In a standard eye exam, what is tested to determine visual acuity?

Refraction is the process used during a standard eye exam to determine visual acuity. This testing assesses how well a person can see at various distances and identifies any refractive errors, such as myopia (nearsightedness), hyperopia (farsightedness), and astigmatism. By using a phoropter or a trial frame with different lenses, the eye care professional can measure the smallest letters a patient can read on an eye chart, which directly reflects their visual acuity level.

While other options like color vision, visual field, and visual perception tests are components of a comprehensive eye examination, they do not specifically measure visual acuity. Color vision tests evaluate the ability to distinguish colors, the visual field assessment determines peripheral vision and the extent of the visual field, and visual perception tests gauge how the brain interprets visual information. These aspects are important for overall eye health and function but are separate from the primary measurement of clarity and sharpness of vision that refraction provides.