Subjects and Methods: Twenty-four adult examinees with a visual acuity of ≥ 0,2 were included in the explorative study. The visual acuity of one eye was measured monocularly, randomized with regard to the leading/non-leading eye. The subjects passed every visual acuity test twice in a randomized sequence of the visual acuity tests, which is maintained by a pre-specified randomization list, making use of forced choice.