I love Typography ILT. July 1. 2, 2. 01. HGZqa6-f3FQ/U-yEVMLLP5I/AAAAAAAAAtE/rjKYvru88Yc/w1200-h630-p-k-nu/arsenal%2B2014%2B2015%2Bfont.jpg' alt='Fonts 2015' title='Fonts 2015' />Lorrie Frear. I started my quest by asking my ophthalmologist, who enthusiastically provided a dizzying amount of technical information about the variety of eye charts and tests designed for different audiences and eye conditions. Suddenly, a simple question became a series of discoveries. Not only is there not one letterform design or font used for eye charts the letterform designs are more appropriately called optotypes, of which there are several versions. There is a science to the design of optotypes and their legibility at specific distances. Since I am a graphic designer and not an eye or vision expert, I will forgo the technical explanations and focus on optotypes used on several significant charts to provide a better understanding of this complex and fascinating subject. Eye charts are designed to test visual acuity, or clarity of vision. Each chart design has limitations and advantages, depending on the clinical setting, patient profile, and diagnostic objective. To understand the differences between the charts, it is helpful to know a little historical background of standardized visual acuity testing. The First Standardized Tests. Figure 1 Kuchler Chart. Heinrich Kchler is one of the first individuals credited with creating an eye chart to test visual acuity. Kchler, a German ophthalmologist, designed a chart in 1. These figures included cannons, guns, birds, farm equipment, camels, and frogs. Boost your branding projects with our goto list of best logo fonts. DZPkLdk/VgOtdYNjnvI/AAAAAAAAFXw/wb1JZXPOQ_8/s1600/Arsenal%2BUCL%2BUEFA%2BChampions%2Bleague%2B2015%2B2016%2Bfont%2Bttf%2Botf.jpg' alt='Fonts 2015' title='Fonts 2015' />Based on a German website, these are the top 100 best fonts of all time. Check out these top 100 Best, Cool, Most Popular Professional Fonts In English. Free_Fonts_2015_Typefaces.jpg' alt='Fonts 2015' title='Fonts 2015' />
This system was limited because the figures were not consistent in visual weight or style. Dr. Kchler continued to refine his chart, and in 1. Blackletter letters decreasing in size. This chart was not widely adopted hard to imagine why and was published only once in 1. Figure 2. Snellen Chart. The next significant development in visual acuity chart design was the Snellen Eye Chart, which is recognizable to most Americans from visits to the DMV. The Snellen Eye Chart was designed by Dutch ophthalmologist Herman Snellen in 1. This test had obvious limitations the results were dependent upon the reading ability of the patient, the legibility of the typeface used, and the fact that the patient could guess the next word by reading a sentence. According to Dr. August Colenbrander, a scientist at the Smith Ketterwell Eye Research Institute and an expert on eye chart design, Snellen began experimenting with dingbats, or symbols such as squares and circles for his eye chart, but found that it was difficult for test subjects to describe the symbols accurately. So, he moved on to using letters. The characters on the first Snellen Charts were A, C, E, 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. The letters used were Egyptian Paragons or slab serifs of contrasting line thickness with ornamental cross strokes on terminals. Snellen then theorized that test subjects would be able to identify non ornamented, monolineequally weighted letters of consistent visual size more easily, and so he created optotypes. Figure 3. Snellen vs Lubalin Graph. Letter Writing Software there. At first glance, it may appear that the Snellen optotypes are Lubalin Graph or Rockwell. But upon detailed examination, it is evident that these characters are rather atypical. Unlike typical typefaces in which letter proportions are determined by family groupings such as n, r, m, h and u, Snellen optotypes are designed on a 5 x 5 grid. Furthermore, they comprise a very limited character set of just 9 1. Optotypes are designed using a simple geometry in which the weight of the lines is equal to the negative space between lines. The height and width of an optotype is five times the thickness of the line weight. These design considerations create inconsistently and oddly proportioned letters. For example, in a typical typeface, C and D would appear wider than Z, but in the optotype scheme, the opposite is true. Figure 4. Snellen letter EDr. Snellen created Optotypes using minutes of arc instead of a typographic measuring system. This made it possible for his charts to be reproduced easily. The first large order for Snellen Charts was from the British Army in 1. From there, the Snellen Eye Chart became the standard for vision testing for almost a century. In addition, Snellens 5 x 5 grid optotype design is the foundation upon which all other eye chart systems are based. The Snellen Eye Chart is still the most recognized design, which can, to some extent, negate its effectiveness, if, for example, the test subject has memorized the chart. Most Snellen Charts contain eleven lines of block letters. The first line consists of a single large letter, most often an E. Subsequent rows have increasing numbers of letters that are progressively smaller in size. The test subject, from a distance of 2. The smallest row that can be read accurately indicates the visual acuity in that particular eye. Current Snellen Charts use nine letters, C, D, E, F, L, O, P, T, Z. Note that with the exception of E and O, the letters are all consonants. The diverse shapes of the optoypes allow test subjects to identify verticals, horizontals, and diagonals. These letter shapes are also highly effective in identifying astigmatism. Although todays Snellen Eye Charts may vary in the number of rows, size gradation, and serif or sans serif design,7 their commonalities include the rectangular shape. This dictates the varying numbers of optotypes appearing on each line as space permits. As a result of continual refinements, most of todays Snellen Charts follow logarithmic progression, have improved letter designs, and a uniform 2. Refinements and Variations. In 1. 86. 8, Dr. John Green of the St. Louis College of Physicians and Surgeons in Missouri decided to make some changes to the Snellen Eye Chart. He designed a more structured grid featuring a consistent logarithmic geometric progression of 2. He also changed the style of the optotypes from the blocky slab serif to sans serif. His concept became known as the Preferred Numbers Series, but his system did not become widely recognized until the next century when sans serif typography gained popularity. Ironically, in response to criticism that his letters looked unfinished, Dr. Green abandoned them in 1. Figure 5. Sloan Chart. In 1. 95. 9, Dr. Louise Sloan of Johns Hopkins University created ten new optotypes using sans serif letters preferred by Dr. Green. These optotypes included the letters C, D, H, K, N, O, R, S, V, and Z. Like Snellen letters, Sloan Letters are formed within a square, with the stroke width equal to one fifth of the letter height and with equal visual weight. The Sloan Chart has consistent spacing between letters and rows that are proportional to letter size. Spacing between letters is equal to letter width, and spacing between rows is equal to the height of the letters in the subsequent, smaller row. Notice that, as in the Snellen Chart, all of the characters are consonants with the exception of 0. Also note that the letter selection used on the Snellen Chart is not the same as that in the Sloan Chart. In both cases, the diverse shapes of the optoypes allow test subjects to identify verticals, horizontals and diagonals an aid to identify or differentiating individual letters. The ten Sloan Letters are considered to be the most effective letter selection for equal legibility. Whats more, they are particularly effective at identifying astigmatism.