What Is Visual Acuity?
That familiar eye chart measures this aspect of your vision.
If you’ve ever had an eye exam, then you’ll remember sitting in a chair and covering one eye with a spoon-like tool while calling out rows of random letters. Whether you knew it or not, your optometrist was evaluating your visual acuity. Visual acuity is a measure of how well your eyes can tell distant objects apart from one another, which is one of the most important aspects of your eyesight.
How Is Visual Acuity Measured?
Optometrists measure your visual acuity using what is known as a Snellen chart. This is that large poster you see at every eye doctor appointment, memorable for the capital ‘E’ at the top of a pyramid of shrinking letters. A chair is placed exactly 20 feet away from the chart, where you sit and read off letters at your doctor’s direction. Since each eye is different, optometrists test one eye at a time, typically by giving you an occluder, a spoon-like tool that prevents all light from reaching your other eye.
20/20, 20/60, 20/200 – What’s the Difference?
We’ve all heard of 20/20 vision, but what does it actually mean? The first number is the easiest to remember, as it represents the distance between you and the chart (i.e., 20 feet). Therefore, with this measurement system, the first number will always be 20.
The second number represents the distance from which someone with normal (20/20) vision could read the last line that you read successfully. For example, if the last line you were able to read from 20 feet away was the line that someone with normal vision could read from 60 feet away, then the second number would be 60, and you’d be scored as having 20/60 vision.
How Common Is 20/20 Vision?
If you have 20/20 vision, then you can see things from 20 feet away that someone with normal vision can only see from up to 20 feet away. Although everyone would love to have 20/20 vision – and, for some, not having it can be a source of discouragement – it’s important to remember that only about 35% of the population possesses this level of visual acuity.
Is Visual Acuity the Ultimate Measure of Eyesight?
Visual acuity is by no means a complete assessment of your vision. Viewing the full picture of your eye health requires the measurement of many other visual skills, such as depth perception, peripheral vision, binocular vision, eye movement, etc. Only when all these factors are assessed can you really begin to understand the capacities of your sight.
Even though visual acuity is only one aspect of your eyesight, it is still important to keep your measurements up-to-date. Our optometrists at Sterling Vision excel at delivering comprehensive eye exams that accurately evaluate your visual acuity and much more. To schedule an appointment with us, call 541-262-0597 or schedule online.