Many people refer to 20/20 vision as being perfect, and they sometimes joke that they want better than 20/20 vision, so they can see further. (Learn more) The measurement of 20/20 vision means something specific to eye specialists. Understanding what it means and the conditions it measures can help you determine your overall eye health. (Learn more)
Once you know if you have vision problems and what they are, you can determine if LASIK would be a good procedure. (Learn more) This laser-corrective outpatient procedure has helped millions of people get normal vision if they are nearsighted, farsighted, or have astigmatism. (Learn more)
However, one of the potential side effects of LASIK is overcorrection. Technically, this means your vision is better than 20/20 because it is sharper, but you may not feel like your vision is better due to associated eye strain. Instead, your eye doctor will work with you to decrease the sharpness of your vision, so you can see normally, or 20/20. (Learn more)
What Is 20/20 Vision?
The most common measurement of vision and associated problems involves measuring 20/20 vision. The number simply stands for the ability to see objects at a range of 20 feet; if you can see all objects clearly in your path within 20 feet, you have perfect vision. If you cannot see things far away, you are nearsighted (myopia), and being unable to see objects up close is farsightedness (hyperopia).
There are other important measures of visual acuity.
- Peripheral awareness or side vision
- Eye coordination
- Depth perception
- Ability to focus
- Color vision
These are measurements of different, but equally important, aspects of your overall ability to see the world around you while 20/20 vision measures specific issues with the cornea and the refraction of light to the retina to create a clear visual picture. If you have 20/30 vision, your vision is poorer than average because you need to be 20 feet from objects that people with average vision can see clearly at 30 feet. In most cities and states, you can get an unrestricted driver’s license if your uncorrected vision is 20/40 or better. People who wear corrective items like glasses or contacts and who still have 20/200 vision with these corrections are considered legally blind because they are unable to attain clear vision. Many children begin to lose their visual acuity around 8 or 9 years old.
Since 20/20 means measuring your ability so see clearly at a distance of 20 feet, is it possible to have better than 20/20 vision? In fact, 20/20 vision is not considered perfect; it’s just one measurement of visual acuity. You can have 20/20 vision but still suffer from other vision problems.
How Is Normal Vision Measured?
Although the term 20/20 is commonly used, it is a measurement predominantly used in the United States because the country is on the English system, measuring in inches, feet, and yards. In the United Kingdom, for example, normal vision is called 6/6 because visual acuity is measured within 6 meters.
Most people who have had an eye exam are familiar with the chart using letters, starting with a large E at the top, to measure visual acuity. This is called the Snellen Chart, named after Dutch eye doctor Herman Snellen who invented it in the 1860s. He also created a second chart, called the Tumbling E chart, which uses the large E in different orientations and sizes, as a method to help those who could not read. The doctor asks their patient to point their fingers in the direction that the “fingers” of the E are pointing on different lines. Using a standardized chart like the Snellen Charts allows people to go to any optometrist or oculist for a prescription and then go to any glasses maker for a set of glasses to correct their vision.
Standardization has helped optometrists, ophthalmologists, and other eye doctors understand different approaches to their patients’ vision problems and find ways to correct vision beyond prescribing glasses to adjust refraction problems. There are also many more steps in a common eye exam now than looking at a Snellen Chart.
- Discussing your history of vision problems
- Evaluating other aspects of your vision, such as eye pressure, muscle movements, and color vision
- Measuring how your pupils respond to light
- Keratometry to measure the curvature of the cornea
- Using a phoropter to determine if new refraction (a series of lenses) helps, hurts, or does not do anything
These tests and others will determine your overall eye health. If you have seen an optometrist to get prescriptions for corrective wear due to a refraction error, you may ask about LASIK to correct your vision. An in-depth eye exam will help your eye doctor understand if you are a good candidate for LASIK, if you would benefit more from a different refraction procedure, or if an underlying eye problem would prevent that surgery from benefitting your vision.
How LASIK Helps Normal Vision
People who have a refraction error in their vision experience problems focusing due to issues with the shape of their cornea in their eye, which then refracts light in a way that the brain cannot interpret the signals well through the optic nerve. Refraction errors include myopia (nearsightedness), hyperopia (farsightedness), astigmatism (change to the shape of the eye), and presbyopia (farsightedness specifically due to aging). One of the many procedures that can fix these refraction errors and help people live without glasses or contact lenses is LASIK, although there are many other surgeries that are not as well known.
Typically, LASIK advertisements state that the procedure will correct your vision, so you can see 20/20. Only about 35 percent of the world’s adults have 20/20 vision without glasses, contact lenses, or corrective surgery. But what does that mean? Is it possible to have better than 20/20 vision? How is perfect, corrected vision measured?
What Can LASIK Do to Improve Your Vision? Can You Get Better Than 20/20?
Since LASIK is a recognizable name for a refractive surgery, one of the simplest to perform, and one of the most useful with good long-term results, this is most likely the procedure you will be referred to if you ask about vision-correcting surgical procedures. Between 90 and 95 percent of laser vision correction is done with the LASIK procedure.
Although the goal of LASIK is to get your vision up to normal, or 20/20, you may only have 20/40 vision. This is considered within a normal range. If you still need corrective wear after the procedure to modify your vision, either because of undercorrection or overcorrection, you may return at a later date for an adjustment.
Having vision that is clearer than 20/20 is not necessarily beneficial. If you have ever had glasses with too high a prescription in one lens, you may experience eye strain, headaches, disorientation, or other side effects from a different type of vision problem.
There are processes to managing overcorrections, which may take a little more time and a few more checkups than returning to a lower glasses prescription and possibly getting an enhancement with a second LASIK procedure. But rest assured that overcorrections can be managed if they occur.
The Goal of LASIK Is Clear Vision
When you ask your optometrist or ophthalmologist about LASIK, know that the goal is to get normal vision, which is defined as 20/20 when dealing with refraction errors like astigmatism or presbyopia. LASIK will not treat other issues that lead to vision problems, like health issues from diabetes, glaucoma, optic nerve damage, or other illnesses or injuries.
Make sure to get a full eye exam to know exactly how and why you struggle with vision issues, so you can know how to approach these problems with medical help. That medical help may include LASIK to get you back to normal 20/20 vision.
What Does 20/20 Vision Mean? (November 30, 2016). American Academy of Ophthalmology (AAO).
Visual Acuity: What Is 20/20 Vision? American Optometric Association (AOA).
Visual Acuity FAQs. American Optometric Association (AOA).
All About the Eye Chart. (November 30, 2016). American Academy of Ophthalmology (AAO).
Comprehensive Eye and Vision Examination. American Optometric Association (AOA).
Laser Surgery Can Improve Vision Problems. University of Rochester Medical Center.
Manage Overcorrected LASIK With CLAPIKS. (April 2001). Healio: Primary Care Optometry News.