How to test visual acuity with a Snellen chart
Other platforms explain it with text and video. In VMS you practice it on the patient.
Visual acuity is the vital sign of the eye. Test it in every eye complaint.
What you need
- Snellen chart
- Occluder or card
- Pinhole
Step by step
Set up
Chart at 20 feet (6 meters), good light. [1]
One eye at a time
Cover the other eye without pressing. [1]
With glasses
Test with distance glasses if they use them. [1]
Read down
Smallest line with most letters correct. [1]
Pinhole
If worse than 20/20, repeat through a pinhole: improvement suggests a glasses problem. [1]
Record
For example 20/40 right eye with glasses. If no line, count fingers, hand motion or light. [1]
Common errors
- Pressing on the covered eye.
- Testing without glasses.
- Not using the pinhole.
Practice it in VMS
In VMS you do this on the patient, not on paper: every step goes on the checklist with a score, and in Teach mode Blocky tells you what comes next.
VMS cases that train this skill
Sources
- Open RN, Nursing Skills 2e (Chippewa Valley Technical College) (CC BY 4.0)
- OpenStax, Clinical Nursing Skills (CC BY 4.0)
Steps adapted from Open RN, Nursing Skills 2e (Chippewa Valley Technical College) and OpenStax, Clinical Nursing Skills, licensed under CC BY 4.0. VMS is not affiliated with these organizations. Updated: 2026-10-11.