What Is A 20/20 Vision
Posted at August 24, 2019
Know more about 20/20 vision and why it is said to be perfect. Read this in-depth discussion about vision.
When someone has perfect vision, they are often say that they have 20/20 vision. Why is that so? What makes this combination of numbers to be the so-called “perfect”? Is it possible to achieve vision that is even better than 20/20? And what is “perfect vision” anyway? Here is an in-depth discussion about the whole concept of perfect vision.
Before we dive into the whole 20/20 topic, we have to first understand the difference between these three terms: visual acuity and eyesight.
First off, visual acuity refers to the sharpness of your vision. If you’ve ever encountered those eye charts that have various letters in decreasing size, then you have an idea about it. These are called the Snellen chart or LogMAR chart. These are used to measure one’s ability to identify characters from a certain viewing distance.
Measuring visual acuity is a static procedure, meaning, you and the characters you are viewing are both stationary. Testing visual acuity is also done under high contrast conditions wherein the letters are black and the background is white. Because of these conditions, visual acuity tests can’t detect how well you would see objects in a bright background, coloured objects, and also moving objects.
There are three factors that determine visual acuity—cornea and lens focus, retinal nerve sensitivity, and brain interpretation capabilities.
Eyesight is simply defined as one’s ability to see. It can also be defined as “the sense of seeing”, “vision”, or “view”.
Knowing more about the 20/20 vision
The person responsible for the whole visual acuity measurement came from Herman Snellen. He is a Dutch ophthalmologist who came up with this measurement and the Snellen chart. The visual measurement is composed of two numbers—the former is the distance in feet between the test person and the subject, while the latter is the distance in feet that most people can see the subject.
Still confusing? Think of it this way. Let’s say you have 20/40 vision. At 20 feet, you can see the subject that most people can see at 40 feet. It’s that simple!
Is there something better than 20/20 vision?
If you think that 20/20 is already the best, then you are mistaken. Some people have 20/15 vision and some even better! It means that you can see things clearer from a farther distance (20 feet) while some people have to be nearer (15 feet).
Understanding your prescription
Refractive complications in the eyes can be expressed in numeric terms. The unit of measurement is called diopters. Upon receiving your prescription, you will see a set of numbers. These numbers are your diagnoses. The first number is the amount of myopia (-) and hyperopia (+). The second number, if present, pertains to astigmatism. The third is the axis of astigmatism, and the fourth number is the amount of magnification needed to achieve clear vision.
To know how sharp your eyes are, you may visit I-Vision for eye test at 79 Serangoon Garden Way Singapore 555975 or contact us at +65 6802 4726.