We've all heard the term 20/20 vision. The phrase 20/20 is used as a figure of speech in everyday conversation as well. But if your eye doctor tells you your vision is 20/20, will you know what that means?

Behold the Snellen chart

Visual acuity is most often measured using a Snellen chart. This is the familiar chart using letters of progressively smaller size you see in every eye doctor's office.

In the United States, the patient stands 20 feet away from the eye chart for their examination. Not every doctor's office is large enough to accommodate this, so the chart may be placed behind you, using mirrors to project it on the wall and to simulate the proper distance. Your eye doctor will ask you to read out loud the smallest row of letters you can see.

If you can read the chart from this distance, you can see what a "normal" human being should be able to see from that same point. (Let's remember "normal" is a relative term.) 20/20 vision is considered normal.

Does 20/20 vision mean I have perfect eyesight?

Unfortunately, no it does not. 20/20 simply indicates the clarity of your distance vision. Obviously having good distance sight is vital, but there are other aspects of your visual ability, such as peripheral vision, depth perception, color vision, and focusing ability that are also important to your over-all visual strength.

How's your visual acuity?

If your doctor tells your vision is 20/40, this means you are able to see what a normal person can when they are 40 feet away if you are standing 20 feet from the Snellen chart. In order to obtain a driver's license, your corrected visual acuity (meaning when you are wearing glasses or contact lenses) must be at least 20/40. This is also the level of acuity needed to read most printed material. Anyone with 20/200 vision or less is considered legally blind in the United States.

It's possible for your visual acuity to be better than the norm as well. If you have 20/10 vision, you can make out at 20 feet what the average person can only see at 10 feet.

The Eyes Have It

Good eye health is so much more than your distance sight alone. A comprehensive eye examination is the best way to ensure all your bases are covered. Simple preventative measures, such as regular checks for glaucoma, are vital to maintaining healthy eyes. Be sure to see your eye doctor regularly.

For more information, contact a business such as Las Vegas Family Eye Care.