A) For the investigation of Visual acuity, inter-test agreement and the test-retest reliability were used three different visual acuity tests: ETDRS charts, Landoltring chart and Freiburg Visual Acuity Test (FrACt). The examinees passed each visual acuity test twice but the sequence of the visual acuity tests were randomize and so different for each examinee. The examinees were 24 adult Aalen university students (except students of ophthalmic optics in terms 2 - 7) with a minimal distant visual acuity without or with correction of 0.2. Another inclusion criteria was a maximum myopia of sph -2,00 dpt, a maximum hyperopia of sph +5,50 dpt and a maximum astigmatism of cyl 2,50 dpt. The Landolt C was projected in eight-orientations. For the FrACT Test we used two different devices for response input: a modified keypad with Landoltring symbols (FrACTk) and a haptic Landolt device with an adjustable Landoltring (FrACTh). The primary objective was the comparison between FrACTk and FrACTh. The secondary Objective contains the comparison between all visual acuity tests.