The optometrist eye charts have been around for decades and are seen by millions of people worldwide. Here’s how we finalised the full alphabet and created a fully functioning typeface.
In the early 2000s, I was told to read out a set of letters arranged as a triangle on a chart in a health clinic in my local town.
I was told to start at the top with the larger letters:
“C, O, H, Z, V,” I said out loud. Then to the next line, with slightly smaller letters: “S, Z, N, D, C.” All good. When I reached the fourth line, I was struggling: “H… O…? K…?”
I was told I had astigmatism, which results in distorted or blurred vision at all distances, together with near-sightedness.
Of course, I didn’t know it at the time, but that was my first encounter with the Sloan typeface on a LogMAR eye chart.
Fast forward to early 2018. Working with brand identities, I was boarded onto a new brand identity project for an optometrist, Optician-K. The K stands for Krogh, a Norwegian family of optometrists who created their first optometry business in 1877.
As we usually do when working with new clients, we started doing research. This time, though, it was research on optometry, looking for a way to connect the Optician-K brand and their over 100-year history as optometrists to the craft of optometry.
As a graphic designer who works with type often, the old eye chart from the health clinic came to my mind. Were all clinics using the same typeface? Why does it look the way it does? Who made it originally? Can we use it in the identity?
An eye chart is used to measure visual acuity. And up until the 1800s, each ophthalmologist usually had their own preferred chart. A standardisation was needed to allow a patient to go from one eye doctor to another and get the same results.
Dutch ophthalmologist Hermann Snellen did just that in 1862. The chart was developed using characters drawn in a 5x5 grid. That means that the thickness of the strokes is the same as the white space in between the letters. The reason for this is a little more complicated. A standard placement for the chart is 6 metres from the reader. This makes the thickness of the lines and the white space between them subtend one minute of arc. That line (designated 6/6 or 20/20) is the smallest-letter line that a person with healthy visual acuity can read at the corresponding distance of 6 metres.
Based on the Snellen letters, Louise Sloan designed a new set consisting of 10 letters in 1959. These 10 letters are designed to be comparable to tests using the Landolt broken rings charts, another visual acuity system in which subjects identify the side of a broken ring where the break occurs.
The new Snellen letters were picked up by the National Vision Research Institute of Australia in 1976, when they developed the current standard for testing visual acuity today, the LogMAR chart. The LogMAR chart is relatable to the previously mentioned Snellen chart, with a Snellen score of 6/6 (or 20/20) corresponding to a LogMAR of 0.
After our research session, we found a way to tie the profession of the optometrist to the historical Sloan and Snellen letters. The problem was that the Sloan lettering only consisted of 10 letters in total — not even enough for us to make the logo.
So, we started drawing out the missing letters we needed. And then we got a little carried away…
To our surprise, we didn’t find any good, usable adaptation of the Snellen letters anywhere. So, we continued on the design that began decades ago and completed the full alphabet, including numbers and special characters. We got in contact with Portuguese typographer Fábio Duarte Martins, who immediately loved the idea and helped us tweak the font so that we ended up with a fully working typeface.
We had some discussions along the way about how true we should stay to the original 5x5 unit grid. Our typeface was developed to be a working display font, not simply letters to test visual acuity by a professional eye doctor. So, we made all the optical adjustments (pun intended) you’d expect in a modern typeface, while at the same time keeping things as close to the original letter forms as possible.
But we didn’t want to set those limitations on the typeface ourselves, so we included alternate glyphs for characters we felt needed a bit more adjustment than others. In the end, it’s up to the users to choose which they prefer.
To make things easy for our client, we programmed the logo into the typeface, eliminating the need for separate logo files altogether. So, if you write Optiker-K or O-K in this typeface, you’re getting the actual logo and pictogram for the optometrist that made this project possible.
We made the font available for free at optician-sans.com and are looking forward to hearing what you think about the project!