Many people believe that 20/20 vision is the same as a perfect vision. However, while seeing in 20/20 means you have good visual acuity, you need many other eyesight skills—including depth perception, peripheral awareness, eye coordination, focusing ability, and color vision—to see well. Find out more about visual acuity and why everyone needs routine eye exams, even if you have 20/20 vision.
How Is Visual Acuity Measured?
Visual acuity—or sharpness and clarity of vision—is measured by your ability to read letters on an eye chart from 20 feet away. This technique has been used since 1862 when Dutch ophthalmologist Herman Snellen developed the Snellen eye chart. Visual acuity measurements, including 20/20, are also called Snellen fractions.
Is 20/20 the Best Vision You Can Have?
Most people strive for 20/20 vision, but this is not the best vision you can have. For instance, if you can discern the letters on a Snellen chart below the 20/20 line without stepping any closer, you have 20/15 vision. This means someone with 20/20 vision would have to get within 15 feet to read those letters. 20/10 vision is also possible, indicating visual acuity twice as sharp as standard 20/20 vision.
Why Do Some People Have Less Than 20/20 Vision?
When the second number in a Snellen fraction goes higher than 20, this signifies poor visual acuity. For instance, 20/40 vision means you have to stand within 20 feet of an eye chart to read what someone with normal vision can see from 40 feet back. Interestingly, this is the visual acuity required to pass a driver’s license test.
If everything except the big “E” at the top of the chart is blurry from 20 feet away, you have 20/200 vision. At this level, you are considered legally blind and need glasses or contacts to function in your day-to-day life.
Snellen charts are effective at measuring myopia (nearsightedness), or difficulty focusing on far-away objects. However, they don’t address hyperopia (farsightedness), or difficulty focusing on things up close. Presbyopia, or the gradually declining ability to focus on up-close objects, is another condition an eye chart can’t measure. Other conditions, such as astigmatism or eye disease, can also affect visual acuity at different ranges.
Who Needs Eye Exams?
Even if you’ve had 20/20 vision all your life, eye diseases like cataracts, glaucoma, and macular degeneration can sneak up on you without warning. Regular eye exams help you discover these problems early, so you can take action when they’re easier to treat. That’s why everyone should visit the eye doctor at least once every year or two.
If it’s been a while since your last eye exam, reach out to Windsor Eye Care & Vision Center. We offer a full range of optical care, including routine eye exams, contact lens fittings, and eyewear services. Our goal is to enhance your quality of life by improving your eye health and vision. To enjoy compassionate care, state-of-the-art technology, and exceptional patient service, please contact us today.