It’s easy to think that having 20/20 vision means having “perfect” eyesight. However, this term is merely a measure of your visual acuity. It’s very possible to have 20/20 vision and still contend with other eyesight problems.
Measuring Visual Acuity
If you have ever been asked to stand in front of an eye chart, cover one eye, and read the smallest line of letters you can, you have had a visual acuity test. Eye charts, also known as Snellen charts, are named for Dutch ophthalmologist Herman Snellen, who developed this technique for measuring visual acuity in 1862. Also, the fractions representing visual acuity, including 20/20, are known as Snellen fractions.
Variations on 20/20 Vision
Having 20/20 vision means you can see what a person with normal visual acuity can see from 20 feet away. Many people strive for 20/20 vision, but this is not the best vision you can have. Of course, visual acuity can also be worse than 20/20. Here are some examples:
- 20/15 vision is better than 20/20. It means you can see clearly at 20 feet what someone with normal visual acuity can only see from 15 feet back.
- 20/40 vision is worse than 20/20. It means you must stand within 20 feet to see what someone with normal vision can discern from 40 feet away. This is the visual acuity required to pass a driver’s license test.
- 20/200 vision is considered legally blind. With this poor visual acuity, everything except the large letter E at the top of a Snellen chart appears blurry from 20 feet away.
Differences in Visual Acuity by Distance
Reading letters off a Snellen chart is effective for detecting myopia (nearsightedness). This is when far-away objects appear blurry. But the opposite problem, known as hyperopia (farsightedness), can also occur. This is when up-close objects appear blurry. Presbyopia is similar, but this condition sets in gradually with age, eventually requiring reading glasses. Other conditions, including astigmatism and eye disease, can also affect visual clarity.
Other Important Vision Skills
Consider these other vision skills besides visual acuity that are necessary for good eyesight:
- Depth perception
- Peripheral awareness
- Eye coordination
- Focusing ability
- Color vision
- Ability to track moving objects
- Ability to discern objects similar in brightness to their background
The Importance of Eye Exams
If you have trouble focusing on objects up close or far away, an optometrist can prescribe corrective glasses or contact lenses to bring the world into focus. Even if you have 20/20 vision, regular eye exams are still important to assess your eye health, monitor changes in vision, and detect and diagnose eye diseases before symptoms set in.
Arvada Vision & Eye Clinic offers routine eye exams and other optical care to help you see as clearly as possible. We are committed to ensuring your comfort and satisfaction while in our office. To enjoy tailored treatments that suit your lifestyle and vision needs, please request an appointment with us today.