Bach M
Universitäts-Augenklinik Freiburg i. Br.
Ophthalmologe. 1995 Apr;92(2):174-8.
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.
弗莱堡视力测试是一种用于自我测量视力的自动计算机化程序。兰多尔特环（Landolt-C）以八种方向之一呈现在显示器上。受试者按下八个按钮中的一个，这些按钮根据兰多尔特环缺口的八个可能位置在空间上排列。为了估计视力阈值，采用了最佳PEST程序，假设在对数视力尺度上具有恒定斜率的心理测量函数。计算机显示器中的离散伪像限制了小刺激的呈现。通过抗锯齿（通过灰度阴影平滑轮廓），空间分辨率提高了四倍，使得具有倾斜缺口的兰多尔特环的形状足够，并且可以在5米的距离测试从0.06到3.6的视力。
