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 ...

For instance, there are charts created for people who don’t read Latin script and there are visual-acuity charts that use different symbols, such as a house or apple, or varying orientations of ...

At least once in your life, you must have squinted at the eye chart at the doctor’s office or DMV, trying to make out the blurry bottom line. Turns out, there’s some very precise math that ...