Have you ever asked yourself what 20/20 eyesight really represents? 20/20 vision is a term to describe normal visual acuity or sharpness of vision. That is to say that someone with 20/20 visual acuity will be able to clearly see an object from 20 feet away that most individuals should be able to see from such a distance.
For those who don't have 20/20 vision, the number is designated based on where they begin to see clearly in relation to what is normally expected. For instance, if your acuity is 20/100 that means that you must be at a distance of 20 feet to see clearly what someone with normal visual acuity would be able to see at 100 feet away.
A person who is assessed with 20/200 vision is considered blind, legally but can often achieve much improved vision by wearing eyeglasses or contact lenses or by having laser eye surgery if they qualify.
An average vision test is done by using an eye chart most commonly the familiar Snellen eye chart designed by Dutch eye doctor, Herman Snellen in the mid-1800's. While today there are quite a few variations, the chart generally has eleven lines of capital letters which get progressively smaller as they move downward. The top of the chart usually shows the uppercase letter - ''E'' and gradually adds more letters on the lines as they get smaller. During the vision screening, the eye doctor will look for the line with the smallest lettering you can make out. Each line is given a distance, with the 20/20 row typically being assigned forth from the bottom. In instances in which the patient can't read, such as small children or disabled individuals, a different version of the chart is used called the ''Tumbling E''. At the same scale as the standard Snellen chart, this variation portrays only the uppercase letter E in different directions. The optometrist asks the patient to point to the right, left, top or bottom based on the direction the E is facing. Both charts must be positioned 20 feet away from the patient's eyes.
Even though 20/20 visual acuity does indicate that the person's sight for distances is normal, this metric alone doesn't imply that the individual has flawless vision. There are a number of other necessary abilities needed that contribute to your overall vision such as side or peripheral sight, depth perception, focus for near vision, color vision and eye coordination amongst others.
It's important to remember that even though an eye exam using an eye chart can establish if you require eyeglasses to see clearly at a distance it doesn't provide the optometrist a comprehensive picture of the overall health of your eyes and vision. It's recommended that you still book an annual comprehensive eye exam to screen for any more serious conditions. Call us today to schedule an eye exam in Ramsey, NJ.