Distance Visual Acuity

A Snellen Chart assesses the client’s distant visual acuity.

Purpose:

Helps identify occupational limitations

Links occupational limitations to visual impairments

Helps to develop an intervention plan

Supplies Needed:

Snellen Chart

Eye Patches

Client’s Corrective Lens (if applicable)

How to administer:

1. Hang the Snellen chart on a plain wall 10 feet away from the client at eye level.

2. Once, the chart is in place, go and stand beside the client. Use a copy of the Snellen chart to follow along with them to check their performance.

3. Have the client cover one eye wearing their corrective lens if they have any.

4. Start at the top of the chart with the first line and have the client begin to read down through the lines saying each letter one at a time.

5. Watch for errors in recognition of letters. The client needs to read at least half of the letters in each line correctly to receive credit for that line. If the client reads less than half of the current line of letters correctly, you will go back to the previous line and record what they got correct. 

6. When documenting, record the smallest line the client read correctly with at least half of the letters read. You will also indicate whether their vison was corrected or uncorrected with lenses while reading the chart.  Ex. Va distance 20/30 -2 uncorrected.

7. Once the client completes the chart with the first eye, administer the Snellen Chart again with the other eye covered, and then finally with both eyes uncovered.

Things to look for in the client:

1. Accuracy

2. Observe for sequencing errors

3. Letter reversals

4. Reading right to left

5. Improvement with isolation of letters

Norms:

Normal Va: 20/20

PA Driving: 20/40

Participation in Daily Occupations: 20/50

Legally Blind: 20/200