Visual Acuity: What is 20/40 Vision? – Eye Love Cares
What follows is everything you need to know about visual acuity, including what 20/40 vision means and much more. By having a full understanding of visual acuity, you can better determine the quality of your eyesight and know when it is necessary to take action in order to improve your vision.
A visual acuity score that is above average may help you function better in everyday life. Those who suffer from poor vision may be in need of glasses, contacts, or other forms of vision treatment to ensure the issue does not cause any serious complications on a daily basis.
What is Visual Acuity?
Visual acuity measures the clarity or sharpness of your vision. Visual acuity takes various factors into account, including your vision from twenty feet away compared to others, peripheral vision, etc. It is important to fully understand what visual acuity is, what your score means and what treatment options are available to those who suffer from poor visual acuity.
The main way visual acuity is tested is through an eye examination (see below), which measures a person’s vision and determines how their vision compares to others. The term “20/20 vision” is typically referred to as normal vision, and it simply means the individual can see at twenty feet what the average person can see at twenty feet.
The term visual acuity is most commonly referenced when discussing a visual acuity test – otherwise referred to as an eye examination. A visual acuity test utilizes what is known as a visual acuity chart, which consists of various lines of letters of different sizes.
A visual acuity test involves reading the letters from the visual acuity chart to determine the quality of the person’s vision. Rather than making the test results in a subjective grade by the vision examiner, the score is based on the results of others using a visual acuity scale. The visual acuity scale ranges from 20/10 to 20/200 and beyond. Any score that is above 20/200 is considered to be legally blind.
The bottom line is that visual acuity is the quality of your vision. The better your visual acuity score, the better your vision. If you do not know what your visual acuity score is, then you can schedule a visit with a vision expert – such as an optometrist – who can guide you through an eye examination and ensure you have what you need to see well each and every day.
What is 20 40 Vision?
One of the main questions people ask when it comes to visual acuity is: What is 20/40 vision? Perhaps you have recently received an eye examination and do not know what your score means or maybe you want to understand what a good vision score is before your visit to see an optometrist. In any regard, having a clear understanding of what 20/40 vision – and other vision scores – indicates is important.
To fully understand what 20/40 vision is, it is first important to have an understanding of how the eye examination is conducted. An eye examination – or a visual acuity test – involves the individual who is testing their eyesight standing 20 feet away from the visual acuity graph and reading the letters from the chart. The eye examiner guides the individual through a series of tests to see how well they can read the letters, and it involves reading with both eyes open, covering each eye, and it may include various other testing methods.
The result – for many – is where the confusion comes in. A vision score is graded on a scale, with 20/20 vision being normal. 20/20 vision indicates that the person can see at twenty feet what the average person can see at that distance – which is why it is considered the average of good vision.
A 20/40 vision score means the person being tested can see at twenty feet what the average person can see at forty feet, and it is considered below average eyesight. A person with 20/40 vision should consider contacts or glasses to improve their eyesight, if possible. If you have 20/40 visual acuity, you see twice as bad as the average person!
The first “20” in the vision score is constant, and the second number is different. The higher the second number the worse your eyesight, and the lower the second number – such as 20/10 vision – the better the eyesight.
The Role of Eye Examinations
Many become concerned when they are told they need an eye examination, and all too many believe the procedure to be useless and a waste of time. However, eye examinations play an important role in determining the quality of one’s eyesight and determining whether or not they need treatment for poor eyesight. Eye examinations can also detect diseases of the eyes and body which may not otherwise have been detected.
If an individual with 20/50 vision – or even as bad as 20/100 vision – receives an eye examination, they can then know exactly how bad their eyesight is and take the proper action to improve their vision. Many who suffer from poor vision get used to living with poor vision, and they may feel as if nothing is wrong. However, those with poor vision can significantly benefit from receiving treatment and improving their eyesight.
Additionally, eye examinations can work to identify eye complications that may not be easy to detect through other means – such as poor depth perception, bad peripheral vision and even retinal issues arising from macular degeneration or diabetes. By being able to catch any vision issues early, you can sometimes avoid the issue from worsening or lingering for longer than necessary.
Most who receive treatment for poor vision – whether it is through glasses, contacts or surgery – are surprised by how much their vision improves. No one should ever have to live with eyesight that makes it hard for them to function on a daily basis. Furthermore, everyone should have the opportunity to determine what their visual acuity score is to find out if they should seek treatment for any issues.
The bottom line is, comprehensive eye examinations are very important and while many are hesitant to receive an eye examination, they can work well to diagnose vision issues that may have gone unnoticed otherwise. They are relatively inexpensive and take minimal time to complete.
Related: Visual Acuity: What is 20/10 Vision?
When to Have an Eye Exam
Eye examinations can include more than a visual acuity test – although a vision test is one of the main purposes of an eye examination. However, eye exams can also include checking for any eye complications, such as a lazy eye, eye turns, cataracts, and retinal issues.
While it is important for everyone to receive an eye exam on a regular basis to ensure their vision is where it needs to be, there are other times when having an eye exam is necessary. The following are several reasons to consider having an eye exam done, although the reasons to receive a vision test are not limited to this list:
Children under three
It is important for children under the age of three to have an eye examination to determine if any eye issues or vision issues exist. As mentioned previously, eye examinations encompass more than testing the person’s vision, and they can also be conducted to determine if a young child suffers from any other forms of eye complications, such as a lazy eye. Be sure to ask your optometrist to conduct a thorough eye examination to determine if your child has any eye or vision concerns to know about. We recommend all children have their first eye exam between six months and one year of age.
Between the ages of three and five
It is important to check a child’s vision and overall eye health through an eye examination once or twice before the age of three, but it is also important for children to have their eyesight tested between the ages of three to five as well. Having an eye examination during this age range accomplishes several things, including checking to see if a previously diagnosed eye condition has improved or worsened and ensure no further complications have developed before the child starts kindergarten.
Once every two years during adolescence
Once a child starts the first grade, they should have their eyesight tested once every other year to ensure they do not develop any vision complications. The eyesight of a child is continuously developing, so it is important to monitor their development and schedule frequent eye examinations. In some cases, children at a younger age may need glasses or contacts in order to do well in school, and it is often hard for them to express a change in their vision. These children should have an exam once yearly.
Every one to two years as an adult
While it is important for individuals between the ages of seven to seventeen to receive frequent eye examinations, the rate of eye examinations can become less frequent after the age of 18 as eyesight is more consistent. Of course, seniors over the age of 50 may want to be more cautious and receive frequent eye exams, especially if they’ve been instructed to do so by their eye doctor.
Experience any concerning symptoms
Above are times when an eye exam may be important, but it is important to remember each individual has their own unique set of needs. While one person may only need an eye exam every two to five years, others who are at higher risk of eye complications should receive more frequent vision tests and eye exams. These instances may include monitoring for cataracts, glaucoma, macular degeneration, diabetic retinal issues, and hypertensive retinal issues.
Additionally, anytime symptoms of an eye or vision concern exist, it is important to visit a eye care professional for a complete eye exam. The earlier an eye complication is picked up, the easier it is to treat the issue.
Visual Acuity Test vs Vision Exam
Visual acuity tests are often compared to a vision exam. While they are similar, there are some differences to be mindful of when it comes to comparing the two. The main purpose of a visual acuity test is to measure the sharpness of one’s eyesight. In other words, visual acuity deals with the ability to see with clarity. A visual acuity test is almost exclusively concerned with one’s vision.
On the other hand, vision exams incorporate more aspects than vision, and it can be used to identify eye issues such as lazy eyes, cataracts and much more. While a visual acuity test can be used to determine if there is an issue with one’s eyesight and if vision treatment is needed, an eye exam can help dive further into exactly why someone may be suffering from poor vision.
In the event you visit an eye specialist, you are likely to receive a complete vision exam, which most likely includes a visual acuity test. If you are simply checking your general health, then a visual acuity test by itself may be all that is needed (this is often done at your child’s pediatrician, but a comprehensive exam is always recommended in addition). The exact tests an eye doctor may perform is dependent on the symptoms, complications and needs of each patient.
If a visual acuity test is performed and the results reveal a problem with one’s vision, then there are several treatment options available. The best form of treatment is dependent on the severity of the vision issue, and it is important to talk to your optometrist about the best treatment option when a vision issue exists.
The treatment that is most commonly recommended after a visual acuity test reveals a vision issue includes prescription glasses, contacts or laser eye surgery. For minor vision impairments – such as 20/40 vision – glasses or contacts are likely the most appropriate solution. For more severe issues – or for individuals who would prefer to not wear glasses or contacts – laser eye surgery may be the best solution.
A vision exam can include a visual acuity test, but it likely also includes several other forms of eye tests. Vision exams can reveal complications with one’s appearance, vision complications and many other issues. The treatment options for a vision exam that reveals an issue vary and is dependent on the exact issue of the individual.
Related: Visual Acuity: What is 20/20 Vision?
Types of Eye Exam Tests
The term ‘eye exam’ is a fairly broad term that can refer to a variety of different vision or eye tests. It can be helpful to have a full understanding of the different types of eye exam tests in order to determine which tests are most appropriate for you. If you can determine your symptoms, then choosing the right tests can be helpful in finding the cause.
Although there are many more types of exams your eye examiner may choose to utilize, here are five of the more popular eye tests that patients receive:
- Visual acuity test
- Perimetry test
- Eye muscle test
- Refraction assessment
- Color vision test
To further help you understand what exactly each test is, how it is performed and what it reveals, let’s go into more depth about each one.
Visual acuity test
A visual acuity test – which we have discussed in-depth in this article – is one of the more common forms of eye exams. The purpose of a visual acuity test is to determine the sharpness of one’s vision. The test is performed by having the person stand twenty feet away from the visual acuity graph and allowing them to read letters from the chart.
The score reveals how well the person can see compared against others. A 20/20 visual acuity score is average, and it means the person can see from twenty feet what the average person can also see from twenty feet, whereas a 20/40 vision score suggests the person can only see from twenty feet what the average person can see from forty.
A perimetry test shows how well a person can see from their peripheral view – which is defined as a vision that happens outside the point of fixation. Most understand peripheral vision as what they see to the side of where they are looking. Your peripheral vision can play a role in your ability to function on a daily basis.
There are several ways an eye examiner can determine the quality of one’s peripheral vision through a perimetry test, and it often includes having the individual pinpoint when they see a certain object to the side of where their eyes are focused.
Eye muscle test
An eye muscle test is one of the easiest eye exams to perform. It tests the strength of one’s eye and its ability to react in certain ways. There are several different ways to perform an eye muscle test, and the most common tests include having the individual follow an object while the examiner tracks their eye movement.
An eye with weak muscles may exhibit poor control as the person tries to keep their eyesight focused on the object that is moving, and it can suggest an eye complication exists and needs to be addressed.
A refraction assessment is often performed on individuals who have a vision problem and choose glasses or contacts as a way to improve their vision. A refraction assessment tests how well your eyes pick up light. This helps an optometrist determine the exact prescription the patient needs for their glasses and contact lenses.
The most common form of refraction assessment is performed by using a phoropter and sometimes retinoscopy, which measure the refractive error of the eye. Eye professionals can also utilize computerized technology in various ways to diagnose the severity of the refractive error as well.
Color vision test
A color vision test can be used when an individual is suspected to have poor color vision. There are several different methods an eye professional can utilize to determine if a person has a color vision issue, and the most common form of color vision test is a multicolor dot-vision test.
The dot-vision test can reveal if the person has any color deficiency as it can be difficult to pass the test when seeing certain colors is difficult. There are several treatment options available to those with color vision issues in order to help them deal with the complication on a daily basis.
Keep in mind that these tests only encompass the beginning of a comprehensive eye exam. Your eye doctor may choose to then dilate your eyes, check your eye pressure, and examine the front and back surfaces of your eyes.
Related: Visual Acuity: What is 20/15 Vision?
How to Avoid Vision Problems
There are some eye complications that are simply unavoidable, and it can be difficult to prevent eye complications in certain scenarios. However, the better you care for your eyes the better chance you have to avoid any serious complications from developing down the road.
While most do not think about their eye and vision health on a daily basis, making a conscious and concerted effort to practice good vision and eye care regularly is always a good idea. The following are several ways to ensure good eye health and vision and avoid developing eye complications as you grow older:
- Eat more fruits and vegetables
- Keep your eyes clean (we recommend using Heyedrate Lid and Lash Cleanser)
- Keep your contacts/glasses clean
- Avoid smoking and tobacco products
- Take breaks to avoid eye strain (and try Blue Light Blocking Glasses)
- Wear your glasses as directed
- Avoid too much sun exposure (purchase Polarized Sunglasses!)
- Know your family’s eye history
- Maintain good overall health
One of the easiest ways to practice good eye care and lower the chance of developing eye complications as you grow older is to simply eat more fruits and vegetables, which contain nutrients that promote good vision and help reduce the possibility of poor vision as you grow older.
Additionally, it is important to always keep your eyes clean, particularly the areas around your eye. When your eyelashes, eye glands, etc. are exposed to oil, sweat and dirt, then this can get into your eye and affect your overall eye health and vision over an extended period of time. Click here to purchase the Heyedrate Lid and Lash Cleanser. Also, dirty contacts or even glasses can cause eye irritation as well and lead to poor vision.
There are also studies that suggest smoking can lead to poor eyesight as well. It is important to limit your smoking when trying to keep your eyes healthy and maintain good vision. While quitting can be difficult for many, giving up cigarettes is often a necessary step to ensuring good vision long-term.
Eye strain has become more and more prevalent over the past decade. From sitting at the computer for long hours of the day to driving eight hours a day for work, to staring at your phone before bedtime, eye strain can cause severe eye discomfort and lead to future eye complications. Make sure to click here to get a pair of blue light blocking glasses to prevent eyestrain.
While eye strain may seem unavoidable – especially to those who work a desk job and sit in front of a computer for the majority of the day – simply taking a five-minute break when your eyes become tired and dry is a great way to avoid any long-term complications. Additionally, using eye drops to keep your eyes lubricated can help prevent eye strain and subsequent vision issues as well.
Glasses can be a great way to improve your vision when your visual acuity score is less than ideal, but it is important to wear your glasses as directed. Otherwise, you run the risk of constantly straining your eyes and affecting your vision in a negative manner more than necessary. For example, if your eye doctor suggests you wear your glasses anytime you are required to focus your vision, then be sure to not skip out and remove them when watching a movie or reading a book.
Another issue that can lead to poor vision over an extended period of time is sun exposure. While going outside without sunglasses every once in a while is not the end of the world, constantly working outdoors without eye protection can lead to dry eyes and eventually cause vision issues. Be sure to avoid too much sun exposure by wearing sunglasses, using sunscreen and limiting time spent outside when necessary. Click here to purchase a new pair of polarized sunglasses.
It is also important to know your family’s eye history when attempting to protect your vision long-term. The fact of the matter is some people are more at risk of suffering from poor vision than others and knowing if you are at a higher risk can help you prepare for any complications that may develop along the way. Be sure to consider the eye health of your relatives and talk to a professional about your chances of developing a vision issue or eye complication.
Lastly, be sure to do your best to stay in good health overall as doing so can lower the chance of developing eye complications. There are certain conditions that increase the chance of eye issues – including diabetes, high blood pressure and high cholesterol.
The Bottom Line
Visual acuity deals with the sharpness of your vision and the better your vision score the better you are able to see each day. While 20/40 vision may be a cause for concern and glasses or contacts may need to be considered, a more generous vision score – such as 20/20 or 20/10 vision – suggests you have no issues with your ability to see each and every day.