The instrument used to measure visual acuity is the Snellen chart?

The instrument used to measure visual acuity is the Snellen chart?

• A. Snellen chart (SC)
• B. Refraction test
• C. Perimetry
• D. Ophthalmoscopy

Answer: (A)

Measuring how clearly someone can see details at a distance is tested with the Snellen chart. It uses rows of letters that decrease in size at a fixed viewing distance, and the smallest line a person can correctly identify determines their acuity, usually expressed as a ratio like 20/20 (or 6/6). The top number is the test distance, and the bottom number is the distance at which a person with normal vision could read that same line. This directly gauges visual acuity, making the Snellen chart the standard instrument for this purpose. A refraction test shows how light is focused by the eye and helps determine corrective lenses, but it isn’t measuring acuity by itself. Perimetry checks the extent of the visual field, not the sharpness of central vision. Ophthalmoscopy examines internal structures of the eye, such as the retina and optic nerve, rather than how clearly details are seen at a distance. So, the instrument used to measure visual acuity is the Snellen chart.

Measuring how clearly someone can see details at a distance is tested with the Snellen chart. It uses rows of letters that decrease in size at a fixed viewing distance, and the smallest line a person can correctly identify determines their acuity, usually expressed as a ratio like 20/20 (or 6/6). The top number is the test distance, and the bottom number is the distance at which a person with normal vision could read that same line. This directly gauges visual acuity, making the Snellen chart the standard instrument for this purpose.

A refraction test shows how light is focused by the eye and helps determine corrective lenses, but it isn’t measuring acuity by itself. Perimetry checks the extent of the visual field, not the sharpness of central vision. Ophthalmoscopy examines internal structures of the eye, such as the retina and optic nerve, rather than how clearly details are seen at a distance.

So, the instrument used to measure visual acuity is the Snellen chart.