Certified Medical Assistant (CMA) Baseline Practice Test

The Snellen chart is primarily used to measure visual acuity, which is the clarity or sharpness of vision. This chart displays letters of various sizes and is specifically designed to assess how well a person can see at a distance. During an eye exam, the patient is asked to identify the smallest letters they can see clearly from a standard distance, typically 20 feet. This allows healthcare providers to determine the individual's visual acuity, which can be critical for diagnosing vision problems and planning appropriate treatments.

The other options refer to different types of assessments. Audiometry measures hearing ability, which is unrelated to visual testing. Color vision tests assess a person's ability to distinguish different colors, not visual acuity. Contrast sensitivity tests evaluate how well a person can see under varying degrees of lighting and contrast, which again is distinct from measuring visual acuity on the Snellen chart. Thus, visual acuity is the precise focus of what the Snellen chart measures.