What Does 20/20 Vision Actually Mean?

You've probably heard the phrase "20/20 vision" used to refer to normal eyesight. But what does this measurement actually mean? Understanding your visual acuity score can help you determine if you need corrective eyewear or treatment for vision problems. Our team at Karns Vision Center in Knoxville would like to take a closer look at 20/20 vision.

How Is Visual Acuity Measured?

Visual acuity is a measurement of how clearly you can see. It’s determined by having you read letters on an eye chart from a set distance, usually 20 feet. The first number refers to your distance from the chart. The second number represents the distance at which a person with "normal" acuity could read the same line you just read.

So, 20/20 means you can read at 20 feet what a person with typical vision can read from 20 feet away. Conversely, 20/40 means you have to stand 20 feet from the chart to read what someone with regular vision can read from 40 feet.

What Is Considered Normal Visual Acuity?

20/20 vision is considered normal acuity, but some variation is still within the typical range:

•  20/15 vision is better than average
• 20/20 vision is normal
• 20/25 vision is barely below normal
• 20/40 vision indicates mild nearsightedness
• 20/200 means you cannot read the big E at the top from 20 feet away

As your visual acuity score increases, your vision generally worsens. Anything below 20/40 usually requires vision correction, such as glasses or contacts, to see clearly, especially for activities like driving.

What Affects Visual Acuity?

Several eye conditions can decrease visual sharpness and cause vision to fall below 20/20, including:

• Nearsightedness: Objects farther away appear blurry
• Farsightedness: Nearby objects are difficult to focus on
• Astigmatism: Blurred vision due to an irregular eye shape
• Presbyopia: Difficulty focusing on close objects due to aging
• Cataracts: Cloudy lenses obstruct clear vision

Regular comprehensive eye exams are essential for detecting these issues before significant vision loss occurs.

Keeping Your Eyes Healthy

To maintain good vision and eye health:

• Get an annual eye exam to check for problems
• Update your eyeglasses prescription regularly
• Wear sunglasses to prevent UV damage
• Follow proper contact lens hygiene
• Eat foods rich in nutrients that protect your eyes
• Quit smoking, as it raises the risk of glaucoma and cataracts

Reach Out to Our Optometrist Near You

At Karns Vision Center in Knoxville, TN, our optometry professionals provide complete vision care and eye exams to help you achieve and preserve clear sight. Contact us to schedule your eye exam today.