What Does 20/20 Vision Really Mean?
What does 20/20 vision really mean? To get a good grasp on this concept, we need to look at where the term comes from, what it measures, and what types of things your vision can be measured for overall.
Let’s uncover this term and learn more about your vision. And remember, if you need to see an optometrist to get your vision tested, make an appointment with PineCone Vision Center today!
Origins Of 20/20 Vision
The term “20/20” and other fractions measuring visual acuity are called Snellen fractions, named after Herman Snellen, a Dutch ophthalmologist who worked as a professor and director of eye disease research.
While other vision acuity testing charts had existed before (since 1835), Snellen standardized the chart to what you see today in 1862, with the large “E” at the top, and progressively smaller letters down the chart in a uniform fashion. Even the font used was custom designed by Snellen.
The big “E” at the top of the chart corresponds to 20/200 visual acuity, meaning if this is the only letter you can read, you can see things at only 20 feet away which normal people could see from as far as 200 feet away. If this is the only letter you can read, you are considered legally blind.
On most Snellen charts, the smallest letters correspond to 20/10 visual acuity, which means your vision is twice as sharp as that of a person with 20/20 vision.
Types Of Vision Measurement
Visual acuity (20/20, 20/10, etc.) isn’t the only way to measure your eyesight. Visual acuity only indicates the sharpness or clarity of your vision at a distance. Other vision skills it’s important to measure include peripheral or side vision, eye coordination, depth perception, focusing ability, color vision, contrasting vision and more.
An inability to bring objects nearby into focus can be caused by hyperopia (farsightedness) or presbyopia (loss of focusing ability). The opposite condition of being unable to focus on faraway objects may be caused by myopia (nearsightedness).
A comprehensive eye exam by an optometrist at PineCone Vision Center can diagnose what is affecting your ability to see well. In most cases we can prescribe glasses, contact lenses or a vision therapy program which will help improve your vision. If the reduced vision is due to an eye disease, you may be prescribed ocular medication or another treatment.
If you’re in need of an eye exam or any other eye health help, make an appointment today!
Levels Of Vision Acuity
20/20 – Normal vision. Required to read smaller print in the newspaper comfortably.
20/40 – Able to pass the driver's license test in all 50 states. Most printed material is at this level.
20/80 – Able to read a digital alarm clock at 10 feet. News headlines are this size.
20/200 – Legal blindness. Able to see “STOP sign” letters.
Posted: May 8, 2017