Snellen Chart
An assessment tool used to evaluate distance visual acuity.
Assessment Preparation:
- Use tape measure to determine patient's distance from chart
- Chart is placed 10 feet in front of patient
- Chart is at patient's eye level (make chart removable)
- Place chart on 'plain' wall with no other distractions
- Patient wears corrective lenses (if applicable)
- Use index card (or similar object) to cover patient's eye
- Make Snellen Chart cheat sheet prior to assessment
Assessment Procedure:
- The OT will stand next to the patient with a copy of the Snellen Chart to verify if the patient is correct
- Patient covers one eye
- Patient begins reading the largest letter
- Patient will read each line of letters one at a time
- Test sequence is one eye (opposite eye covered), other eye (opposite eye covered), then both eyes
- Record smallest line read correctly with more than half of letters read
- Documentation example: "Va distance 20/40 - 2 uncorrected"
- Include whether or not the patient was wearing corrective lenses
What to Look For:
- Accuracy
- Observe for sequencing errors
- Letter reversals
- Reading left to right
- Improvement with isolation of letters
"Normal" Va = 20/20
Legally Blind = 20/200
Participation in daily occupations = 20/50
Va for driving is determined by state: PA requirement = 20/40 best corrected