Last updated on April 17th, 2017 at 02:19 am
If you have an eye examination and are told you have 20/20 vision, does this imply you have perfect vision? Is it possible to attain even much better than 20/20 vision? And what is “twenty-twenty” anyhow?
To answer these concerns, let’s take a better take a look at vision-related terminology to fully comprehend how eye doctors determine the quality of your vision.
Visual Acuity, Eyesight and Vision: What’s the Difference?
Visual acuity. This, actually, is the sharpness of your vision. Visual acuity is determined by your ability to identify letters or numbers on a standardized eye chart from a specific seeing distance.
Visual acuity is a fixed measurement, meaning you are sitting still during the testing and the letters or numbers you are viewing also are fixed.
Visual acuity also is evaluated under high contrast conditions — typically, the letters or numbers on the eye chart are black, and the background of the chart is white.
Although visual skill testing is very beneficial to figure out the relative clearness of your vision in standardized conditions, it isn’t really predictive of the quality of your vision in all circumstances. For example, it cannot anticipate how well you would see:
- Things that are comparable in brightness to their background
- Colored objects
- Moving objects
Three significant physical and neurological aspects identify visual skill:
- How precisely the cornea and lens of the eye focus light onto the retina
- The sensitivity of the nerves in the retina and vision centers in the brain
- The ability of the brain to analyze details received from the eyes
Only light that is focused on an extremely small and highly sensitive part of the main retina (called the macula) affects visual acuity measurements gotten during an eye examination.
Visual skill generally is measured with Snellen fractions (see “What is 20/20 Vision?” below).
Eyesight. The exact meaning of “vision” is hard to pin down. Depending on which dictionary or other resource you examine, it can mean “ability to see,” “the sense of seeing,” “vision,” “range of sight” or “view.” Frequently, the terms “vision” and “visual acuity” are used interchangeably.
Vision. This is a wider term than visual skill or vision. In addition to sharpness of sight or just a description of the capability to see, the term “vision” typically includes a wider range of visual abilities and abilities. These include contrast sensitivity, the capability to track moving things with smooth and precise eye movements, color vision, depth perception, focusing speed and precision, and more.
If this more inclusive (and precise) definition of “vision” is used, what many people call “20/20 vision” should truly be called “20/20 visual acuity.” Realistically, that most likely won’t occur. For better or even worse, the term “20/20 vision” is likely here to stay.
Also read: Eye Exam: Time, Preparation and Cost
What Is 20/20 Vision?
The term “20/20” and similar portions (such as 20/40, 20/60, and so on) are visual acuity measurements. They likewise are called Snellen portions, named after Herman Snellen, the Dutch ophthalmologist who developed this measurement system in 1862.
In the Snellen visual acuity system, the top variety of the Snellen portion is the viewing distance between the patient and the eye chart. In the United States, this range normally is 20 feet; in other countries, it is 6 meters.
At this screening distance, the size of the letters on one of the smaller lines near the bottom of the eye chart has been standardized to correspond to “normal” visual skill — this is the “20/20” line. If you can determine the letters on this line however none smaller, you have normal (20/20) visual acuity.
The increasingly bigger letter sizes on the lines on the Snellen chart above the 20/20 line represent even worse visual skill measurements (20/40, 20/60, and so on); the lines with smaller letters below the 20/20 line on the chart represent visual skill measurements that are even better than 20/20 vision (e.g., 20/15, 20/12, 20/10).
The single big “E” at the top of most Snellen eye charts corresponds to 20/200 visual acuity. If this is the smallest letter size you can discern with your best corrective lenses in front of your eyes, you are lawfully blind.
On many Snellen charts, the tiniest letters correspond to 20/10 visual skill. If you have 20/10 visual skill, your vision is twice as sharp as that of an individual with normal (20/20) vision.
Is It Possible to See Better Than 20/20?
Yes, it’s certainly possible to have sharper than 20/20 vision. In fact, the majority of people with young, healthy eyes can identifying a minimum of some of the letters on the 20/15 line and even smaller letters on the Snellen chart.
This might be due in part to much better printing methods offered today vs. those in the 19th century when Snellen was identifying the smallest letters an individual with normal vision must be able to discern. So a case might be made that “normal” visual skill today is an ability to determine letters that are a bit smaller sized than those on the 20/20 line of a standard Snellen eye chart.
Even if you see 20/20, you might feel your vision isn’t really as sharp as you’d like. There are solutions for this.
On the other hand, individuals are living longer today than they carried out in Snellen’s age. Normal aging changes in the eye, such as early cataracts, might justify thinking about rather bigger letters than those on the 20/20 line as being a sign of “normal” vision amongst grownups in their 60s or older.
No matter these considerations, let’s say your eye doctor says you have 20/20 vision (or, more properly, 20/20 visual acuity), and you desire sharper eyesight. What can you do?
If your 20/20 vision does not appear sharp enough, it could be that your eyes have higher-order aberrations (HOAs) that can not be corrected with routine spectacles or soft contact lenses. Your eye doctor can look for these aberrations with wavefront innovation that is readily available in some eye care practices.
If HOAs are triggered by small abnormalities in the shape of the front surface of your eyes, being fitted with gas permeable contact lenses (GP lenses) frequently can improve your visual acuity much better than glasses or soft contact lenses. This is because GP lenses are stiff and basically replace the eye’s irregular front surface area with a perfectly smooth, curved surface to focus light more accurately.
Another choice may be custom wavefront LASIK. This tailored laser vision correction surgery can offer vision that is equivalent to wearing stiff gas permeable contact lenses (which typically is sharper than the visual skill offered by glasses or soft contact lenses), without the trouble of the everyday contact lens care.
If you prefer to wear spectacles to correct your refractive errors, glasses with special high-definition lenses might offer you sharper vision than regular spectacles lenses.
What Is “Perfect” Vision?
It’s almost impossible to measure what “perfect” vision is. Besides, a more intriguing question would be, “Perfect for what?”
For example, if you are driving on a warm day, excellent Snellen visual acuity may be the primary consider your complete satisfaction with your vision. But your sweetheart, who has worse visual skill than yours, may be better with her vision in the same circumstances due to the fact that she is wearing polarized sunglasses with anti-reflective coating that improve contrast and block glare.
Or an athlete who has better than 20/20 vision may battle with his performance since he doesn’t have specific dynamic visual skills that enable him to respond to moving things as quickly as a teammate whose static visual skill isn’t really as sharp as his.
Where to obtain Expert Advice
The initial step to making the most of the clearness and comfort of your vision in all circumstances is to see a qualified eye doctor or eye doctor for a comprehensive eye examination and vision examination.
If you have an interest in learning if laser vision correction might hone your vision better than glasses or contacts, ask to be referred to an experienced LASIK cosmetic surgeon for an assessment.
If you wish to maximize your dynamic vision skills for sports and other activities, look for an eye doctor who is a sports vision expert and ask about sports vision training.
Lastly, if your child has 20/20 vision but is dealing with eye strain and other vision problems in school, seek the advice of an eye care supplier who focuses on children’s vision to have your child evaluated for possible learning-related vision issues.