Optician Sans is a free optotype 1 based on the Sloan letters2.

  1. I had no idea this was a thing. There’s a lot to learn here about the eye charts I see once a year. The earliest chart appears to go all the way back to 1862 (!) Those little "C"s are called Landolt C. The one most optometrists use these days is called a LogMAR Chart which measures visual acuity as a log function of the smallest visual angle your eyes can resolve. ↩︎

  2. Which you can download here with “noncommercial research” in mind. ↩︎