You’ve no doubt heard of the term 20/20 vision before, and it’s likely to have been in reference to someone with extremely good eyesight. But what does it actually mean to have 20/20 vision? Let’s find out.
To understand what it is to have 20/20 vision, you first need to know more about visual acuity and how it is measured. You’ve almost certainly had this done before at your routine eye exams, even if you don’t realize it. That’s because visual acuity is measured using an eye chart called a Snellen chart. It gets its name from the ophthalmologist that invented it as a tool for measuring how clearly you can see.
Visual acuity refers to the clarity of your eyesight, and this is determined by measuring how well you can see from a specific distance. A Snellen chart contains a range of letters in different sizes, getting progressively smaller as you read down it. Your eye doctor will ask you to read the letters out to assess how accurately you can see them. This may not necessarily happen in order, and your eye doctor may also switch to alternative charts depending on how your visual acuity assessment goes.
Visual acuity is determined by several different factors, including:
If there are issues with any of the above, you may find that you can’t see clearly at all distances.
The 20/20 term is a fraction that is used to explain how clearly you can see at different distances. The first number refers to the distance between yourself and the eye chart, which is 20 feet. The second number explains the distance at which you can see a specific letter on the Snellen chart clearly.
For example, someone who has 20/100 vision can see from 20 feet what a person with normal visual acuity can see from 100 feet away. This would indicate that you have very poor vision. Although it is possible to have vision that is clearer than 20/20, it’s not at all common. The letters on the very bottom row of a Snellen chart represent 20/15 vision, and while you may potentially be able to identify some letters, it’s unlikely you’d get them all correct.
Only around 35% of adults have 20/20 vision without using glasses, contact lenses, or corrective surgery. However, when using prescription lenses, it’s possible to dramatically increase this number. You don’t have to have 20/20 vision to drive. The legal driving standard is 20/40, but this is with prescription lenses.
If you would like to find out more about what it means to have 20/20 vision, or to make an appointment for a visual acuity assessment, contact Advanced Eyecare Center at our office in Perry, Georgia. You can call (478) 412-4200 today to schedule an appointment.