Yes, it might be a good idea to do it specially if the SP tells you that he/she is having problems with vision.
Scoring of the Snellen chart in USA is determined by 20 feet not by 6 meters as everywhere else in the world.
The Snellen chart is composed of different rows of block letters that you have to ask the patient to read via each eye separately.
If the SP was maximally able to see the standard 8th row then this is the normal which is called 20/20. The row above it we call it 20/25 which means that the SP was only able to see the row at a distance of 20 feet while a normal person can see it at a distance of 25 feet.
The following image from Wikimedia Commons helps you understand more
This Snellen chart will be available in the standard examination rooms of all the SP encounters. However, please note that the side columns that mention the row number and visual acuity is shown here for educational purposes and may not necessarily be there during the exam.
