Certified Paraoptometric Practice Test

How is a Snellen chart used in eye examinations?

1. To test a patient's visual acuity at various distances

2. To measure the curvature of the cornea

3. To assess the patient's eye muscle strength

4. To screen for color blindness

The correct answer is: To test a patient's visual acuity at various distances

A Snellen chart is specifically designed to measure visual acuity, which is the clarity or sharpness of vision. During an eye examination, patients read letters from the chart placed at a standardized distance, typically 20 feet. The results indicate how well a person can see compared to a standard vision level, usually represented as a fraction (e.g., 20/20 vision means the patient can see at 20 feet what a person with normal vision can see at 20 feet). This method is essential for determining how vision may be affected by underlying eye conditions or abnormalities. Other uses and assessments that involve eye examinations, such as measuring corneal curvature or assessing eye muscle strength, involve different instruments and procedures that are not related to the visual acuity testing offered by the Snellen chart. Additionally, screening for color blindness also utilizes different tests aimed at assessing color perception, rather than visual acuity. Thus, the primary and correct function of the Snellen chart is to evaluate a patient's visual acuity at various distances.