An eye exam revealing that your vision is 20/20 is good news. But what does it really mean? Read on as your trusted eye doctor explains more about 20/20 vision.
Measuring Your Visual Acuity
Visual acuity is a measure of how sharp your eyesight is. We usually measure visual acuity through a Snellen test, during which we’ll ask you to identify letters on the Snellen chart while standing 20 feet away.
Your expert eye doctor explains that each line on the Snellen chart has a corresponding fraction, like 20/20. The top number pertains to your viewing point when reading a specific letter, while the bottom number is the distance at which a person with a “normal” visual acuity can see the same letter clearly.
For example, if the test reveals your visual acuity is 20/70, this means you can see an image 20 feet away with the same level of clarity as a person with 20/20 vision would see if they were standing 70 feet away.
Common Refractive Errors
A visual acuity test can help your eye doctor detect signs of refractive errors. Myopia (nearsightedness) is a condition that causes you to have trouble viewing distant-range objects, while your close-range vision remains sharp. To illustrate, a person with normal visual acuity may be able to see items on the window display clearly at 20 feet. A person with myopia, however, would need to stand a few steps closer to be able to appreciate the same details.
Hyperopia (farsightedness) causes trouble with close-range vision. If you have hyperopia, you may need to take a few steps back to clearly see an object that’s directly in front of you.
Keep in mind that there are many different factors that affect your eyesight, and visual acuity is just one of them. While not perfect, 20/20 serves as the basis when it comes to measuring visual acuity and identifying refractive errors.
For more information about 20/20 visual acuity, call us at (425) 771-8472 for Alderwood Optical or (425) 485-0430 for Canyon Park Vision Clinic. You may also complete our form to request an appointment. We serve Redmond and Kirkland, WA, and nearby areas.