[The Freiburg Vision Test. Automated determination of visual acuity]

Ophthalmologe. 1995 Apr;92(2):174-8.
[Article in German]


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.

Publication types

  • English Abstract

MeSH terms

  • Artifacts
  • Humans
  • Orientation
  • Pattern Recognition, Visual
  • Perceptual Distortion
  • Psychomotor Performance
  • Sensory Thresholds
  • Signal Processing, Computer-Assisted / instrumentation*
  • Vision Tests / instrumentation*
  • Visual Acuity*