Our eyes usethe light radiated from the edges of each object to detect and see things and also identify them from their environment. The contrast sensitivity test is based on the ability of the eye to distinguish an object from its background. The more closerthe color and shape of the target object and its background are to each other, the more difficult it is to distinguish them from each other. In this test, different things on different surfaces are used. Cs loss occurs in many eye diseases such as corneal disease, cataracts and retinal degenerative diseases.