What instrument is typically used for assessing visual acuity?

The visual acuity chart is the standard instrument used for assessing visual acuity, which measures a person's ability to see details at a specified distance. Typically, this chart consists of letters, symbols, or pictures that are arranged in a decreasing size to test various levels of acuity. The Snellen chart, one of the most widely recognized types of visual acuity charts, helps determine how well a person can read letters at a distance of 20 feet, providing a standardized way to express visual clarity.

In contrast, a retinoscope is primarily used to determine refractive errors by projecting light into the eye and observing the reflection off the retina. The perimeter is a device used to map the visual field, assessing peripheral vision rather than central visual acuity. An ophthalmoscope is utilized to examine the interior structures of the eye, such as the retina and optic nerve, rather than measuring visual clarity directly. These instruments serve different functions in eye care but do not provide a measure of visual acuity like a visual acuity chart does.