point in the game everybody has seen this image at one time or another, but what exactly are the origins of this modern icon? It wasn't until the advent of Gutenberg's printing press that levels of literacy were raised all across Europe.  In 1836 ophthalmologist Heinrich Kuchler designed the first standardized chart that used snippets of existing copy from books, calendars, and small recognizable symbols of the period. Kuchler continued his work in and created a rendition of his chart seen below:
Twelve rows of type in descending size were printed but unfortunately it was in blackletter and ridiculously illegible especially at smaller sizes. It was introduced in 1843 and was discontinued soon after. 

      Today's eye chart was created by Dutch opthalmologist Herman Snellen in 1862. Originally Snellen experimented with visual symbols and entire sentences of text but patients eventually caught on and assumed the ending of the phrase. He later boiled down the sentences down to individual characters and randomized the order of presentation to create a purely objective test.  The characters included were A, C, G, L, N, P, R, T. 5, V, Z, B, D, 4, F, H, K, O, S, 3, U, Y, A, C, E ,G and L. He used slab serif letterforms as a base for his optotype system.  He theorized that subjects would be able to identify equal weighted letters of consistent size and created an entire typeface in a unique grid system. Instead of picas or points he based his grid on arcminutes: a measurement system in medicine  which are equal to one sixtieth of a degree.

In 1863 Snellen's chart pattern was used by the British military as a standardized test for incoming recruits. Ever since, different iterations of optotype fonts and varitions have been introduced but Snellen's original chart system is continued use to this day. 

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