Ever question what 20/20 vision really means? The term 20/20 eyesight expresses normal visual acuity or clarity of vision. In other words someone with such eyesight will be able to see an object clearly from 20 feet away which is considered normal to see clearly at that distance.
In cases of individuals that cannot see at 20 feet away, the number is determined according to where they begin to see clearly in relation to what is normally expected. As an example, if your vision is 20/100 that means that you have to be at a distance of 20 feet to see what a person with normal vision can see at 100 feet away.
Someone with 20/200 eyesight is considered legally blind however, they can often achieve much improved vision through glasses or contacts or by having LASIK if they qualify.
An average eye screening is performed with the use of a vision chart usually the classic Snellen eye chart designed by Dutch eye doctor, Herman Snellen in the 1860's. While there are many versions, the chart generally has 11 lines of capital letters which get smaller in size as one looks downward. The top of the chart usually shows the capital letter - ''E'' with letters being added subsequently as you move down the chart. During the eye exam, the optometrist will examine which is the smallest line of letters you can make out. Every row is given a distance, with the 20/20 row typically being ascribed the eighth row. For young children, illiterate or handicapped persons who can not read or vocalize letters, a different version of the chart is used called the ''Tumbling E''. Similar to the traditional Snellen chart, this version is composed of only the uppercase E in different directions. The eye doctor tells the person being tested to mimic which direction the ''fingers'' of the E are facing: right, left up or down. Both charts should be placed 20 feet away from the patient's eyes.
Despite common conception, 20/20 vision doesn't show an individual has perfect eyesight but merely that their distance vision is normal. Total eyesight includes many other important skills such as side or peripheral vision, perception of depth, color vision, near vision and focusing and coordination between the eyes to name a few.
Although a vision screening with a Snellen chart will often determine whether you require a visual aid to see far away it will not give the optometrist a complete understanding of your complete eye health. It's recommended that you still book a yearly comprehensive eye exam which can identify any more serious diseases. Call our office now to book a Rye Brook, NY eye test.