Which visual test is primarily used to measure far vision?

The Snellen chart is the primary tool used to measure far vision. It consists of letters arranged in rows, with each row featuring increasingly smaller letters. Patients stand at a predetermined distance, typically 20 feet, and read the letters on the chart. The results are used to assess visual acuity, which indicates how well a person can see at a distance.

By determining the smallest line of letters that can be accurately read, the Snellen chart provides a standardized way to quantify visual capability for distance vision. This makes it a fundamental component of eye examinations focused on assessing how well one can see far away, which is crucial for activities such as driving, reading signs, and recognizing faces from a distance.

The other visual tests mentioned have different purposes: the Cover test is used to evaluate binocular vision and the presence of strabismus, the Jaeger test assesses near vision, and the Contrast sensitivity test measures the ability to distinguish objects from their background based on different levels of contrast, not specifically distance vision.