Should we know exactly what the chart is for reading letters when we go for an eye test? (Visual Acuity Test)

Have you ever gone to a doctor to get your eyes checked? You probably remember when you went, they would make you sit in a chair, hang a big chart on the wall a little distance away, and ask you to read the letters on it one by one. You have to read from the top letter to the smallest letter, line by line. Sometimes you have to close one eye, then the other... That's the very simple test that we all know, which is medically called a Visual Acuity Test . Simply put, it checks how sharp your eyesight is . Today, we're going to talk about this in a little more detail , as if you were talking to a friend.

What exactly is this Visual Acuity Test?

Visual Acuity simply means "clearness of vision" or "sharpness of vision". It refers to how clearly you can distinguish shapes and details from a certain distance. When you are walking down the street, can you clearly read the letters on a sign that is far away? Can you see the number on the bus from a distance? Things like that are determined by your visual acuity.

So this test is the quickest and easiest way for a doctor to see if your vision has changed over time. It's the first and most important step in an eye exam.

Why is this test so important?

This simple test can detect many common problems with our eyes early. In particular, it is used to identify four main problems known as refractive errors.

• Nearsightedness / Myopia: This is when you can see things that are close to you clearly, but things that are far away are blurry. For example, reading a book is fine, but watching TV or seeing a number on a bus on the road is blurry.
• Farsightedness / Hyperopia: This is the opposite of the previous condition. Although distant objects can be seen clearly, nearby objects, especially when reading a book or newspaper or looking at a phone, appear blurry. The eyes feel tired.
• Astigmatism: This is a slightly different condition. Because the eye doesn't focus light properly, you may see things both near and far as slightly distorted, stretched, or blurry. One symptom of this is the appearance of streaks around headlights when driving at night.
• Presbyopia: This is not a disease. It is a natural condition that occurs when the lens of our eyes loses its flexibility after the age of 40. This also makes it difficult to see things that are close up, such as looking at a newspaper or tying a string.

There are several types of visual acuity tests.

We all know the chart with the letters, but there are actually several ways to do this test. It varies depending on the age and needs of the person.

This is exactly how the test works:

This is a very simple process. These are the steps that are usually followed:

1. Distance: You will be seated or made to stand in a chair about 20 feet away from where the chart is.

2. Closing one eye: Next, the doctor will tell you to close one eye with your hand or a small device that is provided with it. You can't just peek through your fingers, can you?

3. Reading the letters: Now you are asked to read the letters in order from the largest letter at the top of the chart, down.

4. Identifying the Limit: You keep reading until you reach a point where you can't read the letters clearly, and they become blurry.

5. Testing the other eye: When one eye is finished, open it, close the other eye, and repeat the test from the beginning.

If you already wear glasses or contact lenses, your doctor may perform this test twice.

• Without glasses: Measure your natural vision (uncorrected vision).
• Wearing glasses: Check how well your current glasses correct your vision.

What do the results say? Hindsight is 20/20...

When the test is over, your vision is reported in fractions. You've probably heard the story of "20/20 vision." They say that in movies, "His vision is perfect, 20/20."

The meaning of this is very simple.

20/20 vision means that something that someone with normal healthy eyes can see clearly at 20 feet away will be seen just as clearly at 20 feet away.

Imagine that your vision is 20/40. This means that to see clearly something that a normal person can see 40 feet away, you have to get up to 20 feet closer. This means that your distance vision is below average.

Also, if your vision is 20/15, it means that your vision is sharper than average. You can see clearly from 20 feet away what a normal person would see from 15 feet away.

But remember, most people don't have 20/20 vision without any correction. That's normal. After the test, your doctor will tell you what you need to do to correct your vision. In most cases, glasses or contact lenses will be prescribed.

The Visual Acuity Test is only one part of your complete eye exam. After this, the doctor will check your eye pressure, the nerves inside your eye, and many other things using other instruments (e.g., a slit lamp).