Introducing " Freiburg Test" as a New and Accessible Psychophysical Method to Evaluate Contrast Sensitivity

Contrast threshold is the minimum amount of contrast required to detect a target in the field and its inverse is called contrast sensitivity. Contrast sensitivity is a complementary test of visual acuity in assessment of visual performance and applied as a potentially useful tool in the early detection of the diseases of visual system. Nowadays, there are several methods for measuring the contrast sensitivity that among them psychophysical tests are the most common. These tests measure contrast sensitivity using a specific and often limited number of spatial frequencies, a constant distance and with a specific optotype, while there is not these limitations in Freiburg test. In Freiburg test, there are various optotypes and in further directions with a variety of different levels of spatial frequency so that running the test is possible in different distances of far, near and intermediate distances. Of the most important characteristics that distinguish Freiburg contrast sensitivity test from other tests are its high sensitivity, reliability and repeatability as well as other qualities such as being standard, new, accessible and affordable. The measurements performed by Freiburg test include several important parameters such as visual acuity and contrast sensitivity.