title: [The Freiburg Vision Test. Automated determination of visual acuity].
abstract: The Freiburg Visual Acuity Test is an automatic computerized procedure for self-administered measurement of visual acuity. Landolt-Cs are presented on a monitor in one of eight orientations. The subject presses one of eight buttons, which are spatially arranged according to the eight possible positions of the Landolt-C's gap. To estimate the acuity threshold, a best-PEST procedure is employed, assuming a psychometric function with a constant slope on a logarithmic acuity scale. The discreetness artifacts in computer monitors limit the presentation of small stimuli. By anti-aliasing (smoothing of contours by gray-shading), the spatial resolution was improved by a factor of four, such that the shape of Landolt-Cs with oblique gaps is adequate and visual acuities from 0.06 up to 3.6 can be tested at a distance of 5 m.
authors.affiliation: Universitäts-Augenklinik Freiburg i. Br.
authors.forename: M
authors.initials: M
authors.lastname: Bach
mesh_terms: D016477:Artifacts; D006801:Humans; D009949:Orientation; D010364:Pattern Recognition, Visual; D010469:Perceptual Distortion; D011597:Psychomotor Performance; D012684:Sensory Thresholds; D012815:Signal Processing, Computer-Assisted / Q000295:instrumentation*; D014787:Vision Tests / Q000295:instrumentation*; D014792:Visual Acuity
vernacular_title: Der Freiburger Visustest. Automatisierte Sehschärfebestimmung.