A normal eyesight test primarily assesses visual acuity, which is the sharpness of your vision at various distances. The widely accepted standard for normal vision is 20/20 (6/6).
What is Visual Acuity?
Visual acuity is a measure of how clearly you can see details. It's typically tested using a chart placed at a standard distance. The most common chart is the Snellen chart, featuring rows of letters that decrease in size.
Understanding the Numbers: 20/20, 6/6, and Beyond
The numbers used to describe visual acuity, such as 20/20 or 6/6, represent a comparison:
- 20/20 Vision (or 6/6): This means that you can read a line on the eye chart from 20 feet (6 meters) away that a person with normal vision is expected to read from the same distance. 20/20 (6/6) is considered normal visual acuity.
- Other Measures (e.g., 20/40 or 6/12): Numbers like 20/40 indicate reduced visual acuity. According to the reference, 20/40 (6/12) indicates that the line you correctly read at 20 feet (6 meters) away can be read by a person with normal vision from 40 feet (12 meters) away. This means your vision is less sharp than the 20/20 standard.
How the Test Works
During a standard eyesight test (often called a visual acuity test):
- You stand or sit at a specific distance from the eye chart.
- You cover one eye while reading the smallest line of letters you can see with the other eye.
- This process is repeated for the other eye.
- Sometimes, both eyes are tested together.
The smallest line you can read clearly determines your visual acuity score for each eye.
What "Normal" Means in This Context
While 20/20 (6/6) is considered normal and indicates excellent visual acuity at a distance, an eyesight test often includes other assessments, such as:
- Refraction Test: To determine if glasses or contacts are needed to correct blurry vision.
- Eye Health Examination: Checking for signs of eye diseases.
However, when people refer to a "normal eyesight test" result based on the number, they are typically talking about achieving 20/20 vision.
Summary of Visual Acuity Scores
Understanding the common scores helps interpret the results:
| Score | Meaning | Interpretation |
|---|---|---|
| 20/20 | Read at 20 ft what a normal person reads at 20 ft. (Equiv. 6/6) | Normal Vision |
| 20/40 | Read at 20 ft what a normal person reads at 40 ft. (Equiv. 6/12) | Below Normal Acuity |
| 20/100 | Read at 20 ft what a normal person reads at 100 ft. (Equiv. 6/30) | Significantly Reduced |
Achieving 20/20 (6/6) is considered normal and is the benchmark for clear distance vision in an eyesight test.
