Question

this chart is used to test what?

a. color blindness
b. visual acuity
c. direction of sound
d. astigmatism

Explanation:

Identify the visual chart

The image displays a circular chart with radiating lines numbered like a clock face from 1 to 12. This specific layout is known as an astigmatic dial or clock dial chart.

Determine the clinical purpose

An astigmatic dial chart is used during eye examinations to detect and estimate the axis of astigmatism. Astigmatism is a refractive error caused by an irregularly shaped cornea or lens, making lines in certain orientations appear sharper or blurrier than others.

Evaluate the given options

• a. color blindness: Tested using Ishihara plates, not radiating lines.
• b. visual acuity: Tested using a Snellen chart (letters of decreasing size).
• c. direction of sound: An auditory test, unrelated to visual charts.
• d. astigmatism: Directly diagnosed using this clock dial chart.

Answer:

• a. color blindness
• b. visual acuity
• c. direction of sound
• d. astigmatism (Correct answer)