We often hear that "hindsight is 20/20" or someone proudly boasting of their 20/20 vision. Now, with 2020 firmly in hindsight, we can ask, what does "20/20 vision" mean? Is it something to brag about? Is there a better way to measure visual acuity than that odd number? Michigan Eyecare Institute in Southfield, MI, brings optometry into focus.

What Is 20/20 Anyway?

In 1862, Herman Snellen, a Dutch ophthalmologist, invented an eye chart that we still use today in optometry and eye exams. The chart shows a series of small letters on a blank background, and its goal is to determine the smallest letter that the eye can make out. Originally, the chart was printed to be readable by average vision at a distance of 20 feet. Thus, we have the first "20" in 20/20. The second "20" means that you can read the row marked "20" at a distance of 20 feet. Therefore, "20/20 vision" does not mean "exceptional," but rather it means "as expected." As expected, you can read the chart at the distance prescribed.

During World War II, the best pilots could focus on "infinity." They could see things so far that other pilots couldn't match them. Men like Chuck Yeager and Clarence "Bud" Anderson had eyesight graded by an optometrist as "20/10" or even "20/5" - they could see objects at 20 feet that most people would need to be within 10 or 5 feet to see.

Distance

Because eye exams are typically not performed in offices with walls 20 feet away (consider the space costs in a mall storefront), charts are scaled with either a mirror to project them the correct distance away, or in modern offices, they are digitally projected at a distance that makes them "virtually" 20 feet away for proper measurement. However, an eye exam fundamentally depends on a subjective measurement by the patient: What distance vision is the patient comfortable with?

Contact Your Eye Doctors at Michigan Eyecare Institute

If it's been a while since your last eye exam, consider scheduling one with one of our optometrists in Southfield at Michigan Eyecare Institute. Call (248) 352-2806 to schedule an appointment or contact us through our website by using our online contact form.