To identify and view objects and to distinguish them from their surroundings, the eye uses the light emitted from the edges of each object. The basis of the contrast sensitivity test is to check the amount of eye power to detect an object on a field. The closer the color and shape of the target object and the field, the more difficult it is to distinguish between them. Different objects on different fields are used in this test. Contrast Sensitivity decline is seen in many eye diseases and disorders such as corneal diseases, cataract and retinal degenerative diseases.
Contrast Sensitivity Test
Retinal and optic nerve diseases and corneal opacity of the eye (cataract) can reduce the contrast perception (bright shade), which in many cases occurs much earlier than visual acuity impairment. Using the relevant standard eye charts is the best way to examine it. On these charts some circles with parallel white lines inside are drawn in a gray background. From one circle to the next, the direction of these white lines changes and the contrast of the lines is reduced as well. Therefore, when the contrast of the lines is decreased a patient with an impairment of contrast sensitivity cannot understand and express the direction of the white lines, so the ability of the patient’s contrast perception can be determined with number. Standard ambient lighting is essential in this test.