What it means
The standard distance visual acuityVIZH-oo-ul uh-KYOO-ih-teeHow clearly and sharply a person can see.visu sightacu sharpFull entry test. The person stands 20 feet (about 6 meters) away and reads the smallest line they can, one eye at a time. The result is written as a fraction: 20/20 is normal, and 20/40 means the person sees at 20 feet what a person with normal vision sees at 40 feet. Charts with pictures or the letter E pointing different ways are used for young children. It is named after Herman Snellen, the Dutch eye doctor who made it in 1862.
For the nurse
Test with glasses or contact lenses on if the client wears them, and chart that you did.
At a glance
| Also written | Snellen's chart, Snellen eye chart, Snellen test |
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Related terms
visual acuity
How clearly and sharply a person can see.