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20-40 Vision: What Does It Mean?

If you have a score of 20/40, it means that your vision is less than perfect but still pretty good. 

The familiar term is 20/20, which indicates that your vision is what people can normally see from 20 feet away. With 20/40, you can see at 20 feet what an average person sees at 40 feet.

In many states, you can drive with this vision without mandated eyewear. However, you may find that seeing certain things, such as flight information at the airport, is a little tough.

According to the University of Iowa Hospitals & Clinics, only about 35 percent of adults have 20/20 vision without corrective eyewear or surgery. With corrective glasses, contacts, or surgery, about 75 percent of adults have 20/20 visual acuity, leaving 25 percent of the population unable to see very clearly.

Only a doctor can accurately measure your ability to see clearly, called visual acuity

What Does 20-40 Vision mean?

When you get a prescription for 20/40 vision, it means that you must be 20 feet from things that people with 20/20 vision can see clearly at 40 feet. 

In other words, your doctor may prescribe eyewear, such as contacts or glasses, to correct your vision. Some people with 20/40 vision don’t opt for vision correction since they can often drive and perform other activities without corrective eyewear.

Visual Acuity 

Visual acuity is a term used to describe the sharpness or clarity of a person’s vision.

Visual acuity tests often include an eye exam and reading an eye chart. This is called a Snellen chart, and it has letters in different sizes on each line of the chart. 

Testing for visual acuity is relatively simple, and it is often done by a technician, optician, or optometrist. 

How Does Your Doctor Determine if You Have 20-40 Vision?

Your doctor will measure visual acuity with a classic eye exam. During the exam, your doctor will typically check each eye individually, as it is common for one eye to see more clearly than another. 

Covering up one eye at a time, you’ll call out the letters you can see on a line of the Snellen eye chart. The doctor or health care provider will place a correction lens in front of your eyes to determine which prescription is needed to help you see clearly.

You’ll go through these steps with one eye and then the other. When you’ve finished the test, your doctor will have the information to create an effective prescription.

What Else Determines How Good Someone’s Vision Is?

According to the American Optometric Association, vision skills include more than clarity of vision at a distance. 

One of the important aspects of vision is peripheral vision, which is seeing what is to the side of one’s visual field. Depth perception, eye coordination, ability to focus, and ability to distinguish colors all constitute one’s level of vision. 

Can Someone Have Better Than 20/20 Vision?

The term 20/20 vision is used to describe normal vision. According to the American Academy of Ophthalmology, 20/20 means that the person can see what a normal person can see from a distance of 20 feet away.

While 20/20 is often considered a “perfect” score for vision, it is possible to have vision that is better than this standard. Many children have eyesight that is better than 20/20, such as 20/10. This means they can see at 20 feet what the average person can see at 10 feet.

Tools to Sharpen Your Vision

There are various ways to improve your vision, such as through the use of corrective lenses like glasses or contacts, surgery, and lifestyle modifications. 

Glasses

Glasses are a good choice if you need occasional help with your vision. 

Glasses don’t require much effort or maintenance, and they are easy to integrate into your lifestyle. For instance, you may use glasses only while you drive or read.

Studies find that people who wear glasses are less likely to experience depression compared to those who do not wear glasses. This is likely because blurry vision can take a toll on one’s life.

Contact Lenses

Contacts can help you adjust your vision while maintaining a youthful appearance. Many people prefer contacts to glasses because they are easy to use and do not crack, fog up, or slide down your nose. Contacts support an active lifestyle since they don’t get in the way like glasses sometimes can.

If you are new to contacts, it may take a little while to get used to wearing them. You’ll need to get familiar with how to put them in and take them out as well as how to clean, store, and replace them. 

Surgery

To more permanently correct your vision, LASIK and other surgeries may be options. 

LASIK reshapes the cornea so light refracts as it should, and images appear sharper. Many people enjoy the freedom they gain after LASIK since they no longer have to rely on glasses or contacts. 

Lifestyle Modifications

According to John Hopkins Medicine, it is possible to support good health and reduce the impact of natural aging on eyesight. 

Here are some recommendations for ways to best preserve your vision:

Stop Smoking

Smoking is a leading cause of age-related macular degeneration (ARMD). An Australian study estimated that one in five cases of ARMD could be linked to smoking. 

Smoking also causes cellular change, vascular constriction, and oxidative stress.

Wear UV Protection

Put on your sunglasses. Protecting your eyes from UV light can protect your vision and reduce your risk of developing cataracts.

Enjoy Being Active

According to the American Academy of Ophthalmology, exercise may hold the key to staving off eye disease. Physical activity can help your eyes stay healthy. It’s good for your general health as well.

Maintain a Healthy Weight

Studies show that being overweight puts strain on your heart, blood pressure, blood sugar levels, and your eyes. Maintaining a healthy weight is a way to protect your eyesight and your overall health.

20/40 Vision FAQs

Does someone with 20-40 vision need glasses?

Many people have good visual acuity with 20/40 vision and don’t wear glasses. But this is an individual choice. 

According to the Centre for Vision in the Developing World, a 20/40 score can make some things difficult, such as reading menus on a blackboard, deciphering flight details at the airport, or watching movies with subtitles. It may be challenging to read the fine print of a recipe or instruction manual. 

If this is the case for you, you may want to invest in some corrective lenses. Your corrective eyewear would give you 20/20 vision.

Can a person with 20-40 vision drive?

In many states, you can drive with uncorrected 20/40 vision. You are still considered a safe driver.

Check with your local Department of Motor Vehicles to find out the regulations and guidelines in your state.

What does it mean if you have 20-40 vision?

If you have 20-40 vision, it means that you can see at 20 feet what a person with normal vision could see at 40 feet. This means that your vision is worse than what is considered to be average, or normal, eyesight. 

It doesn’t necessarily mean that your vision is bad — just that it is poorer than 20/20. Oftentimes, people with 20/40 vision don’t use corrective eyewear.

References

  1. What Is 20/20 Vision? (May 2018). University of Iowa Hospitals & Clinics. 

  2. Visual Acuity. American Optometric Association.

  3. 20/20 Vision: What It Means & Corrective Measures. (April 2022). Cleveland Clinic.

  4. All About the Eye Chart. (March 2022). American Academy of Ophthalmology.

  5. Can You Have Better than 20/20 Vision? (January 2020). Association of Schools and Colleges of Optometry.

  6. Best Way to Age-Proof Your Vision. John Hopkins Medicine.

  7. Eye Diseases. Tobacco in Australia. Cancer Council Victoria.

  8. Exercise May Stave Off Eye Disease, Study Finds. (October 2020). American Academy of Ophthalmology.

  9. Delivering Glasses to 2 Billion People Who Lack Access to Conventional Eye Care Services. (August 2016). Centre for Vision in the Developing World.

  10. Distance Visual Acuity of 20/40 or Worse Associated With Decreased Participation in Daily Activities. (May 2005). Investigative Ophthalmological & Visual Science.

  11. Differential Visual Acuity – A New Approach to Measuring Visual Acuity. (January–March 2020). Journal of Optometry.

Last Updated July 20, 2022

Note: This page should not serve as a substitute for professional medical advice from a doctor or specialist. Please review our about page for more information.