What is 20/20 Vision?
20/20 vision is a term used to describe good visual acuity (clarity) when measured from about 20 feet away. A person with 20/20 vision can see clearly without glasses or contact lenses at a distance of 20 feet.¹
Measuring visual acuity is typically the first step in an eye exam and the first step an eye doctor takes in understanding your overall eye health. While 20/20 vision does not mean someone has perfect vision, understanding visual acuity is important for eye doctors to determine the right treatment plan.
- 20/20 vision is the standard measure of visual acuity for someone with normal vision.
- Having 20/20 vision does not mean that you have perfect vision because it does not account for other visual impairments like depth perception, color vision and conditions that affect eye health.
- There are many reasons why vision can be less than 20/20 which is why annual comprehensive eye exams are important for overall eye health.
Understanding 20/20 Vision
While it does not mean you have perfect vision, 20/20 vision is a measure of the sharpness of your vision, which along with other visual tests, helps your eye doctor determine if you need corrective lenses.¹
The goal of corrective lenses (glasses or contact lenses) is to bring vision to 20/20. While it is not an indication of overall eye health, it is important for eye doctors (optometrists and ophthalmologists) to understand the sharpness of your vision in order to correct your eyesight.
Determining 20/20 Vision
During an eye exam, an eye doctor will measure your visual acuity with a chart called a Snellen eye chart.² He or she will have you typically sit or stand 20 feet away from the chart and read letters, which get progressively smaller as you go down each line of the chart.²
The results tell your eye doctor the sharpness of your vision, read as X/Y.²
- X is how many feet you are from the chart.
- Y is the distance in feet that the average person with normal eyesight can read the same line.
For example, if you have 20/40 vision (the lowest visual acuity allowed for driving in most states), it means that you must be as close as 20 feet from a point to see what a person with normal vision can see at 40 feet.²
20/15 vs 20/20 Vision
Someone with 20/15 vision can see better than the average person. They can see a point from 20 feet away when someone with normal vision needs to be 15 feet away to see the same point.²
20/15 vision is most frequent in younger populations with good eye health.²
What causes vision to be less than 20/20?
Numerous eye conditions can lead to poor vision that results in less than 20/20 vision. These are called refractive errors and include¹:
- Hyperopia (farsightedness): Being able to see well at distance but not up close
- Myopia (nearsightedness): Poor distance vision
- Astigmatism: Condition caused by an irregular curvature of the eye leading to blurred vision
Someone with 20/200 vision is considered legally blind. This means they can only see something from 20 feet away that the average person can see from 200 feet away.³