Understanding 20/20 Vision and Visual Acuity

We've all run into the expressions 20/20 vision and visual acuity. But do people understand what these terms actually mean?

The term 20/20 indicates the sharpness of your eyesight measured at a distance of 20 feet. If you have 20/20 eyesight, that means that from 20 feet away you're able to accurately see that which normal-sighted people can see from that distance. So, 20/100 eyesight indicates that to see what most people can see from 100 feet, you would have stand as close as 20 feet away. Obviously, if this was the situation, it would mean that you would be extremely near sighted.

Each one of your eyes is tested separately. During the part when you're asked to read the letters on the eye chart aloud, the smallest row that you can read properly determines the visual acuity in the eye being evaluated.

But 20/20 eyesight doesn't necessarily mean that your eyesight is totally free of flaws, because, after all, it can only judge how well you see at a distance. There are several other crucial sight skills; your ability to focus on close objects, contrast sensitivity, peripheral vision, depth perception, eye coordination and color vision - these also contribute to your overall vision. Also, a patient with 20/20 vision can still have unhealthy eyes. Even people who have damage to the retina due to diabetes, high blood pressure, glaucoma, or a range of other diseases are still able to have 20/20 vision without needing to wear eye glasses. And because of this, an eye care professional always conducts a comprehensive eye exam, rather than just a simple eye chart exam.

When you're having your next eye exam, you'll know exactly why you need to read letters from the eye chart, and more!