Question

When using a Snellen alphabet chart, the nurse records the client's vision as 20/40. What does this evaluation determine for the client?

Answer 1

A visual acuity measurement of 20/40 using a Snellen chart indicates below average vision compared to normal vision.

Step-by-step explanation:

When using a Snellen alphabet chart, a vision measurement of 20/40 would indicate that the client's visual acuity is below average compared to normal vision. The first number represents the distance at which the chart is being viewed (20 feet), and the second number represents the distance at which a person with normal acuity could see the same line of letters (40 feet). Therefore, a person with 20/40 vision can only see at 20 feet what a person with normal vision can see at 40 feet. In other words, the client's vision is half as sharp or clear as normal.

Answer 2

A Snellen chart measurement of 20/40 indicates that what a person with standard vision can see clearly at 40 feet, the client can see at only 20 feet, meaning their visual acuity is lower than normal.

Step-by-step explanation:

When a nurse records a client's vision as 20/40 using a Snellen chart, it signifies that the smallest line of letters that the client can read at 20 feet could be read by a person with normal vision from 40 feet away. This means the client has lower than normal visual acuity. In the context of the Snellen chart, the '20' represents the testing distance in feet between the client and the chart, and the '40' indicates the distance at which a person with normal vision can read the same line of letters.

Visual acuity is a measure of the clarity or sharpness of one's vision. A Snellen chart displays a progression of letter sizes, and while testing, the patient is asked to read the lines from a set distance, typically 20 feet. If a person has 20/20 vision, they can see at 20 feet what a person with normal vision is expected to see at the same distance, which is considered to be normal eye sight. If the visual acuity measurement is worse than 20/20, such as 20/40, it implies that their vision is not as sharp as the 'standard' normal vision.