Basic Terminology

Eye Know

The terminology at your eye doctor’s office can sometimes be hard to understand. This goes for language like 20/20 vision, shortsighted, farsighted. All of these are common expressions used in your eye doctor’s office, but do you know what they actually mean?


Most people have the common misconception that 20/20 vision equals “perfect” vision, which isn’t necessarily the case.

20/20 vision is generally measured by something called a Snellen chart. The Snellen chart displays lines of letters that progressively get smaller in size, which in turn measures how far a person can see.

During an eye exam, your doctor will ask you to find the smallest line of letters that you can read and ask you to recite it out loud. If you are able to see all of the lines and read the letters with no apparent issue, this means that you have 20/20 vision, which is actually “normal” vision.

So while 20/20 doesn’t mean perfect vision, it does mean that you can read at twenty feet a letter that most human beings should be able to read at this distance.

It is important to know that eye charts are utilized for the sake of measuring visual acuity only. They do not determine, or measure, your peripheral vision, depth perception or anything else related to the health of your eyes such as eye fluid pressure or glaucoma, etc. Eye chart testing is just one part of a complete eye exam, which should be taken every one or two years to ensure that your eyes are healthy.

Shortsighted or Nearsighted

In order for you to see clearly, the light coming into your eye needs to be focused on your retina, which is located in the back of your eye.

If you’re shortsighted, this means that your eyeball is longer than normal, so the light focuses in the front of the retina and you are not able to see things clearly if you are far away from them. An example of this is when you are watching television or trying to read the board in your classroom and the words and/or picture blurs.

This is also known as myopia.

Farsighted or Longsighted

Now, if you are farsighted, this means the exact opposite: that your eyeball is shorter than average, which means that the light focuses behind the retina. In turn, this means that you have to overcompensate to focus, specifically on things that you would normally do close up, such as reading and working on the computer.

This is known as hyperopia.

The Big Picture

Both of these conditions are known to have a strong genetic component, but there are significant environmental factors that may have a strong influence on the development of being shortsighted or farsighted. For example, young people who spend a significant amount of time reading or working on the computer are known to develop short-sightedness in a more rapid state than others in the same age range.

That said; did you know that children as young as six months are able to visit the eye doctor for routine eye exams? It’s also a good idea to come in for additional eye exams at the age of three, as well as just before kindergarten. Prevention is the key to avoiding these conditions.